Do You Need An Efficient Home If You Own A Massive Solar System?

The average size of a residential solar PV system installed in Australia has grown significantly over the years, which raises an interesting question: Should owners of larger systems even worry about energy efficiency in their homes?

Energy efficiency in the home has always gone hand-in-hand with installing solar panels. After all, a dollar saved is a dollar earned, right? But making your home more energy efficient costs money, and as the price of PV drops, it’s tempting to just bang on some more solar panels to make up for that extra consumption rather than addressing the consumption itself.

And that seems to be happening if we look how the average system size sold in Australia continues to grow:

Average solar PV system size history

Average rooftop solar system size in Australia by month 2012 to 2023. Image: Australian Energy Council

Let’s pause to consider the ramifications of piling on the PV without a plan.

Some say that, as our solar PV systems grow even larger, we may be unwittingly succumbing to a phenomenon called ‘solar rebound’.

Solar Rebound: The Enemy Of Energy Efficiency

The rebound effect occurs when efforts to reduce energy use lead to an unexpected increase in consumption. It can happen because people, feeling the benefit of more efficiency, end up using more of the energy than before the efficiency improvements. It’s a well-understood human trait that’s been studied for over a hundred years.

Solar owners have their own special sub-category called “solar rebound.” This happens when, after switching to solar, they feel less guilty about their environmental impact, or can afford to consume more with lower energy bills, and so end up with an increase in gross energy consumption.

Free Energy From The Sun

Yeah, but it’s free energy from the sun! I should be able to use as much as I like!

Of course. It’s your call. Just be aware your actions may have unintended outcomes. For example, diverting excess solar energy into a hot water system is a practical idea. But if this action leads to piping hot water 24/7 that you didn’t previously use, it can easily escalate to more, longer, and hotter showers.

If your reason for installing solar is to increase your comfort level, and you’re aware of the additional resource use and willing to pay for it, that’s fine. On the other hand, if reducing your carbon footprint is your end goal, you’ve become a victim of solar rebound and perhaps gone backwards trying to achieve your goal.

Even though solar power is cleaner than fossil fuels, it still requires resources for production. No energy source is entirely without environmental impact.

Here’s another one: A proud new owner of a 15 kW solar system is grinning from ear to ear because he can now run his air conditioner from morning to night at a reduced cost. Yet he hasn’t once thought to draught-proof his house or upgrade his window treatments and roof insulation to reduce the air conditioner usage.

Exceptions To The Rule

Of course, there are exceptions to the rule. If your solar inverter is export-limited, you could argue that it’s more beneficial to self-consume curtailed electricity that would otherwise go to waste as long as it doesn’t affect your overall consumption habits.

Another exception: You’ve installed a whopping 20 kW solar array that’s way too big for your current needs, but you’ve put a deposit on a brand new EV that will soon be living in your garage. Your overall energy use will soon be less because you won’t be burning petrol.

20kw rooftop solar system

A residential 20kW solar system.

So here’s a question – As we pile on the PV, left unchecked, is there a compounding effect of people succumbing to solar rebound, or is it all a load of hot air?

What Do The Experts Say?

Anecdotal Observations

Tim Forcey is one of Melbourne’s top home energy experts. He has advised energy companies, governments, and thousands of everyday individuals. He is a regular contributor to publications such as the Conversation and Renew Magazine, is the founder of MEEH (My Efficient Electric Home) Facebook group, which has over 100,000 members, and is the author of the “My Efficient Electric Home Handbook.

I asked him if the solar rebound effect was something he’d noticed anecdotally.

“I’m not seeing much in the way of rebound with solar in Victoria.

 

You don’t get solar because you aspire to a big footprint. Or I’ve not seen that anyway. In fact, having solar has made lots of households far more aware and less wasteful of their electricity use. And in Victoria and some other places, having solar drives people to reduce or eliminate their gas use. And petrol eventually.

 

Also, there are lots of folks building big homes with large footprints. They’re going to do that whether or not solar is a thing, so they might as well whack on a big system. There’s no solar rebound there!”

