A Problem Nobody Anticipated – Excess Solar Energy

[Pommie]

South Australia went very green and demonstrated it by blowing up (yes, with explosives) a coal fired power plant. They replaced it with wind and solar. When a big storm hit, the turbines had to be shut down and solar was in the dark. Net result an overload of the inter-connectors to other states - result, total blackout. Not sure if this is the problem described in the article but sounds like it and I've not heard of another similar event. If it was, it's the opposite of what they state, not having enough standby power available.

Mike.

 

[Visitor]

A quarter of a million independent solar power producers with no means of disconnecting them from the grid (other than cutting power to the homes) that can supply more than the grid demands. That's the point of the article Nigel, as was explained in the first paragraph of my post. You might actually read the article before dismissing it out of hand.

It's not about solar farms, wind farms or spaghetti. If these producers supply more than 100% of the demand, and the utility has no means to shed that power production, the results are not good. That is the story. And that solutions are being developed.

Adoption of home grid-tied solar arrays has been wildly successful in some parts of the world. But the success has introduced other consequences. Consequences that most people don't understand.

 

[augustinetez]

The blackout mentioned in the article above was due to a huge storm causing damage to infrastructure - maybe Terry (from S.A.) will know more on this subject.

The big blackout several years ago was storm damage taking down the pylons of a major feeder, nothing to do with solar power, wind turbines or any other for of electricity generation.

The collapse led to overvoltage in the system which carried over to cascading automatic shutdowns of the network and the interstate feeder was not allowed to operate in case it caused damage to that as well.

The media just told a pack of lies about the cause, as did others who knew better.

The length of the blackout (up to two weeks in places) wouldn't have happened except for the lack of foresight and investment in base line power generation infrastructure in South Australia.

Presumably, as usual, it's just a made up newspaper story and complete nonsense - you simply shut down part of the larger producers, like the solar farms.

No, unfortunately in this case it's not a complete media make-up, they are seriously considering charging people with solar panels who feed in to the grid.

As stated in the article, we (on new installations) now have to have remote shutdown/override technology in the inverters and as for what some would think of as a simple solution (shutting down the solar farms or wind turbines) - isn't going to happen because those people have money and as we all know, those with the money make the rules.

Unfortunately, as per usual, everybody is just going to sit back and let it happen - ripped off again.

 

[tomizett]

A simple solution would be to have a max voltage that power can be fed into the grid.

Surely this is the point though? A crude over-voltage cutout, while a sensible safety precaution, seems like a naïve design decision on the part of whoever designed the GTI. It seems to be predicated on the assumption that there will always be more load on the grid than the inverter can supply. Surely it would not be too hard to taper off the power output as the line voltage exceeds its nominal value?

It's interesting to consider what might happen to the frequency and phase of a large "island" of GTIs isolated from the main grid. If the "island" drifted out of phase it would make it extremely problematic to re-connect to the grid.

A single GTI on a large grid is a (theoretically) simple proposition - as someone on this forum pointed out a while ago, it just needs to look like a negative resistance. However, it looks like we're getting to the stage where we need to start considering these devices as prime generators and thinking about how they'll interact.

 

[Nigel Goodwin]

A quarter of a million independent solar power producers with no means of disconnecting them from the grid (other than cutting power to the homes) that can supply more than the grid demands. That's the point of the article Nigel, as was explained in the first paragraph of my post. You might actually read the article before dismissing it out of hand.

Can only a quarter of a million small scale providers provide more power than the entire grid uses?, I wouldn't have thought so? - if it's producing more power than the local area is consuming (at certain times of day) why isn't it simply fed elsewhere down the grid?.

 

[Visitor]

Once again, the article explains the situation.

 

[Lo_volt]

I've had a solar array (8.5kW) here in the US for nearly 10 years. About 3 years ago, my neighbor bit onto one of the solar panel lease sales pitches and had a 13,000 kW system installed. After a few months, I realized we have an issue. We are both fed from the same transformer from the power company. On cool sunny days, when neither of us is using much load, my system goes into a "de-rating mode" due to the AC voltage going too high. I haven't looked at his inverter, but I assume it's doing the same thing. Essentially I'm losing 1-2 megawatt-hours of generation because the grid voltage goes too high on those cool sunny days!

I'm not sure why inverters wouldn't do the same thing over in Australia? Or is it that they are de-rating and not generating their expected output?

 

[Diver300]

I've had a solar array (8.5kW) here in the US for nearly 10 years. About 3 years ago, my neighbor bit onto one of the solar panel lease sales pitches and had a 13,000 kW system installed.

I guess you mean that your neighbour had a 13 kW system.

 

[augustinetez]

I'm not sure why inverters wouldn't do the same thing over in Australia? Or is it that they are de-rating and not generating their expected output?

I know for a fact that my inverter shuts down if the grid goes over voltage and slowly decreases the amount it is feeding in as the grid voltage approaches that point.

Can only a quarter of a million small scale providers provide more power than the entire grid uses?

Most definitely - as previously said the (useless) powers that be in this State blew up a power station and did nothing to replace the base line power generation capability or upgrade the power distribution system in this State to handle renewable energy generation from whatever source - they relied on interstate inter-connectors to supply power when needed previously and expected it to continue the same way. Now one of the interstate connectors has problems and they are talking billions of dollars to build another one instead of making the State self sufficient in the power generation stakes - talk about eggs and one basket.

As mentioned, the huge growth in rooftop solar in South Australia is because of the massively rip-off cost of electricity here, plus it is only in the last couple of years that the govt introduced a rebate scheme to get everybody to install back-up batteries, so more have gone out and installed solar systems - the never ending cycle that is only going to make matters worse.

