By P Gosselin
Photovoltaics are escalating power grid instability in Germany, thus increasing the risk of regional blackouts. Too many cheap, uncontrollable systems from China are flooding the market.
“Millions of solar installations will have to be torn down”
Hat-tip: Alexander Raue
In Germany there are growing fears of power grid blackouts. The reason: The effects that the “rapid expansion of photovoltaics” is having on grid stability.
“Many countermeasures will not take effect for years,” reports the online business daily Handelsblatt. “In 2023 alone, the number of photovoltaic systems connected to the grid rose by 30 percent to 3.4 million units, the Federal Statistical Office announced on Monday.”
As more and more small-scale systems get installed, the more unstable power grids are becoming, experts are warning. Because wherever more electricity gets produced than consumed, the grid can collapse.
“In the worst case, this could mean local power cuts, warns the Association of Municipal Enterprises (VKU), which brings together many municipal utilities,”reports the Handelsblatt. Small, private rooftop systems have gained wide popularity across Germany, The problem however, is their technology.
“The majority of systems cannot currently be switched off automatically if too much electricity is produced in certain phases and regions,” the Handelsblatt adds. This is leading to grid overloading and instability.
Online news-video publisher Alexander Raue also blames the grid instability problem on “cheap solar systems from China.”
“I believe there’s a well-functioning technology available -already today- but it’s considerably more expensive. And because the market is being flooded by millions of cheap products from China, thrifty German consumers are snatching up the Chinese junk and are thus putting the German power grid in jeopardy,” says Raue. All of this is being promoted by Germans Economics Minister, Robert Habeck.
“The electricity grid operators have now issued an explosive blackout warning about solar power! Millions of solar installations will have to be torn down, as Habeck’s favorite project, of all things, means the collapse of Germany!” Raue comments.
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How difficult is it to manufacture a good inverter? Has anything else to be changed?
How about mandatory smart meters that can be remotely switched open for all rooftop solar installations
Not a question of goodness of inverter. Problem is intermittency. Even in high summer the supply is sharply peaked, not in sync with demand. In winter it vanishes and what there is is even more sharply peaked. You need some way to turn it off when peak output hits low demand. That is what the piece says is lacking in the cheap Chinese ones now being installed.
Even if you have that, you will still have the opposite problem of no supply during a peak demand period. Batteries are the only solution to that.
Pretty much all solar is good for…recharging batteries
That and running calculators
Yep, I have solar charging my 5kWh batteries at home and running my house on batteries. When batteries run flat it connects to grid. Working fine…
So you’re on the grid most of the time.
I use 45 KWh daily so 5KWh would last about 2 hours and 40 minutes. The remaining 21.34 hours would be Grid Sourced
And that is provided you have sufficient cell capacity and solar availability to recharge a 5KWh battery in 4 hours…sufficient sun from 10am till 2pm
Perhaps I could hang a Tesla on my garage wall and cover my entire yard with solar panels and perhaps produce the 45KWh A day that I use
That would only cost a couple hundred thousand dollars and take 50 years to pay for itself
Of course I would need to replace the panels at least 3 times in that 50 years so likely longer to break even
Actually, you’re too optimistic ’cause you flat-line your consumption, which it isn’t. Refer back to the duck curve, your house is a microcosm of that demand curve, and your peak likely doesn’t occur at the same time as the solar production peak. So when the solar output approaches zero at about 6:00 pm (sun time) and that’s when your peak occurs, your battery likely lasts <1 hour. Then you’re back on the grid again and contributing to that oddly shaped duck curve your grid provider struggles with daily.
For sure, clouds play into the intermittency, wrecking havoc across the grid with voltage fluctuation.
Inverters need an external signal to sync up with. As renewable energy sources like wind and solar become more dominant they not only create harmonic distortion themselves, but react very rapidly to the distortion created by other sources and start syncing to other sources on the grid. They can also react to reactive power when the grid load factor gets out of whack. This creates instabilities on the grid and the problem only increases as the amount of wind and solar increases and it can become very dangerous.
The effect of renewable energy incorporation on power grid stability and resilience https://www.science.org/doi/10.1126/sciadv.abj6734
Why is the proponents of “Renewable Energy” shunning, dismissing, ignoring both Active and Passive Solar Water Heating Systems? Hot Water is the second largest use of “Energy” for the typical home. DUHH, NO Government Subsidies. In areas were below freezing temperatures are rare these are very inexpensive as you do not need to use a non freezable medium to heat the storage tank. Even the Active systems are more economical than a solar system. Don’t need batteries as the Hot Water tank is the storage. You can use Electricity or NG as “Backup” or even your existing Baseboard Furnace.