Tim Forcey thermal imaging

Tim doesn’t mind getting his hands dirty checking for air gaps with his thermal imaging camera. Image: Tim Forcey

Research Articles

In October 2021, researchers comprising experts in USA energy and environmental policy published a paper in the online journal “Economic Enquiry” entitled “Electricity consumption changes following solar adoption: Testing for a solar rebound.

They concluded that instead of reducing overall electricity use, solar adoption actually increases total electricity consumption compared to households without solar panels. This increase amounts to a rebound effect of about 28.5%.

As I journeyed down this rabbit hole myself, I found many more academic articles in environmental economics or energy policy research that concluded similar outcomes. I didn’t read them all because they’re boring as bat shit, but there was a general consensus that the rebound effect is alive and well, although difficult to quantify due to indirect effects.

Bugger.

Key Takeaways

I’m with Tim, but… I’m not disregarding what the majority of researchers say. I’m sure most solar owners have the best of intentions. However, we’re all human, and solar rebound probably affects more of us than we’d like to think.

So, back to the original question: Do You Need An Efficient Home If You Own A Massive Solar System?

Given the susceptibility to the effects of solar rebound, it’s fair to say you should be equally mindful of home energy efficiency as owners of smaller systems or anyone who uses electricity, whether from a renewable source or not.

And now, with escalating grid electricity prices, especially after sunset coupled with the cost-of-living crisis, even if you have surplus solar to spare, energy efficiency matters.

But what if you also own a massive solar battery?

Let’s leave that discussion for another time.

About Kim Wainwright

A solar installer and electrician in a previous life, Kim has been blogging for SolarQuotes since 2022. He enjoys translating complex aspects of the solar industry into content that the layperson can understand and digest. He spends his time reading about renewable energy and sustainability, while simultaneously juggling teaching and performing guitar music around various parts of Australia. Read Kim's full bio.

Comments

  1. Kim, I think at least part of the drive to larger systems is from people living in legacy housing where the effeciency of the house is poor. Sure good quality ceiling insulation, draught reduction and more efficient appliances and lights are over time possible for most people but floorand wall insulation plus double glazing windows are very expensive speaking from personal experience.

    In these situations a 20kW PV system would cost far less and inverter rack storage is falling in cost plus EVs are able to effectively store energy as well.

    This would seem to make a compelling case for larger systems in this class of dwelling.

    • Cem Kalyoncu says

      When you have solar the aim should be at net 0. At that point you are mostly free to waste, even if it means using more.

    • Window treatments and roof insulation also require resources for production. Is it significantly less?

      • Anthony Bennett says

        Hi A,

        Blinds may be cheap, mineral fibre insulation has a lot of invested energy, double glazing involves a lot of glass the same way PV panels do.

        What solar does, that none of these other things are capable of, is push the needle in the other direction.

        We should all be looking for more modest, smarter, better built buildings. Reduce, reuse & recycle is a great mantra.

        However if we produce, with solar we can be truly proactive

  2. I am with Tim up to a point.

    As we get the SA PFiT it behooves us to export as much solar as possible. Metering and especially a whole house energy meter helped us reduce our energy use down from about 11kWh/day to a very frugal 4kWh/day (including inverter losses)

    Now we have some extra off grid PV and off grid storage that is even lower and we use more energy rather than spill it.

    However I don’t see the point in building a house to Passivhaus standard now that solar is so cheap. Or spending what can be a sizable amount on double glazing when sensible window treatments like heavy curtains can to the job.

    • Brad abernethy says

      I am in Canada, north of Toronto. We get far less solar radiation due to our colder winter climate. I upgraded our 55 year old home to very efficient years before considering solar. With each appliance purchase, we opt for the most efficient. The entire home is now electric, except for a back up high efficiency propane furnace . My hydro bill has stopped $2000 per year. We do not use more power since our 11 kw array was installed..matter of fact slightly less.

      • Yes sorry, I should have pointed out I am in Temperate Adelaide and we get pretty mild Winters but hot Summers. Pretty easy to manage heat with shading, behaviours such as flushing at night and AC while the sun is shining.

