Peer Reviewed Study: Grid Connect Solar Helps Environment But Batteries Harm It

academic in ivory tower

A paper published in ‘Nature’ has agreed with Ronald’s back of an envelope conclusions from last year: at the moment, most grid connected storage harms the environment.

Almost a year ago I wrote an article about how on-grid home battery storage does not help the environment but instead harms it by increasing greenhouse gas emissions and other types of pollution. I am raising this topic again, hoisting it above my head, and waving it around, because a scientific paper published in the journal Nature vindicates my position.

On-Grid Home Batteries Don’t Reduce Emissions Or Save Money

Right now I want to be like the glass they put in fiber optic cables — perfectly clear.

Under the right circumstances batteries can reduce emissions. For example:

  • Batteries used with export limited solar systems.
  • Batteries in electric vehicles if the power they’re charged with isn’t too filthy.
  • Batteries used off-grid.
  • Batteries that store a sufficient amount of renewable energy that otherwise would go to waste.

But at this current time, on-grid home batteries only increase and do not decrease greenhouse gas emissions. This could definitely change in the future. But we’re definitely not in that future yet.

On-grid home batteries don’t save money. There is no battery system available that is a worthwhile investment for any home with remotely normal electricity use. I have gone into the economics of why this is the case in the past and I will no doubt go into it again soon enough.

This is not me saying don’t buy home battery storage if that’s what you want. This is me saying go into it with your eyes open.

Let me be clear that I am not “anti-battery” as many people are accusing me. I am simply “pro truth”.

Now watch me pull a couple of scientists out of my butt to back me up on this.

The Scientific Paper

The paper published in Nature is called “The impacts of storing solar energy in the home to reduce the reliance on the utility” and, for the moment at least, you can read it here for free. But before long you may have to pay $65 . This is because while the internet can give us infinite free pornography, doing the same for useful scientific knowledge is apparently beyond its ability.

How the internet was created

Engineers had to make some tough choices back in the 50s. This is why we currently don’t have flying cars.

Fortunately, scientist dude prime, the one whose name appears first on the paper, Robert L. Fares, has written an article in Scientific American summarizing its conclusions. This is handy for those who don’t want to wade through all the details in the paper.

Why Home Battery Storage Increases Emissions

In his article, Bob Fares explains why home battery storage is currently bad for the environment and I am going to quote a whole paragraph because it’s easier than writing myself:

“Our study found that storage provides a benefit in the form of reduced power flows in the distribution grid, which can lead to utility infrastructure cost savings. However, because some energy is lost every time a battery system charges and discharges, storing solar energy for later use in the home actually increases energy consumption versus just sending it directly to the grid. And with todays fossil-fuel powered electric grid, the increase in energy consumption also leads to an increase in overall emissions.”

So if your rooftop solar system sends surplus electricity directly into the grid it will cut fossil fuel emissions, but because there are always energy losses when using batteries, total grid electricity generation will be higher if a home uses batteries and so emissions will also be higher.

Far out Fares goes on to say:

“In other words, if a household with solar panels wants to reduce its emissions footprint, adding energy storage is a bad idea.”

What The Study Looked At

The two authors of the paper, Bobby Fares and Michael E. Webber, looked at the 2014 energy consumption and production of 99 homes with rooftop solar in Austin, Texas. (Austin is the capital of Texas and presumably named after the Six Million Dollar Man in honor of him defeating bigfoot.)

They then modeled1 what would happen if the solar households installed a 7 kilowatt-hour battery that provided 3.3 kilowatts of power and had 85% round trip efficiency. In other words, something like the original Tesla Powerwall, but with greater storage capacity.

They considered two different ways the batteries could be used:

  1. To lower household grid electricity use.
  2. To lower the peak power the household draws from the grid at any one time.

In the first situation batteries were used at around 88% capacity. This meant they averaged 0.88 cycles a day. In the second condition they were used at approximately 150% of capacity and so were cycled an average of 1.5 times a day.

Australian households normally only use their batteries to lower grid electricity use, which is the first condition. While it is definitely possible to average 0.88 cycles a day with a 7 kilowatt-hour battery, most households will average less. The larger the battery, the lower the likely daily cycle average.

Australian homes don’t normally use batteries to reduce the maximum amount of power drawn from the grid, as residential demand tariffs that encourage this are rare2, but it is something businesses can be interested in.

Under both conditions batteries were found to increase emissions, with the second condition increasing emissions more because they were used at a higher capacity.

In The Texas Grid Batteries Increase Emissions

Because energy is always lost when charging and discharging batteries, homes with them use more energy than those without. The difference is made up by increased grid generation, and at the moment, this will result in increased emissions pretty much everywhere in the world.

They looked at the effect of batteries in the Texas grid which looks like this:

Texas electricity by source

That is 44% natural gas, 29% coal, 6% nuclear, and 21% renewables — which is largely wind.

The authors looked at 2014 generation, which was similar, but back then renewables only provided about 15% of electricity3.

Unfortunately, Australia’s grid is much more coal dependent and so much more emission intensive. This means battery storage will result in more greenhouse gas emissions and other forms of pollution here. This is the case even in South Australia with its high penetration of wind power and rooftop solar, as almost all surplus renewable energy is exported to coal heavy Victoria.

Round Trip Efficiency

The study assumed the batteries had a round trip efficiency of 85%. This means if 1 kilowatt-hour was put into the battery, only 0.85 kilowatt-hours could be got out. It is definitely possible to have a higher round trip efficiency than this. For example, Tesla claims the round trip efficiency of their Powerwall 2 is 89%, but I suspect under real world conditions it will be slightly less. With an efficient battery and inverter it should be possible for batteries to have a round trip efficiency of over 93%, but as long as it is less than 100% batteries are likely to increase emissions and 100% efficiency is impossible. The study found that, in Texas, round trip efficiency had to be almost 100% before CO2 emissions were reduced.

So while it is possible to reduce the emissions resulting from using home battery storage use with higher efficiency, in practice it would be difficult to reduce emissions by more than half the amount that would result from the 85% efficiency assumed by the study.

Battery Harm Is Small Compared To Solar Benefit

The good news is the harm caused by batteries is only small compared to the benefit provided by rooftop solar. So if you have installed rooftop solar and batteries you are not a total monster and overall the planet is coming out ahead. Rather than kicking the environment in the nuts, you’re more giving it a nice hug followed by a slap.

In his Scientific American article, Robbo Fares compares the benefit of solar with the harm caused by batteries in the following graph:

Solar benefit vs battery harm

As you can see, the third column, which is the “target zero” condition where home batteries were used as they normally are in Australia, resulted in a very small increase in electricity consumption compared to the blue-green rectangle, which is was the average decrease in grid electricity generation resulting from rooftop solar. (Judging by the amount of electricity produced, the average solar system size in the study was roughly 6 kilowatts.)

So if you have batteries you don’t need to feel terribly guilty about the harm they are causing the environment, provided you didn’t forget to install a solar system. But if you installed batteries to help the environment and reduce emissions, then you should feel a bit dopey, because you have managed to do the exact opposite.

Expanding Rooftop Solar And Energy Efficiency Are Better Options

As the graph above shows, rooftop solar provides a major benefit while batteries cause relatively minor, but real, harm. So if your goal is to be green you are far better off expanding your rooftop solar capacity than getting batteries. Improving your home’s energy efficiency is another worthwhile option.

Another possibility is putting the money you would have spent on batteries towards getting an electric car. An electric vehicle will reduce emissions now, provided it isn’t charged with electricity that is too filthy, while also being able to support greater renewable generation in the future by charging with clean renewable electricity that would otherwise go to waste4.

Batteries Don’t Save Americans Money

The study mentions that batteries don’t save American households money. Because electricity prices and feed-in tariffs can be dramatically different in Americaland, this isn’t very relevant for us. But I’ll say it once more, without feeling — since I’ve said it so many times I now just repeat it robotically — batteries don’t save money. Yet.

Emissions From Manufacture

When I wrote about the environmental effects of batteries last year I mentioned emissions from their manufacture. Bobbo and Mike don’t go into this in their paper. I think there are two reasons why they didn’t, and they are:

  1. Emissions from battery manufacture are only a small portion of total emissions from their use.
  2. There is no good information available on how much emissions result from manufacturing modern batteries.

In my article I had to use outdated information from a 2013 study because that was all there was available. But I did make a point of stating that it was outdated and I was certain emissions from manufacture were actually less.

A few months ago you may have heard of a Swedish study that said emissions from battery manufacture were very high. But it definitely did not give any useful new information5. I know this because I am very familiar with the figures used. They are exactly the same ones from the outdated 2013 study. No new research was done. It simply recycled old information. I hope the Swedish Transport Administration and Energy Agency didn’t pay much for it, because I could have pointed them towards the original study for free.

While I don’t know how much emissions result from battery manufacture, we can be certain they are less than what they were because:

  1. Energy density has increased, reducing the amount of material required per kilowatt-hour of storage.
  2. The renewable portion of energy used to make batteries has increased.
  3. They are a hell of a lot cheaper, which is a good indicator that both material and energy costs of production have decreased.

So if you are looking for home batteries that cause the least environmental harm, don’t worry about emissions from manufacture, instead get a system with highest possible overall round trip efficiency.

