Your grid voltage should average 230V. But it probably doesn’t.
This time last week I was at the 2019 All Energy Conference and Exhibition in Melbourne. Or — if I have been lazy getting this article out — it was this time last week plus or minus one day. Mostly plus.
I attended a group presentation on grid over voltage. It’s a growing problem. When grid voltage rises too high, rooftop solar either reduces output or shuts down. This not only costs solar households money but costs the country lives, as clean solar energy going to waste means more fossil fuel is burned, resulting in more pollution and environmental damage.
While they do harbor a few complete grumps, the Distributed Network Service Providers (DNSPs)1 that manage local grids do actually want to increase the amount of rooftop solar energy their grids can accept. The current levels of PV penetration wouldn’t be possible if they didn’t. But the broken incentive system means there is too little emphasis on minimising losses from rooftop solar power systems.
What Is Grid Over Voltage?
Grid over voltage occurs when the voltage in the power lines your home or business is connected to exceeds the Australian standard, which is 235 volts plus or minus 8%…
Wait a minute… I think I can hear Finn screaming at me from the future when he edits this. I’d better jump forwards in time and check what the problem is…
Are you sure? Really? But that’s just nuts! Well, okay, I’ll tell them…
It turns out Australia’s standard isn’t 235 volts plus or minus 8%. It’s actually 230 volts +10% or -6%, giving a range of 216.2 to 253 volts. You may be wondering why the plus goes all the way up to 10% and the minus only goes down to 6%. Well, that’s because Australia2 really wanted to be able to say we had changed from our old standard of 240 volts down to the much more common 230 volts that is an international standard.3
The downside is it’s really difficult for a grid designed for an average of 240 volts to get down to an average of 230. We only had two sensible options:
1. Do the hard work and spend the large amount of money required to make the change.
2. Admit there would be a long transition period where the voltage would average between 230 and 240 volts.
So, of course, we instead decided to:
3. Half arse it.
We lowered the average voltage as far as it would easily go with existing grid infrastructure and then claimed to have met the standard by abusing the concept of plus or minus and allowing a big plus 10% with a considerably smaller minus 6%.
We’ve been slowly working our way down further as old equipment is replaced. At the current rate, in South Australia, this process will take around 250 years. Mind you, we’ll have to pick up the pace at some point when aging equipment starts falling apart.
Being stuck with a grid that was built for 240 volts and then using up most of the flexibility in the system to get the average halfway down to 230 volts is a major reason why grid over voltage is such a problem. There’s not much “give” left in the current hardware to easily allow voltages to be lowered further.
This is rarely mentioned in discussions of grid over voltage and wasn’t specifically brought up at the presentation. Possibly because the speakers were all so young and the decision to move towards changing the standard is ancient history to them.4
Grid Over Voltage Shuts Down Solar
Electricity flows from higher voltage to lower voltage. This means if the grid voltage is higher than the voltage produced by rooftop solar, that solar power system will be unable to export energy. While solar inverters could be designed to always beat the grid on voltage, this would be very naughty because it would push the local voltage higher and could cause electrical devices throughout the neighborhood to start smoking.
A smoking electrical device.
To prevent a bad situation getting worse, solar inverters will shut down once grid voltage reaches a set limit. Usually, older inverters have higher set points while most modern ones can reduce their output gradually as grid voltage rises.
What To Do If Grid Over Voltage Shuts Down Your Inverter
South Australia Power Networks get over 10 complaints a day about grid over voltage. In August, Richard Chirgwin wrote about how the problem is getting worse. He reported that, according to Solar Analytics, 50% of their customers had their solar energy reduced or shut down at least 50 times a year. That’s an average of about one or more times a week, although these events will be less common in winter when solar output is lower. For solar homes in particularly bad locations, grid over voltage can easily cost them hundreds of dollars annually in lost generation for an average sized system.
Fortunately, there are things you can do. The DNSP in charge of your local grid has a statutory obligation to prevent over voltage. That’s a fancy way of saying if there is a problem they have to fix it. While it may not be reasonable to expect the grid to always get it right, if lost solar electricity production ever becomes more than a mild inconvenience thanks to grid over voltage, it should be fixed.
But an over-voltage error on your solar inverter may not be your DNSP’s fault. It could be caused by your solar installation or your existing grid connection. Specifically the wires from your inverter and switchboard through to your grid connection point may have too high a resistance. This can be caused by distance, thin wires or bad connections. Your installer should check your home’s voltage rise before installing but, unfortunately, many do not.
How To Diagnose The Cause, Then Fix It.
So how do you determine if your voltage rise issue is caused by your installation, your grid connection or your DNSP?