It took less than 4 years for me to recover the cost of installing the solar system from the savings made on the power bill.

 

[augustinetez]

One thing I left out in the above - the govt eventually spent taxpayers money on importing portable diesel generators (5 I think it was) because they "could be brought online fast when needed" and then promptly sold them off to a private company.

As far as I know, they have been mothballed and will probably never be seen again.

 

[gophert]

One thing I left out in the above - the govt eventually spent taxpayers money on importing portable diesel generators (5 I think it was) because they "could be brought online fast when needed" and then promptly sold them off to a private company.

As far as I know, they have been mothballed and will probably never be seen again.

That story has all the hallmarks of an urban legend. Any news report or public records on that one?

 

[augustinetez]

I don't deal in 'Urban Legends' - https://www.abc.net.au/news/2019-08-28/back-up-power-generators-leased-to-private-companies/11457824

You'll note the story says 'leased', the actual deal was way different.

 

[rjenkinsgb]

What about home "power bank" type units?
eg. As with the Tesla Powerwall type system.

Those take some of the excess & you can then use that stored energy when there insufficient sun or to charge an electric vehicle quickly without pulling so much power from the grid.

There are also regional systems. Some hydroelectric plants work "in reverse" during low demand times, storing power by pumping water back up to the power plant reservoir.

Or more extreme, city-scale battery storage like the system in Texas, with a capacity of something like 60 megawatt-hours, if I remember correctly.

There are a number of possibilities, it's down to the power companies and consumers adapting as technology changes.

 

[gophert]

What about home "power bank" type units?
eg. As with the Tesla Powerwall type system.

Those take some of the excess & you can then use that stored energy when there insufficient sun or to charge an electric vehicle quickly without pulling so much power from the grid.

There are also regional systems. Some hydroelectric plants work "in reverse" during low demand times, storing power by pumping water back up to the power plant reservoir.

Or more extreme, city-scale battery storage like the system in Texas, with a capacity of something like 60 megawatt-hours, if I remember correctly.

There are a number of possibilities, it's down to the power companies and consumers adapting as technology changes.

Its also about base-loading, load-leveling and the decreasing profitability (or return on investment) of trying to get every last photon to usable energy.

what happens if you have a hot steamy, rainy week or two and all batteries are tapped out and no coal-fired plants to maintain the grid at minimum voltages or more? Who sets the timing of the grid for all inverters to match phase? How do the multimillion dollar coal fired or nuke power plants make money as they sit idle or at their lowest possible output as the sun shines and homeowners feed the grid? Should the government subsidize them or pay them for being available as you would pay a technician at a help-desk (whether they are fielding a call or not) or a fireman (whether he his fighting a fire or not)?

 

[Nigel Goodwin]

There are also regional systems. Some hydroelectric plants work "in reverse" during low demand times, storing power by pumping water back up to the power plant reservoir.

I don't think the UK has any of those?, in fact we're pretty light on hydroelectric power at all - but we do have a few stored power stations like Dinorwig - which is basically a two way hydro electric power station, but without any water source at the top, all built inside a mountain. The only water is pumped up from the bottom during times of low demand.

It's open to the public, and well worth a visit - you drive in on a bus.

As I recall, when it's in standby (generators already spinning, so it can start producing in seconds) it takes 5megawatts off the grid just for that.

Making a hydroelectric power station two way sounds a pretty good idea, but of course you need a reservoir at the top and the bottom.

 

[shortbus=]

Should the government subsidize them or pay them for being available

Pretty sure they get subsidized now , don't they? Like the fossil fuel industy does, still getting the same kind of breaks they did back when they needed them, which they don't now.

 

[gophert]

Pretty sure they get subsidized now , don't they? Like the fossil fuel industy does, still getting the same kind of breaks they did back when they needed them, which they don't now.

Yes, in the US. The OP was complaining about Australia - I don't know the power plant subsidy scams/solar feed-in scams there. Schemes/scams? I think I've heard it both ways.

 

[Visitor]

Yes, in the US. The OP was complaining about Australia - I don't know the power plant subsidy scams/solar feed-in scams there. Schemes/scams? I think I've heard it both ways.

No, the OP was not complaining about Australia. The OP (that would be me) shared an article on an unintended consequence of an apparent solar power win – 100% powering of the grid by home solar installations. Yes, this happened in Australia, but it could happen anywhere as adoption of alternative power sources increases. The sooner we plan for this eventuality and devise methods to solve the control and backup reserve issues, the better.

 

[shortbus=]

The sooner we plan for this eventuality and devise methods to solve the control and backup reserve issues, the better.

When it will really take off is when the fossil fuel industry wakes up and sees their profits dropping.
I think it may be an Exxon(can't remember right now) TV ad that talks about how they are investing more in alternative energy now.

 

[gophert]

When it will really take off is when the fossil fuel industry wakes up and sees their profits dropping.
I think it may be an Exxon(can't remember right now) TV ad that talks about how they are investing more in alternative energy now.

Exxon, BP and Shell have all rebranded themselves as "energy companies" rather than oil or petroleum companies.
BP, for one, has made huge investments in solar and wind since the 1980s. They sold their BP Solar business in 2012 but reinvested in a different Solar business called Lightsource BP

Lightsource bp on track to develop 600MW solar hub in NSW, Australia | News and insights | Home

13 May 2021

www.bp.com

And wind

bp and EnBW launch ScotWind supplier portal to support offshore wind growth | News and insights | Home

11 May 2021

www.bp.com