Batteries Can Reduce Transmission Infrastructure Costs

The paper makes it clear home batteries can reduce the need to build new transmission infrastructure and so reduce grid transmission costs. But until Australians are offered worthwhile ways to save money on their electricity bills by reducing power use when the grid is under stress, this won’t enable batteries to save money.

There are people working on this problem in various ways, but so far no one has provided me with evidence they can make battery systems pay for themselves at the moment.

Batteries May Provide Environmental Benefit In The Future

Robert L. Fares and Michael E. Webber’s paper makes the point that:

“…home energy storage would not automatically reduce emissions or energy consumption unless it directly enables renewable energy.”

The words “directly enables” means the battery storage either prevents renewable energy going to waste or that renewable generating capacity wouldn’t be built without it.

The study also mentions how little it costs to add new renewable capacity to the grid and I am going to quote their paper quoting another paper6 on the topic:

“A study on the impacts of rooftop photovoltaic panels in California found that even at 100% penetration (measured as the ratio between nameplate capacity and peak system demand), the utility Pacific Gas and Electric (PG&E) could maintain adequate voltage levels in its system by increasing the number of transformer tap changing operations at a cost of US$442,000 annually–or 0.007% of its US$6 billion annual operation and maintenance budget.”7

This is an important point because the Australian Energy Market Operator (AEMO) says South Australia could, at times, meet all electricity demand with power generated by rooftop solar alone by 2023.

If renewable generating capacity continues to rapidly expand in South Australia it may not be long before home battery storage will benefit the environment. But if new transmission capacity is built to coal heavy Victoria or NSW, that day may be delayed.

Also, if enough new storage capacity ends up in other places other than stationary storage in homes, such as electric vehicles, utility scale battery storage, or new pumped hydroelectric schemes, it is possible home batteries may never end up providing an environmental benefit — although they would stop being an environmental minus. But we’ll have to wait to see what happens.

Currently in Australia, rooftop solar electricity sent into the grid directly reduces fossil fuel generation, while almost no renewable energy goes to waste due to a lack of storage. This is true even in South Australia with its high penetration of wind power and rooftop solar. While I am optimistic about the speed Australia’s coal capacity will be shut down, we are definitely not at the point where home batteries will help the environment. So if your goal in getting batteries is to be green, hold off for now. Not only will you prevent yourself from doing the opposite and increasing emissions, you’ll also save yourself money.

Robert L. Fares and Michael E. Webber in the US agree with me and when have Americans ever been wrong about anything?

A note from Finn Peacock, founder of SolarQuotes® :

This blog post was written by our illustrious blogger, Ronald. I have added this note because I know the subject matter will upset some readers.

Over the years, there have been a number of people who have contacted us and accused us of being anti-batteries. A large battery sales company has even threatened to ‘destroy’ us.

I want to make it very clear that at SolarQuotes® we are not anti-battery. The suggestion is ridiculous. What we are is pro-truth.

A peer-reviewed study in a respected scientific journal is about as objective as it gets and we decided to report on it.

A year or so ago, Ronald sat down and thought about the environmental effects of home battery storage and came to the same conclusion using common sense and some basic arithmetic.

So, were not saying ‘don’t buy batteries’. We just want people to go into it with their eyes open. The objective facts are, for most people, buying batteries will not save money, and will slightly harm the environment.The amount of environmental harm caused by batteries is only minor compared to buying a petrol guzzling car. But if your goal is to protect the planet, then buying batteries is the opposite of that.

This could change in the future. When Australia produces enough renewable energy, batteries can help the environment. I hope this day comes soon, because, as you can see, I am very green.

But we are not there yet. Until we are, what you can do to protect the environment is expand your rooftop solar capacity, invest in home energy efficiency or get an electric car. Or even better an electric bike.

SolarQuotes is not anti-battery. We have no financial interest in dissuading people from buying batteries. The opposite is true. The more people there are buying batteries the more people will be seeking quotes for them. Because we offer quotes for batteries this means more people will come to SolarQuotes and make SolarQuotes more successful.

It is absolutely in SolarQuotes’ interest to encourage people to buy batteries. But were not going to lie and claim they provide an environmental benefit when they don’t or ignore the environmental harm their use causes.

What this blog is about is attempting to give consumers impartial, objective analysis about solar, batteries, and related topics.

This post is an example of that. I think its very objective. And quite funny. It is, as I said, based on a peer-reviewed study. We trust the scientific process. By all means, engage with us, leave comments, email. But do read the whole blog post first and look at the caveats Ronald’s put in there before replying.

If you disagree with the conclusions, feel free to attempt to convince us that we are wrong, but you will need to make a good argument. 


  1. Modelling is like pretending, except that if you want to claim Batman could fight Superman and not end up as bat paste, you have to be able to back it up with math.
  2. And stupid.
  3. Wind power has really taken off in Texas and solar power is also expanding.
  4. Electric vehicles can also send electricity into the grid when demand and prices are high, but not all-electric car manufacturers are on board with this.
  5. The Popular Mechanics article shows a couple of problems with the Swedish study without even going into the fact the information used is horribly outdated.
  6. If this results in a quote apocalypse as the quotiverse collapses in on itself — my bad.
  7. They go on to say, “These findings align with previous findings on the impact of high photovoltaic penetration in distribution circuits in California. Furthermore, a number of studies have shown that upgrading conductors, upgrading the transformer, or incorporating ‘smart’ phototvoltaic inverter control could be used in lieu of storage to maintain adequate system voltage.”
About Ronald Brakels

Joining SolarQuotes in 2015, Ronald has a knack for reading those tediously long documents put out by solar manufacturers and translating their contents into something consumers might find interesting. Master of heavily researched deep-dive blog posts, his relentless consumer advocacy has ruffled more than a few manufacturer's feathers over the years. Read Ronald's full bio.


  1. Hum… maybe you do not know how battery storage works with a PV system nor do the authors you quote as well.

    ” However, because some energy is lost every time a battery system charges and discharges, storing solar energy for later use in the home actually increases energy consumption versus just sending it directly to the grid. ”

    When a battery is used and charged during the DAYTIME to store EXCESS solar energy INTO the battery then you use that excess energy during the NIGHT the grid does NOT use any more energy, it USES less. This is why the utilities hate solar and double hate batteries and PV. This guy has his head up his ass. Plain and simple. Yes it does increase your energy usage from SOLAR and NOT from the gird. And it is cycled by solar not by the grid. Yes some energy is lost because no battery is 100% efficient, but that is not grid energy lost it is solar energy lost. Gezzzz…

    JD BeUtilityFree USA

    • Ronald Brakels says

      John, if my solar system generates 10 units of electricity energy and I send them into the grid, fossil fuel generation will be reduced by 10 units. If I instead use those 10 units of solar electricity to charge a battery system with 90% round trip efficiency I will only be able to get 9 units out for my own consumption in the evening. Therefore my electricity consumption at night is only reduced by 9 units which will only reduce fossil fuel generation by 9 units.

      So in this example, without using batteries fossil fuel generation is reduced by 10 units and with batteries fossil fuel generation is reduced by 9 units.

    • John,
      The excess solar energy could be used direclty during the day. If Solar is to be considered as being part of the energy supply, waste is waste.
      During the evening peaks (and other times too) the battery’s output has a negative effect on the marginal emissions of the generators, lowering their efficiency, and raising ghg. The benefits of solar ( the blue column) come from
      reduced grid consumption, not offsetting ghg.

    • I think we can see who has his head up his ass!

  2. Small flaw in the analysis. Peak demand occurs between 4-8pm, which is when you will be generating little solar power. So the grid has to supply greater power during this period, meaning an increase in greenhouse gases (assuming coal/gas). Battery storage enables the use of the “shoulder” produced solar power during a peak time, reducing the need for extra power generation during the peak time. With sufficient battery storage the peak would be reduced, meaning less power would need to be generated at peak times = less greenhouse emissions

    • Ronald Brakels says

      Australia currently produces most of its electricity from fossil fuels, so each kilowatt-hour of solar electricity sent into the grid during the day reduces fossil fuel generation by around 1 kilowatt-hour. If I store one kilowatt-hour of solar electricity for use in the evening in a battery system with 90% round trip efficiency it will only reduce fossil fuel generation by around 0.9 kilowatt-hours. So there is greater reduction in fossil fuel use and emissions without using batteries.

      • You are correct if FF generation mimics demand, but it doesn’t. Base load coal, which is still the predominant energy production in Australia (75%ish), is not able to respond to peak/troughs like other forms, and unfortunately this continues to run to meet a certain level of demand. So increasing amount of solar generation in the middle of the day does not reduce the amount of emissions as these base load generators continue to run. So you do not get a 1:1 reduction in emissions by putting out more solar in the middle of the day. It wouldn’t even get close to the battery round trip efficiency. So theoretically your argument may stand assuming “perfect” demand driven generation, practically it absolutely doesn’t translate.

        • Ronald Brakels says

          Realist, under normal circumstances Australian fossil fuel generators don’t supply electricity to the grid that isn’t required. If they do, electricity prices go negative. This means they not only have to pay for the cost of the fuel they are burning, but they also have to pay for every kilowatt-hour they send into the grid. Since companies that own generators like to make money and dislike losing it, they very rarely supply more power than is needed.

          If you go to the Australian Energy Market Operator site:

          You will also be able to see that daytime demand in every state is currently consistently above baseload demand in the early hours of the morning.