        • Tim Chirgwin says

          It is cheaper to build more compact homes, and uses less energy in the build (and less energy to warm or cool too), yet on the energy efficiency scorecard a larger house with more volume to wall ratio is easier to make “energy efficient”.
          Clearly worrying about energy efficiency is all nonsense if 1. We overbuild more than required. 2. There are smarter ways to utilise otherwise wasted opportunity energy using cheaper and more reliable systems, just as you have described.

          Larger PV is way cheaper than passive house standards and has the added benefit of offsetting more early and late daytime purchased power too,
          The air tightness of a home makes the biggest difference to heat losses in winter, and good (multiple layer) curtains (close fitted) are more efficient that double glazing. Many people decide to put in more expansive windows that are double glazed at huge cost on the misguided belief that they are well insulated, yet an uninsulated wall is better than a double glazed window.

          I run 4 freezers on wall timers to run on Pv during the daytime only, and my cost (lost FIT at 6c/kWh) is 18c per day for all of them, while if I ran off grid power anytime they would cost me $1.20 per day,… consequently I believe in big solar first, but block the draughts out as well.

      • Brad abernethy says

        Note that should be hydro has dropped $2000 per yr..BTW.. my roi is just 9 years.

      • Brad abernethy says

        It should state my hydro bill has dropped by $2000 per year..Also, our windows are double glazed, and in the case of our huge picture window, triple glazed.

  3. Lyle Essery says

    Good article. Its right to question some investments into energy efficiency considering a home has a big solar system. I area I’ll mention is hotwater. If you are on very low FIT or are export limited or even offgrid you dont get much benefit from producing more than the homes load. Hence thousands spent on a complicated heat pump could be a poor choice when you could just use a 4x cheaper resistive element storage HWS. As the extra energy it uses compared to a heat pump HWS is moot.

    • Don Firth says

      I agree Lyle. when my 14year old heat pump finally dies, I will reconnect the electrical input and just use it as a normal HWS. The timer I have had on it since inception will ensure it only uses middle of the day peak solar that is otherwise currently wasted from disallowed export from my 3 combined systems totalling 10Kw inverter capacity.

  4. If the increased electricity consumption is due to no longer using a wood or gas heater, gas stove and gas HW, the increased consumption is a good thing.
    Re the average system size data; does the system size refer to inverter size or PV panel size? Same question for many of the graphs on the SQ web site.

    • Kim Wainwright says

      Yes Matthew I agree. Also, re system size data – system size typically refers to panel size, not inverter size. 6.6 kW panels into a 5 kW inverter is referred to as a 6.6 kW system. The graph above are averages, so that’s why there are increments and not actual system sizes.

  5. David Issko says

    I have a reasonably large home of around 400m2 in inner SE Melbourne. 3 adults currently occupy the home. Single storey, the length of the house faces north, so I was able to have a 25.6kW PV array installed on the roof, most panels facing north with some facing west. East is street frontage, so no panels there.

    In fact, as the array was being installed, back in October 2021 to replace an old 4.9kW system, I asked the owner, who was chief installer, to squeeze as many extra panels as he could onto the available roof space.

    I have no regrets whatsoever in going as large as I have and would gladly stick a bunch on my south facing roofline. However, my wife, the boss says NO MORE PANELS!!

    We feel that due to the size of the array, we don’t feel the need for batteries at this time for our all electric home, but look forward to what Tesla will bring out by way of the Model Y Juniper, come 2025.

    When the question comes up in the My Efficient Electric Home (MEEH) FaceBook group, which, by the way, has well over 100,000 members, I always say go as big as you can with your pv array install.

    • Brad abernethy says

      I agree with the go big statement. The only complaint I ever hear from people with a solar array is they wish they’d gone with a bigger system that covered their yearly hydro use.