Finn has written step by step instructions on how to diagnose the cause and what to do about it. If you have a grid over voltage problem, ask your installer to follow those instructions step-by-step5.
4 Speakers +25% / -0%
There were 4 speakers plus 25% minus 0%. Actually, it would be clearer to explain there were 3 individual speakers and one presentation by a duo baritone and soprano. They were, in order:
- James Sturch: Technical Director for Sonnen Batteries in Australia and NZ. Sonnen has a factory operating in Adelaide where they assemble battery systems.
- Travis Kauschke: Senior Engineer at South Australia Power Networks.
- Tom Langstaff from Ausnet and Claire Cass from CitiPower/Powercor. Both from Victoria.
- Candice Horig: Distribution Standards Network Officer for Energy Queensland.
I’ll go over the main points raised but not worry about the details of exactly who said what, as it is ideas that are important, not people.6
Solutions for grid over voltage covered three main areas:
- Changes to solar inverters and their settings.
- Upgrades to the grid.
- Changing electricity consumption patterns.
Changes To Solar Inverters & Settings
One of the presenters — I won’t bother going into who, but his name rhymes with this guy’s…
…was concerned about solar inverters that shut down or reduce output at a higher voltage than the area’s Distributed Network Service Provider mandates. This could be because some are older systems installed when voltage limits were higher and which are excused from current requirements. But sometimes — or with some installers often times — when a household complains to them about grid over voltage events shutting down their solar power system, they will adjust the voltage limits on the inverter upwards.
This is a bad thing to do without written permission from the local DNSP because it can make things worse for every other solar household in the nearby area by making their solar systems suffer from more grid over voltage events. Also, everyone in the street, whether they have solar panels or not, can end up using more electricity than they intend or need to and can have the lives of their electrical devices shortened thanks to the increased grid voltage.
This is unfair to solar installers who follow the rules, as it can cause their customers to start complaining to them about grid over voltage.
One suggested way to get around this problem is to stop DNSPs from setting their own inverter limits and getting them to agree on one for the whole of Australia. This way all the inverters sold here could just have one setting out of the box and it wouldn’t be possible to change it. The disadvantage is, unless there is some way to unlock the inverters, it won’t be possible to change the settings when it would be beneficial to do so. But, from a grid management point of view, the benefits would outweigh the loss of flexibility.
We’re not going to have an Australian-wide inverter standard in the short term because there was an attempt to get the DNSPs to all agree and it failed. But Victoria and Queensland are moving towards standardized statewide settings.
On this sustained over voltage setting, Queensland’s twin Kingdoms of Ergon and Energex shall unite!
Flexible Modern Inverters Allow More Solar Power
Modern solar inverters sold in Australia are generally able to adjust the type of power they output and gradually reduce power output as grid voltage rises. I won’t go into the details of these features that are known as volt-var and volt-watt…
Unless you already know what they are, these explanations are of no use at all.
…here7, but this flexibility is so useful for allowing more solar power on the grid we were told if all inverters had these features the amount of rooftop solar could be doubled without making grid over voltage worse than it is now.
As a result, one suggestion is to replace older inflexible inverters with modern ones. This sounds like a good idea, provided it’s done fairly and voluntarily. Also, no matter what amount of incentive is offered, people should be free to use it to get a modern inverter or put it towards scrapping their current system and getting an entirely new one. Paying good money to put a new inverter on a system with crap, deteriorating panels is pretty dumb.
Technical Note From Finn:
Many DNSPs are now mandating Volt-Var and Volt-Watt capable inverters
The Australian Standard that defines grid connected solar inverter requirements for Australia, AS4777.2:2015, says this about volt-var and volt-watt modes on inverters (clause 6.3.1):
The inverter may have the capability of operating in modes which will [allow volt-var and volt-watt response]…
The ‘may’ means it is optional – according to the standard.
However many DNSPs are moving to make it compulsory to use both a voltage-quality capable inverter and enable the modes with specific settings.
Here’s a handy list so you know what is being mandated and when.
- All Victorian DNSPs (CitiPower, Powercor, Jemena, AusNet, United Energy) will mandate Volt-Var and Volt-Watt from 1 December 2019
- All Queensland DNSPs (Ergon & Energex) will mandate Volt-Var and Volt-Watt from 1 December 2019
- In South Australia. SAPN has already mandated Volt-Var and Volt-Watt modes.
- Western Power in WA mandated Volt-Var and Volt-Watt on the 1st November 2019.
Upgrading The Grid
One simple way to decrease grid over voltage problems is to replace existing power lines with fatter ones as thicker cables contribute less to voltage rise8. This includes street power lines as well as those from the street to the switchboards of homes and businesses. Unfortunately, like many things that are worthwhile in life (such as chocolate), this costs money.