          • They still burn fuel irrespective of whether they delivery power to the grid. They don’t just stop burning when there is a dip in demand. My point stands that your 1:1 reduction isn’t correct. You are taking into account battery conversion losses whilst assuming 100% offset on the other side. Doesn’t stack up.

          • Ronald Brakels says

            So at four o’clock this morning when demand was about at its lowest, the wholesale price of electricity was around 7 cents through the National Electricity Market. You are saying at this time coal power stations were generating excess power they could have sold to the grid, but instead they decided not to. Interesting idea, but that’s not how it works.

          • Ronald, power stations always produce excess power that they don’t sell into the grid (unless demand outstrips supply, but that’s a bigger problem). The boilers in coal power stations keep burning coal to maintain steam pressures so they can ramp up the turbines as demand changes, but they usually have an excess of generated power. They have to, so they can meet expected peaks. Are you now trying to say that power stations produce exactly what the market wants all the time??

          • Ronald Brakels says

            Hello Realist.

            A lot of effort is put into ensuring grid electricity remains within set ranges of frequency and voltage. Under normal circumstances the amount of electrical energy required to remain within these ranges is supplied to the grid. This is done over a period of minutes by generators that have contracted to provide ancillary services and also by solar inverters during the day. Over the slightly longer term this is done through the electricity market which pays generators to meet demand and, at times, penalizes an oversupply of electricity.

            So, via these two mechanisms, the amount of electricity that is required by the gird is normally supplied.

            Generally, under 30 gigawatts of coal capacity is operating at any one time in Australia. As Australia’s aging coal power stations can typically operate from around 60% to 100% of capacity, this means coal generation is normally quite capable of supplying less than baseload demand, which was around 20 gigawatts in the National Electricity Market early this morning.

          • Csaba Urbaniczky says

            “Are you now trying to say that power stations produce exactly what the market wants all the time??”

            YES YES YES. That is how electricity works

  3. I’m sorry I just don’t understand how you can conclude batteries will increase fossil fuel grid usage. If I install batteries (which have a fixed co2 usage during manufacturing), even though they do introduce losses during charging and discharging – it’s simply losing solar energy.

    I need to charge it longer with solar than a 100% efficient battery, and when I discharge it, it will output less power than a 100% efficient battery. How this would increase fossil fuel usage is not clear.

    Perhaps you’re trying to say it will mean less solar is going into the grid for other people to use?

    Fossil power plants are running overnight way beyond required capacity because they can’t be throttled down (especially coal) anyway. But using your own solar at night (through a lossy battery) means you’re not using that capacity – and the more this happens, the quicker the fossil fuel generator will be shut down.

    Until then, this is the perfect case where electric cars running on 100% fossil fuels will not increase emissions if charged overnight because these power plants are online anyway producing power that doesn’t get used.

    If we forever use fossil power at night it will never be made redundant.

    • Ronald Brakels says

      Hello Peter.

      There is more electrical energy available in total when people send their surplus solar electricity directly into the grid than if they use it to charge batteries. The losses from using batteries will, currently in Australia, be made up for by fossil fuel generation.

      So if my solar system sends 10 kilowatt-hours of electricity directly into the grid fossil fuel generation will be reduced by around 10 kilowatt-hours. But if I instead use a battery system with 90% round trip efficiency to store those 10 kilowatt-hours it will only reduce my electricity consumption by 9 kilowatt-hours in the evening and so only reduce grid fossil fuel generation by 9 kilowatt-hours, as I will make up for the lost kilowatt-hour by using grid electricity.

      In the future we may produce so much surplus solar electricity that fossil fuel generation is eliminated during the day. In that case, storing surplus solar electricity for use in the evening could reduce fossil fuel generation then, but unfortunately we are currently far from that point.

      • Peter Nemere says

        The issue for me is reducing fossil fuel at night where in Australia that’s pretty much our only power source besides some small hydro… Think of it this way, a battery can take a whole house off the grid day AND night.

        In our case we have 3.3kw of panels making currently 18kwh/day (Qld). We use about 11kwh a day, of that about 6 is at night. A powerwall 2 is way too big for us, though would have a very long life with only <= 50% cycling daily…

        Like many we export heaps during the day but I haven't heard of any fossil plants closing in Qld and because it's heaps of coal power here they keep things hot to cater for night when nobody has solar boosting into the grid.

        So if all houses that have solar also have batteries the night time energy usage would drop significantly and there would definitely be plant closures. This should be the ultimate goal.

        I've got space for 2 more 330w panels on my roof, and because it's micro inverters they'll install easily, when I get the powerwall they will cover any losses…

        On the other hand lately I've seen more talk about "using the hot water tank as a battery". I've found if I only run the hot water during the day I can maximize self consumption and reduce night time power usage by 2kwh… However because the water cools down more by morning, it uses about 50% more solar to reheat it. By your arguments that's terrible and producing more fossil fuels because that solar is not feeding into the grid…

        With a powerwall I won't be doing the above with hot water as I'll want to use the least amount of power overall as it's all solar. Until then I want to use the least power overnight because that's fossil while during to day I have solar…

        • Aaron Murphy says

          Spot on Peter

        • What sort of hot water system? I have an insulated tank beside the house with a (water) solar system on the roof. There is a booster element that runs off a grid operated switch for cheaper off peak power at night. 350litres, does not cool down overnight and I have turned the circuit breaker off (for the off peak element) and with the sunlight on the mid north coast, haven’t paid for heating power for 3-4 months.
          So much better to have solar hot water.

      • Ronald, your premise would be true if you actually needed to use that extra kwr and it came from the grid.
        I have a battery and I can tell you that my bill is negative. Ie. Ergon pays me each billing cycle, even with their criminally high meter charge/day.
        So you can’t say that my battery is causing more greenhouse emissions than if I didn’t have it.

        • I have 23 panels and have been paid for my power for quite some months and have built up a large credit (12.8c /kWh)
          Have to agree with Ronald, no need for batteries. Worked out over 10 years to be a cost 41c/kWh, more than the cost from the grid.

    • AndrewATA says

      Coal-fired power plants can be throttled down. And since the grid is interconnected between states, the one that reduces is output might be a long way from you are.

  4. Storm in a teacup. It should hardly warrant an academic study to conclude that because battery efficiency is less than 100% some of power stored rather than exported will lead to more power having to be generated, to cover that efficiency loss. The impact on the environment will be determined by the “dirtiness” of the generating capacity that is turned on “at the margin” to meet the demand. What will that be for Australia? I presume that would normally be gas, given the coal stations are used for baseload, and solar/wind are intermittent – they are there when they are there, but they can’t be turned on at will. Where’s the controversy in that?

    • Ronald Brakels says

      Hello. At the moment, solar electricity sent into the grid during the day mostly reduces coal generation. Electricity from batteries used in the evening is more likely to displace gas generation, but because Australia is so coal dependent and uses a considerably amount of hydroelectric power to meet peak demand, battery energy used in the evening will generally still displace a significant amount of coal generation.

      The controversy is that quite a few people are unaware that battery systems don’t yet help cut emissions and in practice do the opposite.

      • Aaron Murphy says

        I think you are mistaken about the controversy.

        If you have FF generator x, which cannot be throttled very fast to meet demand like coal, which is why peaking gas exists in the first place, then during the day, when solar is generating, there is an oversupply of FF generation.
        This is supply doesn’t make it to the grid however because the generator controls how much is sent to the grid. Emissions from this generator do not decrease however. This works much like a oversized solar system. Yes, the panels have instantaneous capacity to generate more, but it is limited by the output of the inverter. In the FF generators case, this is an artificial limitation as to not overvolt the grid. However as the sun goes down, all this capacity is required, so in combination with the gas peaking plants, the artificial limitation is taken away and the output the grid sees increases.
        Increasing solar output to the grid is not going to reduce emissions because of the simple fact FF generation is not quick enough to respond. HOWEVER, with battery storage, that evening peak is pushed further back, and back until there is no evening peak and the FF generator runs permanently at a lower capacity, reducing emissions and eventually shutting down.

        This is all not to mention the other benefits batteries storage gives you, such as blackout protection.

        • Ronald Brakels says

          Aaron, I get the impression you think Australia’s coal power stations are unable to vary their output. If you go to this site and write down coal generation at several periods through the day:

          You can see coal generation varying in response to demand.

          UPDATE: For example, yesterday Queensland coal generation was 5.62 gigawatts at around 12:30 in the afternoon when demand was low and around 5:00 was 6.7 gigawatts as a result of increased demand.

          • And a corresponding reduction in emission with this reduction in output. It is quite common for coal generators to be load following.

          • Aaron Murphy says

            Unfortunately it seems as though you have completely missed my point like you did in your post Ronald.

            I did not say coal generators cannot vary their output. As you said, they most certainly can otherwise we would have wild voltage and frequency swings.

            What I did say however, is the output that varies is what the grid sees. Which is why on NEM watch, which I keep an eagle eye on, also shows a change in generator output.

            Like I said in my previous comment, at the generator, the available output (read not actual output that the grid sees) is higher so the generator can respond to energy demand fluctuations in a reasonable time and due to this higher available output, emissions stay higher, regardless of the solar output because of evening demand, demand of clouds cover the sun, demand of a powerline breaks etc.

          • Spot on Aaron

            Output from these FF generators is ALWAYS less than generated capacity – if it were ever to drop below then the power station would effectively stall – not good.