  6. We built our energy efficient solar passive house over 20 years ago. Initially had 2kW solar system which we replaced with a 7kW system about 2017. The old 2kW system panels were recycled to drive solar water pumps on local dams.
    The 7kW system is still working well and we added another 4.5kW on our garage with 10kWh BYD LiFePO battery in 2018. Total of 11.5kW solar hooked up to 2 x Fronius inverters and Selectronic Inverter.
    The system has worked well, we get ~$50-$150 per quarter from our power company for exported power, use no fossil gas and charge an EV. We do have a wood fire in winter for heating in the evening.
    Solar passive design well insulated with double glazing means most winter days no wood heating till near sunset. Summer use of air conditioning running mostly on solar in afternoon.
    Well designed energy efficient house is comfortable and with modern solar/battery costs with little in imported energy. This year so far we have imported 148kWh of grid power and exported 2.86MWh of solar generated energy to the grid.
    In the long run we are comfortable and independent of grid in an emergency thank to our Selectronics inverter power backup capability.
    Capital cost was about $40k a few years ago, but security of power supply, comfort and minimal ongoing power costs have made it a good investment.

    • Straight up incorrect and most people simply cannot generate enough to run a resistive element HWS. The energy they use DOES matter and emissions for heating water represent 7.5kGs a day average x 10,000,000 homes.
      That wastefulness has to go and it’s cheaper to buy a heatpump than it is to put solar panels to meet the load of an electric HWS, noting that 65% of the energy required to heat household water is used in winter when yield is 1/3 that of summertime.

      As heatpumps get STCs the cost difference is negligible to change to a midrange heatpump.
      Let’s not get confused with the Porsche end of town they represent a very small chunk of the heatpump market and make people think they are out of reach when in reality all heatpumps are great. (Just need enough compressor power to suit the family for a long life)

      • Lyle Essery says

        My lived experience differs from your comment about heatpumps . Firstly storage REHWS can hold 400l of hot water and are very well insulated ( compared to HPHWS due to their complexity) thus can keep water hot for nearly a week. Furthermore you can change out load of the resistive element to suit the size of the solar system and your needs. Also you can get REHWS with dual elements further increasing flexibility and you can usually also push the max water temperature of a REHWS to 75c further increasing KW storage.
        Even on cloudy winter days my 12 yo 6kw offgrid array ( now degraded to around 4 kw) can easily bring my 300l REHWS with 1800 watt element to thermal cutoff without having to get help from house battery. Not so great in rainy weather but the storage capacity is so that we can have no heating cycles for days and still have hotwater. May not work with a big family – horses for courses I guess but the little time you need to supplement inadequate solar with grid imports ( i my case imports from main grid tied solar array) generally is less cost than installing and maintaining a complex heatpump – even with government throwing in money via STC’s

        • Geoff Miell says

          Lyle Essery: – Firstly storage REHWS can hold 400l of hot water and are very well insulated ( compared to HPHWS due to their complexity) thus can keep water hot for nearly a week.

          Heat-pump hot water system (HPHWS) storage tanks are “very well insulated” too. In my experience the thermal loss characteristics are similar. It helps if the tank port fittings, piping and pressure relief valve are insulated too.

          Why do you need a 400 litre tank? Do you have a big family?
          Big tanks still have thermal ‘standing losses’.

          Split-system HPHWS can have a range of tank sizes to choose from, ranging from around 160 to 315 litres storage capacity.
          Example: https://www.sanden-hot-water.com.au/specifications/

          Lyle Essery: – Also you can get REHWS with dual elements further increasing flexibility and you can usually also push the max water temperature of a REHWS to 75c further increasing KW storage.

          Why thermally & structurally stress your tank unnecessarily above 65 °C?
          Why increase your thermal losses unnecessarily?
          Why increase the risk of instant scalding if your tempering valve fails?

          Lyle Essery: – Not so great in rainy weather but the storage capacity is so that we can have no heating cycles for days and still have hotwater.

          Indeed, a REHWS leaves little or nothing in reserve for other high energy demand appliances that you may need as well.

          In my experience, the remarkable energy efficiency of a Sanden heat pump hot water system compared with resistive electric & gas-fired systems is hard to beat, even in freezing winter conditions.
          https://www.solarquotes.com.au/blog/heat-pumps-explained/#comment-1630088

      • Straight up incorrect? Our 315L tank with a 2.4kW element will run for 3 hours or generally much less before the thermostats switches it off before the timer does. When it is just the 2 of as at home, it can be left off for 2 days and still be hot as you would want.As it heats the water to 70C and a tempering valve mixes cold water to bring it down to a legally safe temp it can deliver much more HW than its volume.
        Not many PV systems don’t have the spare 5 to 6 kW that is apparently the average used on HW. The complexity and failure rate of even expensive brands of heat pump make a long lasting resistive HWS an easy choice if you have solar PV.
        Get a small element such as a 2.4 kW. A 40 year old HWS system is heating the water where I am visiting at the moment.