You want to be selective of what you use. If you select NG then you will be paying your NG Utility for the connection even when not using the NG. However, you are much more likely to lose Electricity during severe weather events. A NG furnace does not work well without Electricity. However, I have used NG at least five times over the last 20 years to keep my home bearable ( about 60 F) by filling the bathtub(s) with hot water and or plugging the drain while taking a shower.
UK. A hot water cylinder needs a header tank too both of which take up space and require more pipework. In peak usage times, the hot water quickly gets used up so better be first in the shower, because reheating takes time.
This was typical in UK homes before the 1980s, when demand ‘combi’ boilers became popular for instant (relatively), continuous hot water and space savings, particularly in flats. Many home owners replaced the old system with combi system, benefits bring convenience and economy
New build homes just don’t provide space for the old style system and with the added clutter of solar panels/heat exchanger. In Northern Europe solar panels are just decoration.
But why are we replacing what works perfectly well, with what doesn’t work as well in order to solve a problem that disent exist… at vast expense?
Utter bollocks
I thought about making a solar hot water system when we were renovating out last house but the more I looked into it the less sense it made. The problem was the same as PV—a mismatch between when the sun is doing its thing and when we wanted hot water (before sunrise).
yes, there were ways to overcome the problem, but it wasn’t economical.
Does calling the Chinese manufactured systems “cheap” have anything to do with the issue discussed? How does their purchase price affect the analysis, other than more people can afford them?
Cheap can infer lacking features.
As an example, a quality inverter will have a maximum voltage threshold and will also have a near sinusoidal output.
A cheap inverter will have a less accurate upper voltage threshold and may have a modified square wave output.
Would you like to run your high tech devices on an inverter that may top out several volts above the specified maximum or with a wave shape full of very high frequency harmonics?
Almost all my electronics run off switching power supplies. It pretty much doesn’t matter what you feed them with as long as it’s between 100v and 240v.
a switching supply necessarily strips out harmonics as it converts AC to DC, because the class D amps that actually do the conversion are super noisy. That’s what the big caps are for.
Cheap can also mean inferior quality.
Remember when it used to be “must have been made in Japan” back in the late 50s as Japan was learning how to produce transistor radios?
All my kids could turn a summersault long before they could tie their shoe laces. Several Japanese friends had kids that could tie their shoe laces long before they could do a summersault. We thought they must have been bred to manufacture transistor radios.
There are actually two problems. The article focuses on oversupply. But renewables also provide no grid inertia. As their penetration grows, grid inertia declines and the grid becomes unstable. Conventional generation automatically supplies grid inertia via angular momentum.
True, but a good inverter design could probably provide a good semblance of a grid inertia.
Inertia is the ability to keep the frequency the same and the phase to remain locked. Since an inverter is locked to the incoming waveform and not to a clock, it will only ever follow the wave.
If you were to program the inverter to run several degrees in advance of the incoming wave then it will always be out of phase. This would be a partial load on the grid requiring the grid to pump current into the inverter to try to make it slow down.
If you were to lock the inverter to a crystal controlled frequency and phase, then a true phase shifting event, (eg a brief but large short on the mains), would result in the crystal locked inverter being OUT of sync with the mains, this is a load on the grid, not a supply. How long should it stay out of sync for?
There is no simple way to use an inverter to provide grid inertia.
On larger scales, you could use the DC supply to run a DC motor and an AC generator on the end of the motor shaft, mimicking the turbines at a power station. The spinning mass would provide inertia but the costs would rise and the this excludes all sensible household budgets.
Eng-Ian. I agree with all you say here except the part about grids pumping current into inverters. No they don’t. It is voltage that the grid transmits, that is what electrical energy is. Current which is the flow rate of electrical charge is the movement of electrons which hardly move and don’t really go anywhere.
Also, electrons do not get pushed across the gap in the field windings in a transformer. Induction is voltage as Michael Faraday discovered.
The electron drift is very slow and a 1 amp current in a 2mm cross section of copper wire will push electrons at about 8.33 centremetres per hour. If electrons were the size of a golf ball they would be 15,000 miles apart and they never touch each other – they simply drift within the the crystal lattice of a metal. I am quoting a physicist here, although I used to operate complex electrical equipment on big aircraft where management and understandin of reactive power was important.