            Considering the FF grid as an infinite storage facility made sense when there was hardly any renewable generation, but now we must see them with their real world problems – reducing demand by virtue of renewable generation is not a 1:1 relationship as clearly explained in this thread. Add to this the additional grid restrictions in Victoria for example which currently prevent solar feed-in for many zone substations, and the environmental benefit equation in favour of residential batteries is the opposite from the papers quoted here. There is clearly a significant greenhouse gas benefit to installing them in most Australian jusrisdictions.

            As for a financial benefit – if you consider the large scale it will be far cheaper to provide storage at the utility scale rather than residential – but that is a matter of politics, not science. If the feed-in tariffs from 10 years ago were still in place the idea of a residential battery would be laughable. There is no way that your own storage battery could compete with the option of feeding into the grid. But as we know electricity producers are not in the business of reducing the amount of electricity they sell, and have to be pushed into accepting renewable feed in. On current metrics it looks like residential batteries could actually become financially viable soon.

            HOWEVER, I don’t think we should aim for a situation where residential storage batteries are financially viable – we should put our energies and $ into making the grid viable as a real storage option – that would be even better for the environment and greenhouse gas problem than buying an electric car!

        • The ‘target zero’ mode, restricts battery charging to solar input, and the output to powering the house. The battery does not output directly to the grid, nor charge from it.

          Over the year, the accumulated energy lost to inefficiency, must be replaced by grid demand. The grid could be a completely stable coal, or completely stable natural gas generation, and ghg would increase when the battery is included, because the battery’s losses are a load, like any other.

          The magnitude of the ghg produced by the battery, depends upon the grid mix. The authors examine many grid mixes. Their conclusion is that batteries add ghg in all of the cases.

          Excess solar sent to the grid, may reduce total ghg (or not), but when a battery is present, the total household ghg increases over solar only.
          For that reason it is a red herring to argue for changing coal levels at night, for example, because relative to solar only, and for all of the examined grid mixes, the battery increases household ghg.

          Solar can definitely reduce grid demand. That benefit to the environment could be used to justify a battery, but no more so than using the same arguement to justify buying wide-screen TV or some other item.
          The study offers
          “The mean increase in annual energy use across the 99 households is 338 kWh when storage operates in the ‘target zero’ mode.
          Add to that, the embodied ghg of battery manufacture, and the disposal problem that will be left to the owner.

      • Caroline Copley says

        There are an awful lot of people who don’t understand the damage that larger scale Hydro Power does to the environment either, not least of which involves:
        – disruption of temperature regimes and thus fish breeding;
        – straightening of streams and thus worse flooding;
        – flooding of sections of upper streams resulting in extermination of frog habitat; and
        – the list goes on and on.

        Use of dams in hydro is absolutely disastrous for the environment, there is much about this in the national Snowy Water Inquiry held some years ago if anyone is interested.

        You can’t call yourself environmental minded and be in favour of large scale hydro.

  5. Wayne Morellini says

    Your site just wiped my post as I was going to post. Forgive the errors I haven’t read this, I’m sick, but know what is happening.

    Check to see if it is unbiased unpromotional science.

    Check to see if they are using historical or current and projected future data. Decades past grid solar might have had advantages, but in the future I don’t think so.

    Next, the grid itself uses a lot of smelted materials and other manufactured materials in infrastructure and maintenance, plus people driving to work to maintain it. The grid also has significant energy losses accross it compared to household storage. It would have to be a bad battery technology not to compete with grid solar, as apart from the losses the grid needs storage too. Centralisation of grid power generation may have some advantages, but should be wiped out between grid and distant household.

    Looking into the future, more efficient and cheaper per unit of performance solar, and much better battery technologies, should favour household solar, as the technologies increase the proportional cost of the grid. Local grd supplementing house solar might be a good option.

    So, there is a liquid chemistry lithium battery that doesn’t wear out supposedly under development, and things like silicon nanowire with projected upto 10x charge capacity and a great amount of recharge cycles.

    It is not about the past figures, but the present and realistically projected future figures if future development.

  6. AndrewATA says

    Thanks for saying this again. We made the same points back in March 2016 in ReNew magazine. Many people have trouble understanding the environmental value of solar exports to the grid. And that charging a battery from excess solar reduces that environmental benefit, outweighing the benefit of reduced night-time imports from the grid.

    Installing a battery does have a long-term, indirect environmental benefit. It helps build the battery industry by experience and economies of scale. As you mention, this will be important later on when renewables make up most of the grid generation.

    • Lawrence Coomber says

      An integrated DC coupled solar PV and battery bank is a perfect and efficient minimised losses recipe for continuous autonomy Off Grid Solutions though.

      Lawrence Coomber

  7. I think I get that batteries charged from an oversized solar array may lower my green house gas emissions because I import less from the grid, but that on a macro basis there is a net increase in emissions (assuming most evening peak demand is coal or gas rather than hydro because of battery inefficiency. Of course this assumes that there is no/little/comparatively less generation and transmission losses than there are battery losses.You don;t seem to consider the possibility that to give 100 units to a house in Sydney?melbourne etc you might have to generate 110 units and that there is substantial heat loss in generation that is also fed by coal.

    Second I find it hard to believe that running solar generated energy from a battery during the early evening peak demand/TOD charge is not cost effective for households otherwise paying full TOD prices in the evening, even after taking into account the cost not only of the battery but of the increased solar array to produce the energy stored for later use.

    I also struggle a little with battteries not being money savers when recharged from lowest cost TOD and used during the morning low solar/high TOD charge period, but can understand this is more likely to be marginal and may be an uneconomic use of the available cycles compared to only cycling say .85 per day rather than say 1.5 per day where the second cycle (ie for the morning before solar supply kicks in) given the extra cycle has to pay for off peak power.

  8. niels faerch says

    Completely unrelated to this article. Sorry..

    But, Ronald, how about doing an article on the cost of electricity in various parts of the world versus Australia. We need to know how we are being ripped off.

    China for example is around 8c/KWh – and that’s after they ship the coal all the way from Queensland. India, I believe is even cheaper.


    • Ronald Brakels says

      Well, in China electricity prices seem cheap because they have a crazy system where normal everyday people pay less for electricity than huge industrial corporations. In Australia, it’s the other way around, as god intended. Let’s all hope and pray the Chinese people stop oppressing their industrial conglomerates soon.

      • Nice one Ronald. I wonder how many people will miss the irony. It’s always struck me as crazy that people who use more energy are charged less for it. Even some residential electricity contacts provide a cheaper price once you go over a certain amount of usage. It simply encouraged people to use more energy. What a wonderful way to reduce carbon emissions!

    • Page 1 of the The Australian, today (09-082017) has a table sourced from “US Energy Information Administration” I had a look on the US-EIA site but could not find the original material (among their public-accessible datasets).

      It’s not clear whether the figures quoted are in US cents or converted to AUD cents, nor whether this is average or peak period price, but a couple of entries are:
      South Australia 47.12 c/KWhr
      NSW 39.10
      EU Average 29.85
      Hungary 17.16

      • Ronald Brakels says

        On my last electricity bill here in South Australia, I was charged 51.6 cents for every kilowatt-hour of grid electricity I used.

  9. Pat Comerford says

    You make a bold assumption that people install storage batteries to contribute to a reduction in carbon emmissions. Where is your basis for this claim.
    I can say with 100% assurance I am installing battery storage in order to give the finger to the big power companies that are holding consumers to ransom.
    I installed my PV system to help cut emissions.

  10. In economic parlance they call this opportunity cost.

    What are you missing out on by choosing either:

    1. Storing your solar energy in a battery
    2. Sending your solar energy to the grid

    I know which one I choose for now. To be clear I say “for now” because battery tech and prices are constantly changing.

  11. Contracts = spinning reserve. Realist is correct. They do not shut down coal fired generators for small or transient reductions in load. Your argument may be theoretically correct but its not how the real world and commerce operates, thats the big hurdle we all have to get over.

    • Whilst that’s true, baseload is not what responds to peak load. Therefore I’d say Ronald is on the money. Gas peakers and hydro are mainly used to balance the peaks. Both of these generate much fewer emissions than coal and with the amount of energy/waste that results from batteries, they simply can’t be environmentally friendly with our fossil fuel dominated grid unless you top your battery up fully with solar… most Australians don’t have the roof space to do this.

      If you look at AEMO’s stats you can see the price doesn’t drastically drop as much at night ever since Hazelwood went offline. As such, other coal plants like Vales Point and Loy Yang will constantly be on meeting demand. These do throttle a bit at night. (Around a 6 hour reduction time to reduce turbine output)

      • An open cycle combustion turbine has similar emissions to a coal station. Some really expensive ones can be better, (due to exotic high temperature metals being used), and some like the ones SA has just bought can be worse than coal.

      • Caroline Copley says

        Hydro is not at all environmentally friendly as I pointed out in another post, due to its variable and serious environmental effects.

    • Ian Thompson says

      Hi Peter R

      Just a question…

      So, if the generators cannot or do not reduce generated output, where does the excess energy go, that is not required by the grid during a dip?

      Is it dumped to a huge resistor bank?

      Or, is it simply that they throttle back the steam pressure to reduce turbine output as required, so if the burners don’t throttle back the excess heat energy produced is stored into increased steam pressure in the system – to be recovered when demand increases again?