Another way to improve the situation is to adjust the voltage of existing street transformers. The drawback is, a vast number can’t have their voltage lowered any further. As I mentioned, changing from the old 240 volt standard towards our aspirational target of 230 volts consumed a lot of the existing flexibility in the system. These old street transformers can be replaced with ones that can be adjusted lower or, better yet, replaced with ones that are quite happy to adjust themselves, but again this will be a considerable expense. Personally I think would often be worthwhile if all costs were correctly accounted for.
Changing Consumption Patterns — Controlled Loads
Queensland can turn controlled loads, such as off-peak hot water systems and other devices, on or off by sending signals through the grid9. They have actively used this for years to reduce the likelihood of grid over voltage events. While these controlled loads used to only be turned on at night to help coal power stations continue operating, they can now be switched on whenever it will help support the the grid.
South Australia is another state with a lot of controlled load hot water and they are trialing a similar approach, but their controlled load system is a lot dumber than Queensland’s, so it will be a long time before it’s as flexible.
Changing Consumption Patterns — Prices
When done right, changing the way people are charged for electricity can be an effective way to get consumers — especially businesses — to change their electricity consumption patterns and help reduce the likelihood of grid over voltage occurring by shifting consumption to the middle of the day, or better yet, to exactly when it gives the most benefit. But when done badly, such as when people are forced onto plans they don’t want or understand, it’s a great way to make everyone hate you.
One example of a price incentive is South Australia’s introduction of a “solar sponge” tariff where electricity is cheaper in the middle of the day. This is only relevant to people who have smart meters, which is still a small percentage in that state, but it is an incentive that will help reduce grid over voltage, even though the effect will be small at the moment.
Changing Consumption Patterns — Free Stuff!
Another way to change people’s consumption habits is to give them free stuff, such as smart home energy management systems, that will alter their electricity consumption in ways that assist the grid. None of the the speakers actually mentioned this approach, but I did make a point of telepathically broadcasting it to the crowd, so I think it’s fair to bring it up.
Personally, I don’t know why why DNSPs aren’t handing out slow cookers to all who want one in areas with serious grid over voltage issues. They slowly consume energy during the day and reduces the amount needed for cooking in the evening — which is another problem the grid has to deal with.10
The Grid’s Deadly Incentive Structure
One thing not mentioned by any of the speakers, which is at the heart of the grid over voltage problem, is the incentives that our grid currently operates under are, stochastically11 speaking at least, fatal.
This is because fossil fuel generators are not required to pay the health costs of the pollution they create and don’t pay for the environmental damage they cause. If they did have to pay for these externalities then every time grid over voltage reduced the generation of clean solar energy by one kilowatt-hour and increased coal generation by roughly the same amount, then overall the grid would be likely to lose at least 8 cents12. Under these circumstances you can be certain they would bend over backwards to prevent the loss of clean solar generation from grid over voltage and we would also see extremely rapid expansion of renewable energy.
Footnotes
- DNSPs take power from high voltage long distance transmission lines and distribute it to homes and businesses. They are responsible for ensuring grid voltages don’t exceed the relevant standard. ↩
- Western Australia is the only state that’s still dragging its heels on this. ↩
- The only countries with voltages much lower than this are Japan, Brazil, and a handful of unimportant countries such as that weird one Boris Trump is President of. ↩
- None of them had beards nearly as long as mine. Especially the women. ↩
- And yes, you have to follow it step-by-step, if the installer misses out a step it defeats the whole point of the procedure, which is to carefully establish the cause of the over voltage so it can be fixed ↩
- Or at least it seems that way up until you meet someone with an ideology and a gun. ↩
- Not understanding what the terms mean is not the reason why I’m not going into detail here. It’s only one of several reasons why I’m not going into detail. ↩
- Alternatively, instead of making power lines thicker, aluminium ones could be replaced with more conductive copper and copper ones could be replaced with gold or silver. But this would be extremely expensive. You’d have to buy protective gear for all your werewolf line workers. ↩
- The signal is called a ripple and sometimes makes lights flicker. On rare occasions this has induced fits, but not nearly as many as opening electricity bills have. ↩
- Note: This is not an attempt by me to get a free slow cooker from a DNSP. It’s an attempt to get me and a whole heap of other people free slow cookers. ↩
- They’re not trying to kill anyone in particular. They’re not trying to kill anyone at all. But the system will result in people dying. ↩
- A low estimate of the health cost of coal pollution is a minimum of 1 cent per kilowatt-hour and 7 cents ($70 a tonne) is a low estimate for the cost of removing CO2 from the atmosphere and sequestering it. ↩
About Ronald Brakels
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Excellent article.