I should add here for those who might not know, voltage is the movement of photons along outside the wire. The electromagnetic force comprises two wave forms, electrcial and magnetic at 90 degrees to each other. The electrons are absorbing and emitting photons all down the wire.
I’m having a problem with both your responses here. In the first on you say that electron drift is about “8.33 centremetres per hour”. But since Eng_Ian was talking about AC power, there would be no such drift. The electrons go back and forth 60 times a second, effectively traveling nowhere.
In your second response, you say voltage is the movement of photons along the outside the wire. Why would they do that? They have no charge, and electron emits them when it is changing to a lower energy state, without direction being implied.
I think you are mixing up two or three different ideas, but I’m not sure I can identify the ideas you’re mixing up.
Ex- KK
In both AC and DC power the electrons drift but only very slowly. In an AC circuit they wiggle back and forth without really going anywhere. In a DC circuit they drift, but very slowly, but against the direction the power is moving. Photons are the electrical energy and they do move along just outside of the wire at near the speed of light – for the most part they do not fully escape the wire, some do, but most are referred to as “virtual photons”.
The point I was making was that current does not get pumped from the grid to inverters, that is electrons do not get sent from a power station through transformers to someone’s inverter. It is voltage in the form of photons that is the source of energy. Read up on Quantum Electrodynamics to get a better understanding. You would be surprised how few people know that voltage is the electromagnetic force made up of photons and that is the same force that emanates from a magnet.
The electromagnetic force of photons consists of two waves at right angles to each other travelling at just under the speed of light, but electrons are not electrical energy, they are the charge carrier.
CG. Where is the instantaneous energy going to come from to simulate angular momentum in a solar installation. The panels are already at maximum output and can not supply more power.
Red, technically, AC is a sine wave. There is a lot of room between peaks where the panel can supply additional power.
Eng_Ian, I agree that there is no simple way for an inverter to model inertia. I don’t even know if it has ever been done.
A few of these
https://en.wikipedia.org/wiki/Synchronous_condenser
The reason the power is AC is for long distance. Filling in between the peaks does nothing. Line losses negate that or transformers will not boost the voltage depending on specific details of how the “room between the peaks” is filled.
George,
few seem to grasp that inertia is not an answer in itself; Inertia is part of any conventional generator but it is only a frequency damper. There must also be a variation in input to compensate for varying demand on the grid.
Not quite a parallel but the flywheel in a motorcar engine smooths the power impulses but turn the engine off and the flywheel’s inertia won’t keep the engine running.
Same, but simpler example, is a steam engine.
In the UK the grid operates at 50Hz with a tolerance of less than +/- 1Hz. Outside that you get shut down.
Electronic frequency control cannot maintain that tolerance as they themselves are affected by frequency variations.
I seem to recall several different prescient people over the years submitting to WUWT that “Renewable” energy systems like Wind Turbine and P.V. should be tested on small isolated grids to identify their efficacy on the grid, if any, and to identify the respective problems associated with adding such intermittent and unreliable power sources to a grid. It’s good that Germany has volunteered to be the world’s test bed, albeit on a larger scale than some were thinking necessary. But the bigger test the better.
Question: Will the rest of the world even take notice? Here in the US, the Deep State powers that are forcing brown-stain “Green/Renewable” energy still hope to destroy America, so those subsidies will probably keep on trucking thru our city streets, mowing people down in their wake.
No, we are saving the planet. Don’t forget, we have to save the planet. Three whole generations of western people all got taught that since kindergarten. Remember, there’s no place like home, evil people killed Bambi’s mother and sea otters are very cute.
Their have been two such tests I know of. King Island, Tasmania and El Hierro Island, The Canaries. Neither gets much more than half of their electricity from their renewable systems and the cost of this electricity is very high.
The original El Hierro design goal (touted across the EU to get needed subsidies) was 100% renewable. When this proved infeasible for various reasons, it was reduced to about 2/3, the remaining 1/3 being legacy diesel. 50% is still a real world failure despite the subsidies.
I think they approached this from the wrong direction – the design is fine but the number of people is not. You need to remove people until it works.
That is the end game goal.
Germany’s Energiewende is not a very good test. The reason is simple. When they have wind over generation, they dump the excess (at a negative price) via interconnector into Norway. Norway simply throttles back its hydro and saves water. Then when wind fails, Norway opens the spigots and sends hydroelectricity to Germany (at high prices) to make up the deficit. The system works electrically, but is a terrible economic deal for Germany.