      I do understand the principle of “spinning reserve” – and that this wastes energy just keeping turbines at the ready.

      Much like SA has been keeping gas-fired plant running at ~ 0.5 GW, even though their wind power exceeds demand (and they are exporting power)?
      Found that by monitoring this site:

  12. Gentlmens
    I have just ordered a 6.1kw system with a 9.6kwh battery. I’m told the system will produce approx. 20kwh of power per day.
    Given that without the battery, I wouldn’t bother to install the panels/inverter and I would continue to buy all my electricity from a coal powered grid, How am I harming the ‘vironment by not purchasing 15kwh per day?
    I know I’m thick but aren’t I only being inefficient with solar power that would otherwise just heat up my roof?

    • Ronald Brakels says

      Hi Leon. As mentioned, the extra emissions resulting from using batteries is only small compared to the reduction in emissions from rooftop solar, so overall there will be more benefit than harm. Just less benefit than if you had solar alone.

      Provided you are on-grid, any surplus solar electricity from your rooftop will be sent into the grid for other people to use and lower fossil fuel generation. If you are off-grid, then batteries can definitely result in less emissions than using a generator.

  13. Electric vehicles? I am amazed that people keep saying (indirectly) that they want to keep importing oil from Saudi Arabia!

    No matter how coal-intense your grid is, if you get an electric car, you are reducing oil imports from Saudi Arabia and thus tackling the trade deficit.

  14. Re Swedish Study:
    The IVL study examines all known EV battery ghg papers, where range of results is wide. The paper may support Ellingsen’s 2013 figures, but the lower figures pre-date that study by several years. The IVL conclude that battery ghg lies between 150kg/kWh and 200kWh. 175kg/kWh is the median value, and within the range of the majority of the studies. Manufacturing processes are now mature, with little left to be saved.
    Expected lower battery prices, won’t encourage investment in renewables, but are likely to lead to production shifting to where environmental controls are less stringent, or the robbing of available renewables, so that Peter may pay Paul. There is little reason to think the 175kg/kWh could be substantilally lowered, let alone wrong.

    Popular Mechanics:
    The IVL stressed that battery size is an important factor, citing the 100kWh Tesla battery, which produces 17.5 tons.
    They do not condemn EV’s, but the effect of large batteries. There must be a point where embodied ghg, exceeds the gains from reduced tail-pipe emissions, relative to an ICEV. The EV must be driven long distances to equate to an ICEV, where total ghg of both vehicles increases. EV’s not driven long distances, simply add more ghg.

    The Popular Mechanic’s article took the 17.5 tons of the 100kWh battery, and compared an Audi A8 4.0, which produces 7.3 tons ( 6.2 tailpipe + 1.1 tons upstream) over 15,000 miles (486g/mile).
    From those figures, the author concludes the battery’s footprint is ‘zeroed out’ at 2.4 years ( 35,950 miles). But, the 100kWh battery is attached to a car, which must be driven to ‘zero’ the ghg.

    The Tesla P100D will produce 300g/mile when powered from the general grid-mix, reducing the difference to 186g/mile or 94.000 miles ‘zeroing’ distance.

    However, the total would be
    P100D : 17.5 tons + (300g x 94,000) = 45.7 tons
    Audi A8:( 486g x 94,000 ) = 45.7 tons.

    That’s 6.25 years. When compared to the average US passenger vehicle’s emissions of 411g/mile (EPA) the figure is 10.5 years. The total emodied ghg of each car will worsen the result, but the IVL are correct concerning battery size.
    Was the company threatening to ‘destroy you’ also the producer of the largest
    capacity home battery?

  15. Ron, an interesting article. A couple of points:
    99 homes is a very small sample size…… and it’s in Texas not Australia.

    So, for example , the study doesn’t look at the efficiency / energy loss of traditional methods of energy transmission in Australia. Surely, in Australia with its relatively long energy transportation lines through wires from (mainly) coal fired power stations …this would be very important to examine (to compare apples with apples).

    The authors note that the Texas grid mix is primarily made up of fossil fuels. One way to start to make the grid cleaner is to encourage renewables so there are “under the table” benefits that may not be visible in a study such as this.

    Seems to me the bottom-line from Fares himself is where he states: “ If a homeowner is seeking to reduce his or her environmental footprint, adding storage would not make the household more green (in Texas) , but it shouldn’t be dismissed either. Solar combined with storage is still a lot cleaner than having no solar at all,”

    • “99 homes is a very small sample size…… and it’s in Texas not Australia”

      99 homes is enough to provide a valid data set, for all but the unusual.
      The data were collected every second, to provide high resolution data. For the grid, the researchers compared several regions, where there was a mix of many sources. It would be an odd circumstance where the conclusion didn’t apply.
      Solar + battery may be better than nothing, but even better without the battery. There isn’t an economic case, either.

      A 13.8kWh (PW2) battery will embody 2.4 tons of ghg. Australia’s grid produces an average 1kg/kWh. Importing the battery is like importing the ghg of 2.4MWh of local generation. Add to that, the waste from inefficiency over the warrantied 38MWh.

      Home batteries were suddenly launched, along with claims of environmental benefits and economic return, but without proof. The first claim may appear to be plausible, but the peer-reviewed paper refutes that claim. The other is obviously not true, either.

      • A Thomas – 99 homes is a very low sample. You need to study statistics if you disagree. “Solar combined with storage is still a lot cleaner than having no solar at all,” came from the author of the study.

        • 99 sampled enough for the 95% calculated confidence limits, and certainly enough when the method is comprative and not absolute.

          Despite ypur criticisms of the paper, you offer its conclusion in support.
          It’s not much to offer that adding a battery to clean solar, degrades it towards
          having none at all.

          • Yes ……far better to not have a battery and be forced to draw the additional power you need from (probably) coal fired power stations and accept the well documented loss of up to 15% of the Joule effect in transformers and power lines (the energy is lost as heat in the conductors)….. Yep those poles and fires are just so efficient by comparison to home batteries.

          • Losses are a red-herring.
            Where the aim of solar/battery is to reduce household grid demand, ‘target zero mode’ transmission losses have little to do with the ghg increases.

            If those losses were directly responsible, solar alone would also increase ghg.
            There really can’t be a distinction between “battery” energy and “solar” energy as far as those effects are concerned. The primary reason solar reduces grid ghg, is the reduction in household demand, when replaced by solar.

            The reasons for the increase in emissions due to the battery’s inclusion are:
            “The change in grid emissions from the addition of home battery energy storage is caused by two separate factors: the additional energy consumption required to covers storage inefficiencies, and the fact that storage shifts electricity demand in time, and alters which generators are used to provide energy not produced from rooftop solar panels”

            For the mentioned “target zero” mode, the battery works with solar to reduce household grid demand, and does so throughout the day. As a consequence, charging losses waste solar that could be used to offset grid demand. That lost opportunity increases grid consumption by an average of 8%.

            The second reason, is due to time shiifting of stored energy, which increases the marginal emissions of the grid’s generators. It’s the time shifting that solar can’t do, that produces that second effect.
            “When storage operates under the ‘target zero’ mode, its mean emissions impact is 160 ± 7kg CO2, 0.05 ± 0.02kg SO2 and 0.05 ± 0.01kg NOx per household per year.”

            Solar also increases marginal emissions, but the overall reduction in ghg from reduced consumption is much larger. The conclusions are relative to solar, and the worsening effects of the battery.

    • AEMO publish the losses on every line for an average days profile of generation and demand. (they need it to make the dispatch equations work)

      On average around the country it is under 10%. Given Texas will also have some losses in any event, the differences will hardly sway the result

  16. Dara Bortman says

    So, here in Pennsylvania and NJ in the US, we install battery backup for grid-tied systems as an alternative to a generator. So it’s not for either of the reasons mentioned above – it’s solely to deal with times when the utility power goes out to run critical loads in the home. So, in that case, the customer essentially has a battery that sits fully charged 99% of the time just waiting to be used in the case of an outage. The battery backup option is generally more expensive than a generator – at least one that would do equivalent work in the home – just running critical loads and not the entire house. So customers who go that route already know they’re paying a premium to avoid getting a loud, dirty generator that would require filling with some type of fossil fuel to run for any length of time. I’d be interested to hear your analysis as far as the comparative environmental harm in that situation? If we assume someone would either be getting a generator, or using battery backup? Would love to hear your thoughts. Thanks!, Dara

    • Ronald Brakels says

      Hi Dara.

      I think a big problem with having battery systems on standby for power outages instead of a generator is the standby energy consumption of the battery system. While self discharge rates can be quite low, I’ve heard of people discovering that their battery systems uses a considerable amount of power when just sitting there doing nothing. While better engineering should be able to reduce this problem, it makes me think the environmental impact of battery systems installed just for back up could be very high compared to a generator that is rarely used.

      • It would be interesting to see analysis on that. And to compare that to the generator that was the alternative. Because in these cases it’s a choice between getting the battery backup or a generator run usually with gas or propane. Not a choice between battery backup and nothing. Also, do you think there’s a difference in the latent energy use if the battery backup is ac-coupled vs dc-coupled?

        • Ronald Brakels says

          I would definitely expect AC coupled battery systems to have higher standby draw. Because DC coupled systems were originally designed for off-grid use, every watt-hour would be considered valuable. But AC coupled battery systems, since they’re grid connected, could get away with a high self consumption rate as very few people will even think of checking what it is, let alone work out how it affects the economics or environmental impact.