Suggest article on solar and grid synchronicity would be of interest to many.
We’ve only touched on it now and then, as far as I remember, so a dedicated article on that is definitely something I could do in the future.
Hi Ronald.
Ok, brace yourself for an outrageously stupid question…
Say my system is shutting down due to oversupply. Would using more electricity in my home during these shutdowns help? ie Would my system perform better because that energy is being immediately ‘used up’ in my home? Or is the connection to the grid such that the oversupply issue remains anyway and will continue to impact my system, regardless?
I fear the latter, but am curious and blindly hopeful…
Thanks 🙂
You’re correct, increasing your daytime load will help to reduce overvoltage issues at your house.
The voltage your inverter sees depends on the amount of power that your solar system is generating, your household load, and the amount of power that other solar houses near you are sending back to the grid. You can’t change the voltage rise caused by other houses, but you can certainly reduce your own.
Voltage rise caused by your own solar system occurs over two wires: a wire running from the inverter to your main switchboard, and your consumer mains (a wire running from your main switchboard to the grid connection point). You can see a diagram of this connection here: https://www.solarquotes.com.au/blog/wp-content/uploads/2014/12/voltage-rise-rules-nsw.gif
When your solar system is generating, total voltage change from your inverter to the grid-connection point is the sum of the change across those two wires. Voltage rise across a wire depends on the length and diameter of the wire, as well as the amount of power flowing through it.
Regardless of your household load, all power generated from your solar system will go from your inverter to your switchboard. That means that as long as your solar system is generating, you’ll have a voltage rise across that wire.
Power will then flow from your switchboard to your house, taking care of internal load. Any excess power will then be exported to the grid via your consumer mains, incurring a voltage rise across that conductor. Again, voltage rise here depends on the amount of power exported, as well as the wire itself. Increasing your household load means less power exported across your consumer mains, and hence less voltage rise.
Simple things like running your dishwasher/washing machine during the day can help. If you have a pool pump, or an electric hot water system, you can get a timing relay installed that allows you to set what time you want it to turn on. This is an easy way to shift these into the daytime and maximise the benefits from your solar system.
As Says said, it will help. Of course, there are limits to what your home can achieve on its own.
It’s easy to imagine a future where solar inverters will your home energy management system that voltages are rising and it would help to switch some appliances on. If you were charged less for grid electricity that would also be a big help. If you had a large load like an electric car — around 23 kilowatts with a 3 phase charger — it could help a hell of a lot by switching on at the right times.
is a such a problem => is such a problem
to smart smoking => to start smoking
Thanks! Fixed now!
(Remember kids, it’s never smart to start smoking!)
Ronald,
on my new system I did 2 things: faced half the panels West, using Optimisers, & set the inverter to Voltage control. I was lucky in that my old system was 2 phase, 5Kw ABB on each phase, so I was able to fit new Solar Edge inverters on my new 14Kw modest system (generated 85 Kw/day over summer on a clear day!). My inverter runs voltage control, so now never drops out. Once the neighbors systems ramp down, mine ranps up to 10Kw export total.
Soon to fit a battery system (a heart choice, not an economic one!)
btw, the
all-energy conference was great! Well worth the trip down.
regards, Doug
Interesting stuff. Could you maybe expand it with the effect of more batteries and smart meters entering the grid?
Definitely something we will write more on in the future. As long as incentives are right batteries and (not really that) smart meters will have a huge effect. Today’s electric cars all tend to be connected to the internet so it would not be difficult to have the ones that are plugged in draw power when ever it would help support the grid.
I’ve written on your forums previously about this.
We’re in NSW in an Ausgrid area and we had problems from day one after installing an 8.7 kW system. Whilst I tried to anticipate this and argued with the system provider (before installation) to use a 3 phase inverter I was told I didn’t know what I was talking about that we only needed a single phase inverter.
We battled along for almost 12 months and nobody wanted to fix the over voltage issue despite the inverter cutting out up to 20 times a day.
Eventually I tired of the BS and asked the installer to remove the system under threat of Fair Trading. He responded by agreeing to replace the inverter with the 3 PHASE INVERTER I had always insisted on.
After a long period of denial Ausgrid also lowered the street voltage by 10 volts (from memory) and the 260V spikes then came down to around 240V and the system has worked like a charm ever since.
To readers I say be insistent and certainly consider the 3 phase option as this makes a significant difference. Ronald has it right about street voltage but this is constrained as the house at the end of the loop has to have a usable product so sometimes there’s not a lot which may be able to be done. Of course the real problem is our coal directed government which has not addressed this issue and will likely continue to give it lip service rather than fixing it.