    • Not sure how this discussion turned to Hot Water Service (HWS). The approach we used was to insulate the house the best we could, give our house good solar orientation with glass sliding doors facing North.

      Note initially we could not afford to double glaze these large North facing 3 panel glass sliding doors, but a few years ago we did double glaze them and the improvement was impressive.

      Our 24 year old Solar HWS still works, but is often boosted with element especially in morning. If doing it again would most likely get a hear pump HWS.

      Our advice is get as much solar as you can fit (11.5kW) and fit a storage battery (BYD 10kW) if we were doing it again. We would have even more solar and 20kW battery, but for now our set up with our solar passive house works very well.

  7. In economics it’s called induced demand. For example building bigger and better roads makes more people drive, and you end up with more cars and traffic. In water supply, more or bigger dams induces more demand for water, as people find new uses for it.

    I like many put a big system on in preparation for an EV, as you mention in the article. In the meantime we enjoy being able to hear the entire house for the first time since we owned it, at no cost. (We have a Powerwall 2.) We also installed double-glazed windows and have otherwise great insulation, so the heat pumps barely raise a sweat anyway.

    You don’t happen to know if people get the $300 rebate announced in the budget yesterday if they have zero electricity bills? 😉

    • We got the Dictator Dan rebate in Vic regardless of being in credit so it’s a form of tax credit that’s easy to manage for the govt.

  8. Erik Christiansen says

    As “should” is not included in my vocabulary, being a 70 yo bachelor hermit, the article sounds quite amusing. As current global de-fossilisation inaction aims us at +3.4 degC, maybe a billion displaced, hundreds of cities abandoned for higher ground, the current USD 1 trillion spent annually on the transition needs to be x5 now, to minimise the havoc. It is accelerating toward us now. Via Bunbury?

    I designed my 27 kW off-grid array for 9 kW in winter, but 24 kW of inverters allow generous consumption in sunny weather. One EV, welder, machine tools, water pumps, and HWS use up to 38 kWh/day so far. Add an EV tractor, and it can be over 50 kWh on a good day – all fossil free and therefore planet saving.

    On wednesday another three big water tanks arrive, raising domestic water storage to 200,000 L – making long hot winter showers a free envirionmentally beneficial luxury, as the delayed slow grey water release feeds greater plant growth and diversity in the garden. (And my cabbages.) It’s dry here now, and even the date palms need watering.

    My recent owner-build had to have 6 stars, so no need for aircon yet, but if needed, it’ll be 100% photon powered, thus net zero in all operational regards – and free in every respect, once industry becomes non-fossil and goods are photon-produced. 2050 is ostensibly the deadline for the last of them.

    With 46 kWh of battery, there’s been no generator run since installation, so zero dinosaur smoke for daily household operation and transport. That puts me where the world needs to reach, but won’t without millions of deaths, hundreds of millions of refugees, and much breast beating and wailing.
    (‘n a lot of dead coral)

    Better a $billion for faster power line construction, than for making solar panels here – unless we thereby replace Chinese coal powered efforts with photon-produced photon catchers. Maximising photon consumption _is_ the solution – if done NOW! Celebrate that the fusion energy problem was solved by solar.

    • Great stuff – pity can’t share the excess to the grid 😕.

      I believe system needs to be oversized to allow for the system to repay the debt of the energy it took to make the panels AND build the house.
      That means it needs to be quite large, made worse by the STC scheme whereby the emissions savings (not to be confused with bill savings) dont start for another 6 years as we sold the STCs (the emissions tally) to someone else and they are claiming to be green with them – can’t count it twice!

      Hence next 6 years still accumulating emissions at a household level, that means you need to pay those back after the 1 year it took to repay the emissions it took to make the system in the first instance.