        • Caroline Copley says

          Dara, by gas you are referring to what we call petrol I gather. The main fuel used in home generators in Australia from what I can gather from ads here is diesel. So mostly when I see ads here in Australia for off-grid solar systems, which I have to buy where I’m going, if they involve a generator it is diesel, and I have yet to see an ad for a generator backup which uses petrol (your gasoline) or anything else- I haven’t seen one yet for gas (propane). And the solar systems themselves wouldn’t run an electric toothbrush so especially in winter in the bush you’d be hammering away on the diesel to keep warm! Completely and utterly undermining the whole point of the exercise one would think.
          It seems to me that there a lot of companies on the solar bandwagon, but even some of the more reputable ones don’t seem to have grasped the concept of emissions reduction exluding diesel. They just see economics which is hopelessly inept when talking about environmental consequences. Even fewer realise that environmental effects don’t stop at emissions, although a few companies are experimenting with alternative battery types. So I’d say Australia is on a giant marketing curve rather than a giant emissions reductions one, especially with the government ineptitude that seems to go along with it. Thus the pollies have achieved their aim of “market-driven” but the truth is it’s not driving us anywhere!

  17. Lawrence Coomber says

    Ronald you have emphasised the most important of all subjects in the global solar PV generation debate and that is system efficiency, and energy conversion efficiency in particular. Another not often discussed subject is the ‘Energy Equation’ which underpins just about everything relevant in energy science discussions such as this one of yours.

    So if system efficiency (accumulative efficiencies in the system chain) is deemed to be the most important performance starting point for everything happening in downstream system hardware, why is there not more obsession and focus on the orientation of solar PV arrays by system design engineers and installers, to ensure that maximum efficiency (or moving closer toward maximum) is realised?

    Most systems I have run my experienced eye calculator across (many in many countries) can be considered as starting their unproductive life at from 2 – 30% of what they ‘could’ and ‘should’ have been starting at!

    So my questions are (1) Might one reason be because the global PV industry has been more interested in riding the wave of near hysteria in solar PV panels installation (with overly generous Government subsidies for installing it anywhere irrespective of any performance standards being met) instead of directing some research and design effort into cost effective and fit for purpose alternative PV panel mounting technologies, to better deal with this seemingly critical issue?

    (2) From a system design standpoint, what would you consider the minimum efficiency standard be for a solar PV orientation (against the optimum – non tracking percentage determination) before the system should be given approval to proceed to installation that will be accepted for Govt subsidies and FIT’s.?

    Thanks Ronald you have presented an interesting topic.

    Lawrence Coomber

    • Ronald Brakels says

      Hello Lawrence.

      Those must be some pretty horrible installations if they only producing 2-30% of the realistic maximum that could be expected. But then I have seen photos from the US where panels have been installed under almost permanent shade and the installer has put a big sign up boasting about how they were the ones responsible for the travesty.

      Fortunately, the Australian solar industry is more professional, although there are of course still some bad eggs.

      (1) In Australia we are locked into laying panels flat on roofs. (With a gap for air circulation.) This isn’t about to change, especially as the cost of PV falls per watt. So while improvements in technology for mounting panels flat would be welcome, improved tilt racks probably won’t see a lot of use here.

      (2) Here feed-in tariff subsidies are long gone for new solar and Small-scale Technology Certificates (STCs) that are part of our Renewable Energy Target are being phased out. So any potential benefit from increased monitoring is disappearing and so I doubt it would be worthwhile.

      Economically speaking, the most efficient course of action would be to make all generating capacity pay the full cost of its greenhouse gas and other forms of pollution externalities. Anything less than that is really a second best solution, but if that’s all that’s available, that’s what I’ll use. No point in letting the perfect be the enemy of the good.

  18. Oh Ron – there are so many that just want to believe their investment or proposed investment is good for their pocket and good for humanity. (or just to get back at greedy ‘power companies’)

    Sadly the nation doesn’t run on peoples beliefs, nor no the rules of maths and physics.

    • Ain’t that the truth. Paint the utilities as greedy deamons (though indepensible).
      Convince the public to spend the money they would have paid to the utilities for energy, upon batteries, where payment is upfront, and the owner supplies the energy. Then, thank you, and goodbye, save for the vague warranty.
      Someone gets the finger, all right.

  19. The argument is correct in as much as saying exporting the excess from solar during the day is beneficial.
    If stored it is then used which results in a 90% reduction against 100%.
    So use battery and yes it will only for argument sake reduce emission 90% of direct export however have a system that is bigger than usage and storage needs with exportation of the excess.
    In this instance the daytime usage is covered and the majority of night time use is covered and excess to that is exported now that has to be a lessening in emissions.
    So using the last example this only has that battery storage part being 10% worse, however the more of this example used a potential 50% at least reduction in emissions should result assuming a 40% day 60% night usage.

  20. OMG what a completely waste of time writing this garbage!

    It’s like saying let’s not build electric cars yet because it’s going to be charged off coal.

    One step at a time Ron.

    If we all had batteries at home to cover our personal consumption than your argument wouldn’t stand. So let’s not start buying batteries and installing them and making them cheaper and getting more dollars and attention on battery research technology because currently it wouldn’t be as good for the environment OMG ?

    • Finn Peacock says

      G’day Miles,

      Ronald says in bold type near the top of the post:

      “This is not me saying don’t buy home battery storage if that’s what you want.”

      If you want to buy a battery – go for it. I bought one. It is fun to own a battery if you are into that kind of thing.

      As for helping reduce battery costs, battery technology and its cost reduction is being driven by electric cars and grid scale storage.

      • Definitely electric cars are help too. Electric cars have bigger batteries and weight concerns unlike energy storage systems.

        ESS is a step closer to helping the environment regardless of the disinformation written above.

        If you really care about the environment focus on the largest cause and not the smallest you could find using a magnifying lens.


    • Miles,
      Consider the mining, processing and manufacturing that makes a home battery, so that the owner can perhaps deny the energy supplier of a few hundred dollars per year.
      Is that an economical process? It isn’t, so the battery owner pays for the real costs. Cell costs won’t fall much. What you may be seeing reported, is the reduction in costs of large cells, that were formerly in low volume, but they will reach a bottom price, very soon.

      Small EV’s can be of some environmental benefit, but range is still too short to replace the general ICEV. Adding large motors and large batteries, may provide long range and performance, but the environmental benefits are negated.
      Hybrids such as the Prius, can offer lower emissions, coal or not. Tesla jumped the gun, by simply enlarging the EV, to claim a fetish market, and exploit ZEV credits that were intended for cars that reduced emissions.

      Home batteries are another example of introducing a product that has no immediate benefit, and will be redundant should the grid becomes cleaner.

      The IVL EV battery study and Fares’ home battery study, expose the opportunism that is at work. As Finn says, there are better ways of spending the money.

      • You just don’t get it. Your missing so many points on the progression of technological advances which happen when investment happens, batteries are helping the next generation to occur.

        Every car, plane, truck will be electric!

        It’s an electric revolution ffs.

        P.s the grid won’t became cleaner with so much abundant coal. It will only by a decentralised energy source and large scale farms

        P.s.s Tesla Model S does 500km already, plenty for the average daily commute of ~50km (with no pollution)

        • Lithium batteries date to the mid 1970’s. The version commericalised in 1998, did not consider the environmental consequences, but just the advantages for portable devices. Those cells have been driven to minimum cost by long standing competition, investment and development, where the expected future was the current date. Although larger power cells exist, there hasn’t been a significant consumer market for them. Now there is, so prices of that type of cell have fallen, but they remain much the same cells, made in the same way.

          Ronald may think there can be improvements that may sigificantly lower the ghg content, but the recent IVL study shows that the later studies, and more recent data, suggest even higher ghg figures, and not lower.

          Do you think it would be worthwile spending the limited renewables, on mining coal, so that its claimed ghg figure could be lowered, when the renewables could be directly used to replace the coal? That’s what expending renewables to clean up batteries would represent.

          EV’s have their place, but the larger the battery, the larger the ghg. A hybrid solves the range and fast fueling problem, without large batteries, and the peak power demands of charging them.

          In Australia, the 100kWh Tesla would add the 17.5 tons, and signifcantly higher ghg/km than a hybrid such as the Prius. EV’s are rather old tech, and so are ICEV’s, but the Prius is the result of development and investment, too.

          The Fares paper isn’t a hoax. It is a thorough study, and denies the tales told by battery salesmen. It’s not so hard to realise that there is money in selling large quantities of batteries, and there are environmental concerns to be milked.

          • PS.
            Home batteries have been around for decades, but the public showed little interest. When the Powerwall was launched, suddenly, there were buyers willing to pay more than anyone thought plausible. Other manufactures quickly siezed the opportunity, and produced batteries, ptiched at prices similar to the Powerwall. Like this blog, home batteries compare price, warranty etc, relative to the Powerwall. Prices may fall as competition reduces margins, but prices won’t fall far enough to become economical for the owner.

          • Funny that, people now buying battery storage as we get gouged by the utilities with the most expensive power in the world.

            Thanks to Germany starting the solar revolution and China’s mass production we now have cheaper and cheaper source of energy. 1+1= no brainer.