On a wider note it may not be pertinent to upgrade the wiring in the entire system as when (real) battery storage arrives and energy is no longer exported what we have may suffice. That of course requires a crystal ball and making a call which may be wrong in the context of time. Until then we’ll all need to adapt as the goal posts move. We did and now product a motza of power. Did 60 kWh the other day. Who needs the grid.
Agreed, be persistent: I went to the Victorian Energy Ombudsman regarding grid spiking which was common in our area for many home solar generators . The Ombudsman ordered Powercor to resolve the issue, which they did quite professionally. It should be incumbent on installers to be aware of any local issues when designing systems.
Very clear and interesting article. Thank you.
I have a Solar Edge inverter with online monitoring. Does anyone know if there is a data set available in my online monitoring that would tell me if my rooftop solar is either reducing output or shutting down because of these voltage issues?
Or should I just be looking for a lot of spikes in the daily output graph?
As Morgan Jones of”: Valve Amplifiers” fame has pointed out:- “230Volts” is just a paper ruse to satisfy EU mandarins in Brussels; it’s 240Volts, just as it always was. All they did was to adjust the tolerances so as to include 240 Volts; in my street, it’s 247 Volts, even after the sun sets, but then we are one house down from the street transformer.
When you say over voltage in the supply line shuts down solar systems does this mean the installer has to be called which will mean a call out fee to “reset” your solar system. Please explain.
Your solar inverter will shut down, but if the grid voltage returns to normal it will only be for a short time. It will regularly check the voltage and when it’s acceptable it will switch back on again.
Well, isn”t this the very essence of a good solar system, surely the grid feed-in wont be down for lengthy periods of time so no one is really going to lose a lot of “feed” into the grid, so there is not a big downside cost in dollar terms here. Isn’t that correct ?
Well, an averaged sized system could easily have their electricity bill increased by $1 per hour of shutdown with a medium sized system and a lot of people have suffered from more than 50 hours in a year. There are a lot of people who have suffered more interruption than that. Also, there is a hidden cost we don’t see where people are prohibited restricted in how much new solar systems can export to the grid or prohibited from exporting at all.
Our shut downs are fairly constant. So we lose a lot of FIT. More than half, compared to a ‘good’ day, as a crude estimate.
The discussion is very helpful. We are planning a new system, and looking at pros and cons of including a battery in the new system.
My question is “as the problem is essentially a mismatch between too much production and too little consumption, could a solution involve installing a battery system to “soak up” the excess production?”
Or having some sort of relay switching on an extra appliance, such as a pool pump, to increase consumption and reduce the excess?
I realise now that the issue has been covered in previous posts, which I had not read before posing this question. Apologies for that error.
I’m pleased to read your explanations and warnings about the effects of over- voltage, and it’s interesting to see how the various States handle the problem. How does Tasmania compare with other states?
It’s a particular challenge for us on the end of a rural power line. Here’s a couple of plots of 5-min samples of line voltage on each of our phases:
– over a month
https://i.imgur.com/LG4gsIe.png
– over a 5 day sample period in that month
https://i.imgur.com/vCBULGh.png
Easy to spot which phase the controlled load hot water is on (hint, the blob of red dots lower on the chart around midnight each day). Almost like clockwork, the controlled load hot water results in a 10V drop (or rise) when switched on (or off).
Our inverter (Fronius Symo) does a pretty good job of managing over voltage events, which as can be seen are an issue on one phase in particular. That same phase also sees lowest voltages, and a 30V swing on that phase over the course of a day is not unusual. Hence convincing the DNSP to tap it down is a bit is problematic because you can bet others further up the line are possibly experiencing some under voltage events.
You didn’t answer my question, I suppose I will have to try and get the answer from another solar boffin.
Sorry, I’ll try again.
When your inverter shuts down because of grid over voltage it will automatically turn back on again provided the voltage has fallen. There is no need to pay for someone to come out to reset it.
Still missed the mark by the proverbial mile, but I am getting used to this pathetic runaround by people in this industry. It’s a snake oil salesman’s paradise.
Sorry about that. State your question again and tomorrow I’ll get someone else to answer it.
e
I have a Solar Edge inverter with online monitoring. Does anyone know if there is a data set available in my online monitoring that would tell me if my rooftop solar is either reducing output or shutting down because of these voltage issues?
Or should I just be looking for a lot of spikes in the daily output graph?