      Let’s math that out for me
      27kW solar system 28MWh/year
      House use 15MWh (including 2 EVs)
      Next 7 years accumulate 7×15 MWh
      105MWh
      Don’t generate that in a year only 28 but still using 15 so can only repay 13 of the debt
      Thus another 8 years before break even.
      1 year energy payback panels
      6years renewable credits sold elsewhere
      8years payback for the emissions accumulated over the first 6 years

      Gives 15 years – gives 5 years to cover the emissions of the building they sit on…..

      Rip it off and start again 20 years perhaps – better tech more generation capacity no longer viable cleaning troubleshooting etc etc

      • Erik Christiansen says

        Karl wrote: “we sold the STCs (the emissions tally) to someone else”

        Oh! I hadn’t looked at it like that. And on reflection, I’d counter with these perspectives:

        a) Better that our real emission reductions be subsidised by penalising emitters, as we thereby contribute to motivating them to follow our example.
        In this hiatus before we go onto a “war footing” expenditure level to try to ameliorate the accelerating rate of destruction and land loss, our cost to polluters may achieve much more than our own reductions, which by themselves are not enough to save our way of life. The planet can cruise blithely on without us, so we’re not saving it. (Current $1T global transition expenditure needs to be $5T to come down from +3.4 degC, accounting shows.)

        b) My 2 sq. km of native forest absorbs more than my $8k STC offset anyway, I figure. By your accounting is that also nullified by the fact that the government stole those credits during the Kyoto Accord, passing them on to corporate polluters without recompense to landholders? If the polluters had to pay 2/3 of my rates (over $7k pa), then they’d contribute to my maintenance of a useful carbon sink, and be further motivated to stop peeing in the bilge of a sinking boat.

        It is impressive that even while ignoring the major contribution of the polluter penalty, your pessimistic accounting shows at least a 25% CO₂ credit over the array lifetime. That’s sustainable! When industry catches up, that can _reduce_ atmospheric CO₂, not just delay global nadir.

        It would probably cost over $250k to extend the grid to here for feed-in. But one could put a couple of MW of ground-mount solar in a back paddock to make that worthwhile. With grid-scale batteries as well, for more dispatchable energy, it’d be a good use for some scrubby low-yield paddocks. If that could be a small step toward Bairnsdale not needing its remote area gas peaker plant, then I’d like to see it happen. (A bit beyond my budget, though.)

  9. Bill Currie says

    Our first solar system in 2011 was 1.5kw, then 6.6kw in 2021 then 12.2 in 2023, when we added a 19.2kwh battery, changed gas cooker to induction and gas hot water to heat pump. We now have a Tesla 3. Our power bills are tiny and our spending on petrol is almost nothing (second car). Zero gas bills. I reckon we are saving about $4000 plus per year and have small CO2 emissions. We’ve also worked on draught reduction etc.
    Our electricity consumption has certainly increased substantially in the last two years but there has been a very significant decrease in our consumption of petrol and gas. So that’s not nothing. Any analysis of increased electricity consumption must take those aspects into consideration.

    • Erik Christiansen says

      Bill,

      It seems to me that your transition from direct fossil fuel consumption is the way to go. Even if your increased electricity consumption is partially grid sourced, that will probably be near-as-dammit fossil-free by 2030 in Australia, moving that too from the “problem” column to the “solution” square.

      And _any_ amount of useful renewably self-generated energy consumption is dinosaur smoke avoidance – which is a thousand times nobler than all the harmful industry and government favoured CO₂ pollution callously emitted even now, 128 years after the problem was known.

      What could really help is container-sized neighbourhood batteries plonked everywhere. Then excess rooftop energy would be available in morning and evening peaks. Significant funding could come from avoided transmission line upgrades, which are partially wasted expenditure, as current above-ground efforts will have to go underground in two or three decades anyway, as new categories of cyclone strength have to be invented. (Bunbury is but a harbinger of future high-energy atmospheric events with increasing frequency.) Distributed generation with distributed storage will become an essential element of comfortably surviving episodic grid fragmentation as main feeders go down.

      I will grant that modest energy consumption becomes important in that scarcity scenario. But the metric remains the same: If you don’t produce it, then it’s not yours to dispose of entirely at your discretion. And if there’s (micro)grid for it, then sharing surplus is optimal on all levels.