            It’s already economical! What else can you buy that pays its self off? How your new car going?!

            Hybrid is for people who are to afraid to make the full step to the future. Electric cars have 90% less parts, less things to go wrong & less maintenance.

            The sun is the GREATEST ENERGY SOURCE IN THE ENTIRE UNIVERSE. Solar, with batteries and an electric cars allow you to tap into that ecosystem. Let me know when you find a greater, cleaner, safer, more reliable energy source.


          • Caroline Copley says

            Other than the comments I made above about the effects of mining on the ecosystem, I would like to point out to Miles that the Sun is a physical system. An eco-system is an ecological system which is defined largely by living components although it can include their relationship with the physical system, such as nutrients, solar input and so on. Therefore you can’t have an ecosystem with the Sun only, it’s like a driverless bus without anyone in it, it is not a biological system but a physical one. Also you can’t examine environmental damage without looking at mining for materials for solar such as habitat destruction, effects of hydro on streams and species, clearing for windfarms and so on. This has to involve the “life cycle” of the products, not just a narrow examination of emissions at a late stage of the cycle. Otherwise the whole thing becomes farsical. No more so than those solar companies who sell solar components and advise “diesel generator backup”. Never mind the pluses and minuses of adding to the grid or not, with such backup you can’t fail to be creating emissions, which is why diesel is being banned for cars in Europe. This all really makes me think that people not only don’t understand environmental effects and what an ecosystem really is (i.e. it is not a computer network as often referred to), but that the whole argument has gone somewhat AWOL. Determination of environmental effects, effects on the ecology of the planetary system, that is on the living components, needs to be examined in entirety not just in tiny little segments.

      • Yes, the sun is an available energy source, but requires process to produce electricity. Solar panels have a relatively low embodied content, so produce low ghg/kwh figures, but how that energy is used, can undermine or negate that benefit. In the extreme, solar-generated electrical energy could be used to heat coal to combustion, and produce a lot of ghg.

        I expect you would object to that, but there may be less obvious ways in which that same process occurs. From manufacture, batteries are one of those less obvious ways, even if they claim to later ‘recover’ the ghg when in use. Do they?

        The Fares paper says home batteries don’t, even if the embodied ghg is ignored, meaning it doesn’t matter if the batteries are manufactured using renewables or not. The embodied ghg is in addition, and another failure of home batteries to meet their claims.

        EV’s are not all the same. Like the home battery, some may not live up to their claims. EV’s with large batteries, not only manage to undermine solar, but do so to the point where they can’t match a hybrid or even an efficient ICEV.

        There is freedom of choice. It works both ways. The freedom to buy a large EV like the Tesla, while ignoring the facts, or to use the facts to freely make a choice. Home batteries too, of course.

        • Most people would understand the simple equation Solar and batteries are good for ghg! Better than burning coal.

          Tesla are selling a US $35k (Aud 50k) for a model 3 which gives you 220 miles /350Km a charge, beats in Petrol engine or hybrid for economy, maintenance and 0-100 speed – Your right, they are not all the same – Pure Tesla electric cars are superior

          Welcome to the future

  21. Actually my 50% is rubbish.
    To use 100 kWh of power the generator has to produce more due to transmission losses so use 5% as that figure.
    The hypothetical house uses 100 per day 40 during the day and 60 at night.
    The transmission from the generator is 105 to cover this.
    Solar produces well over 120 a day with a big enough system.
    40 is used during the day and 60 is stored for later usage.
    Of that 60 there is a 10% loss due to round trip efficiency to battery etc.
    There is also a 5% gain due to transmission loss so the nett is a 5% loss.
    So looking at the figures 120 produced saves @ 5% loss in transmission a total of 126 the storage is 60*10% = 66 so the outcome is neutral.

  22. Derek Harbison says

    Ronald, that does it. I am putting you up for a comic writing award! Love your posts and I always get a laugh from them. Keep up the good work and stay on the Left Hand side of things. It will never let you down.

  23. I Love soler says

    This may sound uneconomical but I’m sure in the long run ( as battery prices reduce ) this will be economical….Here goes. If I produce say 30 kwh / day, use 5 kwh of that during the day then for arguments sake use another 5 imported kwh at night in theory ive supplied 20 kwh to the grid / day. Now if I install a 2nd solar / battery system to run my house on I will export the total 30 kwh the original system produces then generate and store the 10 kwh my house requires. the generous feed in tarriff allows excess cash generation to pay for said systems and more quickly with the full 30 kwh being exported…. so shoot me down but how is that not better for the environment

    • Ronald Brakels says

      Installing solar plus a battery is better for the environment than doing nothing, but solar alone is even better because no electricity is lost charging and discharging the battery and at the moment all solar electricity sent into the grid reduces fossil fuel generation. So if you were determined to provide the maximum environmental benefit you would install your second solar system without a battery. But, if you wanted a battery, then you could install one and be confident that you would be cutting emissions by much more than you were increasing them.

      (Of course, in the future, enough surplus renewable energy may be created at times that batteries become an environmental plus, but unfortunately it will take time to get there.)

      • Peter Nemere says

        This is the point Ronald. Batteries cut emissions by a lot and the marginal increase in power your arguing with your 10kwh/9kwh thing is to irrelevant because you’re now using solar all night and not drawing say 6kwh from coal power.

        But during the day you’re using an extra kWh of solar to charge the battery.

        The grid has efficiency loss too which you’re not advertising… So that “wasted” kWh of solar sent into the grid would not stop 1kwh of coal power.

        But the main point is, at night fossil fuel is king and every kWh generated is dirty.

        Using batteries makes your night time usage clean.

        We have to take aim at night time emissions and make more power plants redundant if we want to see GHG reduced. While that isn’t done solar is only a cute to thing that happens during the day (while coal plants are still producing CO2 to keep them warm for night time but maybe not as much power because of solar) then the whole night is coal powered.

        Batteries completely offset a households night time energy usage, to cover your criticism the household can put up 2 extra solar panels. But the way of the future is batteries and every solar powered house in Australia needs to buy a battery. If this happens all our coal plants can shut down and we can build large grid tied panel farms to ensure batteries are charged from solar energy on cloudy days.

        • Peter, “target zero” works like this:
          1) The battery is restricted to charging from solar, where there must be solar in excess of house demand. That excess solar is usually returned to the grid. Therefore, charging lowers grid returned power.

          2) The battery does not discharge into the grid, but operates to power the house. The battery only discharges if there is grid demand (otherwise solar powers the house). Therefore, discharging lowers grid demand.
          The above, are the only occassions when the battery interacts with the grid.

          Over time, battery charge and discharge power, balances. If the battery were 100% efficient, the battery would have no net effect upon grid power or ghg.
          In that case, as far as the grid is concerned, solar + battery behaves just like solar only.

          But, battery inefficiency upsets the balance, producing a net grid demand, equivalent to increased houshold energy demand, and additional ghg above solar alone.

          If the grid were powered by one stable source, it would not matter when the discharge and charge events occured. The total increased ghg would be the same, for any time or day.

          But, grid mix changes throughout the day and time of year. As a result, when the charge and discharge events occur, influences the “marginal efficiencies” of the generators, and increased NOx and SOx, even if the battery were 100% efficient.

          Overall, the battery increases ghg, NOx and SOx emissions over solar only.

  24. Ron you state:

    “Because energy is always lost when charging and discharging batteries, homes with them use more energy than those without. The difference is made up by increased grid generation.”

    You then go on to state “…if your goal is to be green you are far better off expanding your rooftop solar capacity than getting batteries.”.

    My question is this. If :
    1. this difference if you don’t have a battery has to be made up by grid generation (must be true), and
    2. if this generation is based on coal fired generators (likely to be true), and
    3. if the lines and poles themselves for these coal fired generations are themselves going to loose between 10 and 15% of the energy thru transmission and distribution (true); and
    4. Without a battery all of the above are likely to occur (probably true).

    ….what is the point of the study (if the alternative is worse than the no battery proposition) ?

    • Ronald Brakels says

      Tony, if rooftop solar produces 10 kilowatt-hours of electricity and it is sent into the grid it will reduce fossil fuel generation by 10 kilowatt-hours or very close to it. If the 10 kilowatt-hours of solar electricity is instead stored in a battery system that has 90% round trip efficiency than fossil fuel generation will only be reduced by around 9 kilowatt-hours. As a result, rooftop solar without batteries will reduce emissions more than rooftop solar that uses batteries. So not using batteries is the better option as far as emissions are concerned.

      • Ronald,
        Sorry, but the paper does not directly claim that adding a battery increases ghg because of reduced returned energy, but quantifes the difference between solar only, and solar + battery, for the sum of all effects.

        “>The change in grid emissions from the addition of home battery energy storage is caused by two separate factors: the additional energy consumption required to cover storage inefficiencies, and the fact that storage shifts electricity demand in time, and alters which generators are used to provide energy not produced from rooftop solar panels<"

        The free supplement is useful. It provide some limited data for solar only, while showing the changing effects of both algorithms, according to circumstance.

        Some (free) charts are available under the 'figures' tab, top right.

        'Target zero' operates to minimise household grid power demand. Chart 2, found under 'figures', shows that under 'target zero', both peak power demand and return are lowered by the battery (blue), relative to solar only (black) – yet the battery increases ghg. Since both demand and return power levels are reduced, the increased ghg could be due to either, or both.