I have an Edge IQ unit installed before my main meter which only allow 225vlts in to my house,was having trouble with Notice567 coming up on my Fronious inverter therefore shutting down for a bit and seems to have stopped it most of the time
The Australian Standard that defines grid connected solar inverter requirements for Australia, AS4777.2:2015, says this about volt-var and volt-watt modes on inverters (clause 6.3.1):
You did not mention what is happening in NSW re this Voltage problem can you advise where we stand
Hi Colin
I’m not aware of any volt-var and volt-watts requirements currently in NSW, but I’m sure they’re coming soon.
Grid Overvoltage is definitely a problem in NSW, although how much of a problem it is difficult to say. NSW has a few advantages over other states — the number of households with solar in NSW is still low compared to states like SA and QLD, there’s no Solar Homes Rebate scheme like in Victoria causing a sudden increase in new installations, and the grid is generally considered to be in a bit better nick than average. But this doesn’t mean areas can’t have serious grid overvoltage issues.
We have been having issues recently. Also no joy from the installation company either, which is very disappointing as we chose them due to company reputation. Our AC isolator keeps shutting off and needs to be switched back on? What causes this I am unsure? It is the switch/breaker from the inverter back to the grid? Who should we be contacting to get the sorted out? Thanks
Hi Gary
It sounds like you have a faulty AC isolator or possibly an undersized circuit breaker. If the solar installer won’t come out and fix it you may need to contact the consumer affairs office in your state and get some advice from them on how to proceed.
Hi Ronald
I’m sure insisting that all inverters are set up with common voltage limits will help a little with over-voltage issues – but I don’t think this will result in a fair and equitable arrangement in the short-term, nor solve anything much in the long-term as PV penetration increases.
My inverter certainly uses a volt-watt configuration, possibly also volt-var but I’m not sure. Both are now mandated in WA for new installations.
The reason I say this will not result in a fair and equitable result, is that our individual result depends very much on our whereabouts on the line we are connected – consumers on the end-of-the-line are invariably going to be the first to have their feed-in tariff curtailed when distributed generation is high and demand is low (e.g. either side of the lunch time peak demand) – simply due to the “negative voltage slope” in the line. So, while installations near the transformer may still be able to export maximum power, those at the end of the line will be export-limited first – simply because the voltage is higher there.
This problem will only get worse with increased rooftop PV-penetration (and also with increased infill, if voltage tappings must be increased to prevent excessivley low voltages during periods of high demand and low generation).
As you say, the only options may be to have control over demand and inverter outputs, or increase the thickness of the grid wiring (highly disruptive in mature “bedroom” suburbs).
To me – all these required fixes are simply the “cost of going to renewables”.
Not that I’m saying we shouldn’t – just that these costs act to increase the true cost of renewables – as does battery storage – we should be thinking “big picture”.
Can all the roof top solar system work together if they are all competing to put power into the grid.
I would think that all the inverters are really 230 volt units – some can be increased by programming. Europe and China are 220-230volt. All of Australia voltage but for parts of WA is 240volts, parts of WA was as high as 250volts. For Australia to change to 230volts is near impossible. Australia went to this voltage due to the long distance of power lines is in the country areas. Voltage drop is a problem.
Generation voltage must be higher than the grid voltage to have current run into the grid. Large power station have controls of frequency and voltage. Small wind and Solar controllers don’t always work. So if there are a lot of wind or solar generators the voltage could be high. So much for this article wanting to drop our voltage to 230 volts.
My voltage is 249 volts with solar and no solar 247 volts. So much for their 230 volts. With all the small wind and solar the 230-235 volts is a dream, will not happen. Renewable could end up becoming a large problem.
I think you hit the nail on the head, Nick.
My inverter is a fairly recent model SMA 3-phase – it starts throttling the power back, when it senses an output voltage on ANY phase, exceeding about 250 V as best I recall, with the output limit steadily decreasing to zero as the detected grid voltage reaches about 255 V (figures were read from a download, but I can’t find them now, may be a bit “rubbery”, but the general principles apply).
As far as I am aware (I had Synergy come out to measure the high grid voltages), at maximum output the voltage loss across our feed-in line was about 0.7 V – so not so significant in the overall scheme of things.
The point is – we have a commercial site not too far and upstream of us, and the reduction of our feed-in potential reduced significantly as this came online.
I think the problem is, that when a whole host of inverters feed into the grid when the demand is low, the voltage “at-the-end-of-the-line” increases enough to prevent the more remote inverters from being able to share in feed-in – the system is non-equitable. And this is true, even if all inverters were to be standardised as Ronald has suggested would help. After a point, neither can the DNSP’s lower the transformer voltage tapping further to prevent the excessive voltage rise, as then the “end-of-the-line” will go too under-voltage when PV generation ceases at the end of the day, and demand grows.
You can’t have your cake, and eat it as well.