      I’ve wondered if a container of recycled EV batteries could become cheap enough that I could viably set up an EV charging station, here half way between Sale and Bairnsdale. It’d need more solar, and probably never pay for itself, but it would be a way to export renewable energy – and cut fossil fuel emissions. There’s bound to be a council regulation preventing it.

  10. Don Firth says

    Kim, in the top graph of this article there is an obvious linear shift in capacity size to about 6Kv around 2017 but then an obvious reduction of around 2Kw between Dec and Jan each year.
    Can you enlighten us as to the cause please?

    • Kim Wainwright says

      Don, my guess is that people scramble at the end of the year (Dec) so they can get in before the STCs value reduces in the new year. Then in January everyone else kicks themselves for not getting in earlier. Also, most industries typically slow down in January during the holiday period.

      • Erik Christiansen says

        The causes may be varied, but could an ingredient be “Let’s give ourselves a Christmas present” in December, followed by “Have you seen the credit card balance?” in January?

        But hold on, there’s a smaller EOFY drop as well. As this is array size, not take-up rate, I’m at a loss on that one – unless doing the tax return is a particularly sobering fiscal experience?

        That it broadly continues to climb linearly, despite increasing mortgage stress, has to indicate that the bigger arrays are providing (perceived) value, else it wouldn’t happen, I figure. (I can’t help wondering if capital city outer suburban EV uptake, for cheaper commuting, will steepen the gradient, as fossil fuel replacement has to improve payback.)

  11. Mickey Chan says

    The energy monitoring system came with the solar and battery installation. We did not know what our household consumption and how much it costed. It changes when we can look at the consumption in real time, become aware where the wastage can be cut. While not giving up the creatures comfort, there ain’t solar rebound for us.

    • Anthony Bennett says

      Hi Mickey,

      Knowledge is power and monitoring is a no brainer isn’t it.

      Thanks for the first hand feedback

  12. It’s a great discussion to have. Although, a little hard for most to navigate.

    Can we get some easy to read consumption meters that are hard-wired into a main room such as the kitchen?
    It’s all good and well to talk about energy usage. Try explaining it to an average person such as my better half. (Someone who’s no dummy and helps get the Conversation articles out there).

    I’m the only person in my household who understands energy usage and can be bothered using the app.
    IMHO, fix this and most people will start to get the picture.

  13. Marianne says

    I’m with Kim, no reason to use more electricity if there’s no need for it.
    In my former house, in Canberra, where I also installed solar, I had wall to wall carpet, I also paid for installing insulation in the roof and walls and installing double glazing. My windows also had sheer curtains, heavy blocking curtains and outside awnings. The bathroom window had no awning but Swiss blinds.
    The biggest expense was the double glazing, which had as redeeming quality that they kept out traffic noise and my neighbour’s dog noise.
    I’m now 7 years in a Qld retirement unit and also installed solar. This unit does have insulation in the roof, but not in the walls, and I’m not installing double glazing here as the window type would make that much too expensive.
    The solar capacity is smaller than what I had in ACT, but the unit is smaller and climate is much milder here. My usage is usually less than what I generate, so every year I get money from the electric company. That was the case in ACT, and in Qld also, except for one year when I did not use less than my solar generated, which was the year where the entire month of February it rained excessively. I was not flooded, but there was no sunshine for a month. And not that much in following weeks either.

  14. Solar Rebound=Jevons Paradox.
    You only have to look at the caravan industry to see the escalation in power use,mainly due to better technology and gen y obsession with having evrrything!

  15. Lyle Essery says

    I don’t think anyone is a villain for increasing energy use if they are using the energy they have produced with renewables.
    We used to try and do everything local due to high prices of diesel for my light truck. Now we have an EV , charging off the home’s solar it every where and any where . Last weekend we went the tin ca bay and back for a day trip 400kms return. Im totally not sad about not exporting the energy use to charge the EV to the grid.

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2. Put down your weapons.
3. Assume positive intention.
4. If you are in the solar industry - try to get to the truth, not the sale.
5. Please stay on topic.

Please solve: 10 + 9 

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