        Firstly, the model uses household consumption and solar data, to find the total houshold annual consumption and related ghg, where the effects of returned excess solar are included. Then, the same situation where the battery is included. The increased ghg is relative to solar without a battery.

        The battery's inefficiency wastes energy as heat, but energy can only be counted once. The lost energy either increase household consumption, or reduces the retuned energy, but not both at the same time.
        The paper ascribes battery losses to increased household consumption, but there is a second effect, according to when demand is made, so the effect of 'time shifting'.

        Throttling a coal generator's output, lowers total coal consumption, but can move efficiency away from the optimal, so increasing ghg/kwh, defined as 'marginal emissions'. The authors also examine the case where the battery is 100% efficient. The battery's ghg is reduced, but not NOx, because of the residual effects the battery has upon marginal emissions.

        The situation is complex. Household load, solar input, operation of the algorithms and grid mix, change throughout the day and year, and why detailed modelling is necessary.

        General arguments around lowered returned energy, and throttle generators are inadequate, in either support or denial of the conclusion, but serve only to confuse the situation, as personal hypothesies are offered. The paper is the peer-reviewed conclusion, and it says batteries increase ghg.

        Even with an impossible 100% efficient, batteries would still increase NOx and SOx. Presently, an AC coupled battery at 89%, must include the solar inverter's 96%, to total no better than 85%.
        Battery manufacturing ghg is large, but will never be zero. If the grid cleans up, the battery won't reduce ghg then, either. There is no present, nor future environmental benefit, to be had from home batteries.
        I would be interested to hear you reply, Ronald.

        • Caroline Copley says

          There is if you are off-grid which was not referred to in the blogs’s deliberations or presumably the scientific paper. I have a choice, between a $30000 hookup to the grid or a $30000 hookup to solar involving large batteries in a cloudy area. Large batteries etc. that involve mining, possibly destroying rainforest and thousands of species somewhere directly. One choice involves batteries and panels with their mining implications and one involves wires and coal mining. Economically for me these are more or less equivalent, but I have yet to do the fine detail to know for sure. At least one reduces emissions as it does not involve connection at all, although it might lose all of its advantages due to habitat destruction for components, which raises the carbon footprint astronomically. These things are not simple, and certainly TYPE of battery and the way the panels are produced is very important. A small solar setup using a diesel generator often is a bit of a joke isn’t it? The alternative to diesel if you are off-grid is to increase the battery bank significantly, especially if like me you have to have storage as it is not that sunny in rainforest locations. So even if you are off-grid it is still going to have an environmental impact from mining for components, and usage of generators. We need to change how we think about what is an “environmental effect” back to what it used to mean, rather than equating it to emissions full stop. That is so blinkered I haven’t got the words for it.

  25. Dave Angelini says

    I am with Dara and her logic! In our small town 5,000 people were evacuated for 7 days because a nearby wildfire shut down the transmission lines. Very few people had enough gasoline to run their generators and so they had to leave. The police would not let them back-in until the power was up. The dump was full of refrigerators ruined by food spoilage.

    The ones offgrid like me and some of my grid townspeople with solar/battery systems were fine. The people with solar roofs all had to leave. In many cases there are not enough fire people and 60 homes were lost because there was not power to run pumps and sprinklers.

    The cost from emissions for the wildfire or “bushfire” as you guys say was way off the scale. Probably 5 years of emissions on the day it burned 19,000 acres in an hour.

    I am still running the LG RESU10 on Schneider Solar gear and it earned its keep the week of the fire!

    • Caroline Copley says

      Yes, good point, the need for backup during fires but especially for power to fight them. People in the know have a sprinkler system with a petrol pump, but there is no reason that solar technology could not take over that usage of polluting fuel through battery banks. There’s a startup for someone, as lots of bush folks have sprinkler systems. We all loved a conservationist and her husband killed by the 2009 Melbourne fires caused by transmission lines, where the lower naturally dry region was cleared of bush thus allowing grasses to takeover and dry in the Sun. One spark into all that grass sent the whole thing tearing up the mountains, as fire will do, like a volcano, and no-one stood a chance. Once something like that gets started, grid or not, many people and homes will not survive. But if by chance your house does survive it is nice to know you have power. Similarly in a flood where I was stranded once, wet and cold, for 3 days in a flood as the grid went down of course.

      I might add though that CHOICE of battery systems might be important, as it is for home construction materials. For example, think of the Samsung battery and then send a volcano towards a large version of it! There are actually differences in environmental effects of batteries in terms of mining but also in terms of their safety in a fire. I am not planning to test a lithium bank in my new off-grid installation up whoop whoop, where it will be me and the sprinklers and that’s it.

  26. Dave Angelini says

    Adding on, the LG Resu10 is about 96% efficient charging and 95% discharging about a 1KW load of cooling and house loads. Once the battery is full it uses about +/- 5 watts. At certain loads I have seen 98% during the day.

    This is the 3rd big wildfire we have been thru and the efficiency of this battery is amazing when the sky is full of smoke during the day. At night running the cooling to keep the smoke out is also a game changer for us. Our old system was between 80% and 85% on its best days/nights.

    Once the power went out in town, all the gas stations could not pump gasoline for 7 days. I am not sure of Australia, but here in the US they can’t make you leave if you stay on your property. The little secret is that there never are enough engines in rural areas for structure protection. If your property has the brush cleared and has decent level of fire safe construction,
    It is often better to have a person spray it down, go inside when the fire passes, and go out after and fight the spot fires. This could also kill you and so you really must have it safe to begin with!

    Sorry to derail the thread Ron,
    but I think it is worth it as our hot summer climate is like alot of yours. Cheers!

    • Caroline Copley says

      It depends which State of Australia you are in and sometimes the circumstances but there are usually not mandatory evacuations, but recommendations in advance to prepare or leave. The big issue is houses where embers get under the house or under the eaves. Regardless if you do live it is much nicer to be able to make a cuppa with the solar battery bank in action!

  27. Caroline Copley says

    Hmm I am examining which batteries to buy to reduce their impact on the environment. The aspect of things that was completely ignored in the article is mining. Emissions does not equal environmental effects, it is only one part of it, but it seems to have taken over the term altogether, so people don’t understand that environmental effects can mean something else aside from emissions impacts!

    The removal of large swathes of rainforest or other high quality forest by various mining companies, notably Australian ones, has a huge environmental impact, and there is an immediate reduction in carbon but also many other nutrients, as well as water from the system, that can take decades to repair. Let alone the impact on thousands and thousands of species in such species- rich locations, some that may exist in very small locales and are unknown and will never be seen again.

    So far I am thinking that the Aquion saltwater or Vanadium systems might be the best in terms of mining impacts. Of course major companies selling these went broke because people are interested really in money and emissions and not the environmental effects of mining. On that score the Zinc Bromide might do not too badly.

    The biggest joke is those companies selling miniscule solar systems so that people off-grid will have to rely on diesel generators which are highly polluting in terms of emissions, whilst Europe is banning it in cars! Lithium mining destroys salt lakes which are sensitive areas also, and this may have ramifications for groundwater etc. The main direct impact on the environment of batteries is in terms of habitat and biodiversity which then has indirect ramifications to do with carbon emissions but it is all environmental impact. Great swatches of solar panels or wind farms also don’t do much for ecosystems if they involve clearing large areas. There needs to be a bit of a wakeup call here.

    The other point is that you refer to the Nature article which is appreciated but you fail to note that this examination of connected grid systems does not apply to we off-grid types who do not add/lose anything to the grid, so it becomes a mute point. In that sense off-grid solar and wind installations are excellent, and battery storage is a necessity, particularly if you want to cut down on the use of harmful petrol or diesel generators! But there is always going to be the life cycle issue of where the chemicals are mined from and how. More batteries equate to more mining, unless recycled components and chemicals are used, and hence to potentially highly deleterious habitat destruction and species loss.

    Adani wouldn’t just cause emissions, it would stuff up an entire region’s habitat through vegetation removal and groundwater sabotage. Only a country that had completely lost the plot could allow it.

    • Hi.
      I got here by accident, and thought I’d say I like your attitude. However it pays to remember that ‘the environment’ is NOT a stable entity – ever. Whether human activities are involved in the inevitable changes or not is irrelevant… and in a few billion years or so the entire solar-system disappears into the flash of an exploding sun. In reality, we are here at all due entirely to changing environments/conditions. The bottom line to all of everything in existence is not conservation: it’s adaptation. (ie Survival of the fittest. It’s no secret that cockroaches were here before the dinosaurs, and will be here long after we’ve disappeared into the Abyss.) Much as I detest what’s been done to the world I’ve loved in just my lifetime, I do strongly empathize with your concern for the sentient elements of our ‘environment’, I’ve decided other considerations, over which we do have some control are more to the point.
      Never give up!

  28. Sylvia Jones says

    athomas (august 12, 2017 – above ) says ” Like this blog, home batteries compare price, warranty etc, relative to the Powerwall. Prices may fall as competition reduces margins, but prices won’t fall far enough to become economical for the owner.” : and the argument seems to still be used, unchallenged, to this very day.. It’s invalid.
    Of its proponents, haggling over “comparative prices”, one might ask whether they round up their cows from a muddy rock-strewn paddock in a $2-million RR, or make do with a ‘downsized’/much cheaper/more efficient cattle dog.

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