Although I agree standardising inverters will help somewhat, in the limit as more PV penetration occurs we MUST see even more voltage rise issues.
The only solutions I can see, are to either increase the size of the grid wiring cross-section (expensive, and highly disruptive I’d think), or insist that owners install batteries and store the excess energy there for use in the high demand period (but this will only work while there is not too much PV).
I’m for renewables, but this is a case of a non-transparent cost needed to go that way.
We have to be realistic – if we want renewables, we have to be prepared to pay for them.
I have installed a unit from Edge Electrons which is mounted before the power box and it only allows 225vlts into the house,i had the 567 problem on my Fronious before of over voltage but now it does not happen as much,any comment anyone?
I am not a sparky so forgive a stupid question, would it help if all solar systems had a battery attached, I am not saying they should, just asking if a battery would hrlp the problem?
You might think so but not really.
Most home batteries are a dumb load, by that I mean they are not readily programmable as to *when* they charge nor how quickly they charge.
As a result they are often not helping when it’s most needed since on days when grid over voltage is most common (i.e. mild weather, sunny days), batteries are typically fully charged by mid-morning and so the household solar PV is still cranking out exports to the max in the middle of the day.
Indeed people often lament their battery gets full before their solar PV system hits export limits, when it would have been better for the battery charging to be delayed to soak up the otherwise unrealised capacity of the solar PV.
Some people hack their Powerwalls or other battery systems to enable more control but these are not user friendly options.
That would help as residential grid electricity use would be much lower in the late afternoon and evening. Overvoltage issues mostly occur because voltages are set to meet air conditioner demand in summer at these times.
Hi Darryl
I had a look at their website – but there is no description of how the unit works (technically).
Though, their statement that you can increase your harvest of solar power using it – even with excessively high grid voltages – looks a bit worrying to me.
This would suggest it converts the 225 volts that your house is set to and presumeably what the Solar inverter would generate, up to whatever the grid voltage is, even boosting that voltage to enable the inverter to avoid throttling.
This would seem illegal to me – it’s a bit like connecting a voltage-reducing auto-transformer between the grid and your house – which will act as a voltage booster when exporting solar excess – causing uncontrolled large voltage rise in the grid that the DNSP’s might not be too happy about. Nor all your neighbours.
Thank you for your answer which worries me a bit to think it is illegal for what they have put on my system,i will wait and see what my next bill or credit is, the people who suggested i put it was called Energy Stuff if you wanted to contact them,Jemena power came out before and measured the power coming into the house and said it was ok up to 247vlts which was causing inverter to show 567 and shutting down but when the unit was put on it stopped,tell me what is illegal about it it may pull it off
Hi Darryl
Well, I can’t be sure about how the device works – but from your comments it is apparent the your inverter was shutting down or throttling at 247 volts previously (your error code would say) and now doesn’t due to the house voltage being stepped down.
The only way the inverter can export then if the adaptor unit maintains the house voltage at 225 volts, is for the unit to force the extra power somewhere else – and the only place it can go to is into the grid – and the only way that can happen is for the voltage at the output of the adaptor unit to go greater than 247 volts (or what ever the grid gets to) – so the extra power can be shipped out.
All network operators are required to limit the maximum voltage anywhere on the grid – in WA for example, we are limited to 240V + 6% = 254.4V – and this is by law. All inverters are set to limit their maximum output voltage, also by law in order to be allowed to connect to the grid – but if your adaptor unit boosts or removes this limit, then it would be in breach of the law – in fact if this is the case and it is detected your DNSP would demand you remove the device.
Another side of this, is that neighbouring PV systems may have their feed-in tariff reduced or curtailed, as your device “hogs” the grid.
Maybe someone else has more knowledge about your device – it is possible it retains the voltage shutdown/throttling limitations – although this would mean their promise of more solar harvest could be a bit misleading.
Just doesn’t seem right – something is “off”…
Thank you very much for your info Ian i will get in touch with these people and tell them what you said
I’d be interested in what you find out.
Maybe they DO take care to prevent excessive grid-side voltages – you’d hope so.
But then, if you are already near the maximum allowable grid voltage in your location, it does beg the question of how your harvest of more solar energy could occur.
This is a valuable discussion – thanks to everyone for their helpful comments. Helped a great deal in selecting an integrated air conditioning plus a solar system.
Have just ordered a system using Configuration #7 in Finn’s article, 10.5 kw LG panels, Solaredge inverter, Powerwall 2 with 16 kw Panasonic single phase air conditioner.
We have a lot of blackouts in our leafy suburb, with storms causing trees to fall on power lines. So ability to function in a blackout essential.
Found it challenging to find solar firms and air conditioning companies who were tech savvy enough plus interested enough to get Involved in the project.
Solar Quotes referred an excellent firm to me, so everything is working as intended – thank you.
Question from America. My grid power is 107VAC(should be at least 110) when I plug my solar generator into the gird my lights dim and fans slow. It seems like plugging into the gird bypasses my solar generator in favor of the gird. Unplugging from the gird also tends to put my inverter into protection mode. The lights and fans brighten up when I do but often the 120VAC outlets fail, if I completely disconnect the solar generator it resets after a bit of time. Any idea what my problem is? Is my gird causing these issues? Is the design of my solar generator sub-par? The manufacturer is trying to replicate the issue but with no luck so far.
I’m afraid your situation is so different from a typical solar installation in Australia I can’t even make a guess, Donald.
Interesting to note recently for SA on 14 March 21, first controlled reduction of home PV by SAPN:
https://wattclarity.com.au/articles/2021/03/14march-heywoodrepair-lowdemandsa/
and
https://reneweconomy.com.au/switching-off-rooftop-solar-will-become-a-regular-feature-of-a-renewables-grid/
hi Ronald,
I have just had solar installed and am noticing frequent grid overvoltage faults.
What I don’t understand is, why doesn’t the battery or PV supply the house, rather than the house drawing off the grid?
Is there something I can do to change this?
cheers,
Rob
Katherine, NT
Single phase Sungrow SH5K-40 hybrid inverter
LG Chem Resu (48V) – 10 LV – 9.8 KWh
Hi Rob
The first step is to inform Power and Water about the over voltage problem. They have a responsibility to keep the voltage within the mandated limits so hopefully they will fix the problem quickly. Unfortunately, these issues aren’t always fixed quickly.
During over voltage events your solar and battery system will only be able to operate if your home is taken off-grid. This has the disadvantage that you may be using, or want to use, more power than your solar and battery system can provide. If you think you want to try this anyway you can check with your installer on what can be done.
Many thanks Ronald.
The solar was only finished on Wednesday last week and the monitoring device activated on Friday arvo, so I was thinking it might be a fault with the set-up.
I was explicitly told in the event of the grid going down that we would still have power from the battery and the panels would still be charging the battery, so I’m surprised in this circumstance this isn’t happening, but I’ll follow up tomorrow, as well as contacting Power and Water.
Just as an aside – how can I double-check the grid voltage? Is there anything on the inverter that records this or would I need a sparky to do something? There’s a friendly one across the road who’d be happy to do it if it was something simple!
The inverter should show you the grid voltage. If you can’t find it, you may need to check the manual to see how it’s displayed. Australian grid voltage is supposed to be maintained between 230 volts +10% or -6%, giving a range of 216.2 to 253 volts. (Yes, +10% or -6% is weird.)
When there is grid overvoltage the grid isn’t down, so your home doesn’t switch to running off the solar panels and battery. Instead, because of grid requirements, your solar system and battery are required to shutdown. It’s annoying, but if the grid voltage is normally within the mandated limits it should be a rare occurrence.
I’ve searched the manual (with my limited understanding of eleccy-teccy stuff) and can’t find any mention of how to check grid voltage – though under quite a few error codes it says you should check the grid voltage!
At least now the house is being powered by the battery – there’s been quite a few times when the system was up and running that the system was pulling from the grid when the battery was close to 100%, or even charging the battery and pulling from the grid at the same time. I guess the algorithms have to bed themselves in …
Anyway, I’ll talk to my installer and Power and Water tomorrow and see what comes.
Thanks again for your responses.
https://gold-coast-solar-power-solutions.com.au/wp-content/uploads/2016/07/SH5K-User-Manual.pdf
Well, that was easy. Called Power and Water and within 30 minutes they were over, checked some voltages, agreed the grid voltage was too high and said they’d ‘tap down’ the transformer straight away! Also mentioned someone else on the street was having the same issue over the weekend.
Glad you had such an excellent result! If only Australians everywhere could rely on that kind of service.
The NT is hit and miss like that.
It could easily have been the worst experience in the world, depending on the organisation and the people.
But in this case, small town, practical techies with pride in work and not under the thumb of millions of managers, just saw the problem and went and immediately fixed it. What a relief!
Thanks again for your replies – if it hadn’t gone this well the info you passed on would have been invaluable in the battle!
Thanks for the reply
I have a question. My solar panels are have not been working for over a week. The installer are saying it’s due to low voltage but other ppl in the neighborhood with solar are not having the same problem . What could this be ?
We need a lot more details to diagnose! please send an email to [email protected] with solar company name, system details (ideally single line diagram which is part of the mandatory documentation package), and let us know what monitoring you have.