Keeping track of renewable energy adventures is like watching grass grow. It goes on for years which bleed into decades.
You don’t have to tear solar down. You just have to remove it from the grid. It still works as it always did, about 4 hours a day.
People should use household solar to power their homes via battery packs, not the grid.
Disconnect household solar from the grid and get rid of the problem.
Household solar may not provide all the electricity the house needs in a day, and the home may need to use a little electricity from the grid to make up for the shorfall, but it will cut down on the cost of electricity for the home.
You overlook: household solar only becomes economically viable when a taxpayer funded subsidy is available to contribute towards capital cost, and feed-in tariffs are sufficiently high to amortise the balance cost over a few years, and then return an income as the feed-in cost will be higher than the purchase price of electricity from the grid when needed.
The expense to the supplier of the feed-in tariff is covered by increased prices through other consumers’ bills, and subsidies come out of the taxpayers’ pockets.
Home solar is parasitism, or legalised plunder of others perhaps. We live in a shameless society.
In the US, household solar only ever cuts down on costs with large federal and state subsidies. If you disconnect it from the grid then you need to add expensive batteries and it makes even less economic sense.
> “The majority of systems cannot currently be switched off automatically if too much electricity is produced in certain phases and regions,” the Handelsblatt adds.
This is not about “instability” but “control.” Who contributes, when. Does anyone think industrial scale photo farms are going to be throttled at the same rate as residential rooftops?
Small rooftop solar systems should not be allowed to send excess energy into the grid. The grid is too important to be put at risk just so some joker can save a buck or two on his power bill. Especially considering that the solar system has most likely been subsidized already. I am tired of paying for someone else to play around with unproven power supplies. Forget about smart meters, they are a bad idea. No one else should be in control of the power you are already paying for. Regulators have a clear responsibility to ensure the power supply is equal to demand, affordable and reliable without screwing up the grid.
But supplying (and getting paid for) electricity from roof to grid has been the single most important reason for individuals to get solar panels. That way they put money in the bank in summer and take it out in winter ( or peak/ off peak during the day). No use of putting them up if A: they can be remotely closed off by Solar companies and grid operators in case of oversupply which always happens at peak sun summer and B: they get no renumeration. Solar companies are now rolling back on that because the grid operators don’t want the excess electricity. People are currently on 2 or 3 year attractive contracts that will run out. Most debt financed solar panels run between 8 and 10 years to get even and rely on subsidies and renumeration. And a high price of hydrocarbons. The early adapters reaped the benefits. Even though the price of solar panels themselves have come down it still does not really compute if all the other factors weigh the scale in the opposite direction. And doubt is still a killer..
I have a lot of concern for a healthy grid. If people want rooftop solar that is fine with me but pay the full cost yourself, store your excess energy or let it go to waste, I don’t care. Don’t look to me to financially support your bad decisions and don’t do anything to endanger the grid. It is just that simple.
It’s unintended consequences again of shoot – ready – aim. Or “how to increase cost and reduce availability and reliability of a once stable, reliable energy system.” The Greens don’t have a clue of energy requirements, they just know what they want.
“I believe there’s a well-functioning technology available -already today- but it’s considerably more expensive. And because the market is being flooded by millions of cheap products from China, thrifty German consumers are snatching up the Chinese junk and are thus putting the German power grid in jeopardy,” says Raue. All of this is being promoted by Germans Economics Minister, Robert Habeck.
You get what you pay for.
This is a false report.
All solar inverters export power by producing a voltage that is higher than the grid supply power. As more solar gets installed, the voltage gets higher, but only to a limit.
Once the voltage gets too high, the solar can’t export power anymore. It is self- limiting.
Where does the electricity go to,then? Do the panels simply stop producing power? If so,that would be great. Do you have any numerical parameters on this?
It is controlled by the ‘smart’ system to protect it.
So the voltage is going all over the place.
Great, just what is needed. /s
Its not just voltage – phase also matters.
and frequency
That is true for individual systems and it keeps that system safe just like wind turbines that switch off when the windspeed is too high.
But you have to think holistically considering all the factors in the total system. Grids HATE fluctuations. The system relies on super steady parameters. Increase solar and wind? Destablize it. By default. There is no way to circumvent. You can take measures to control it but only up to a point. You have to admit the inherent limitations within and that includes (current) technology. And we have to consider scale. These are double and triple whammies outlined by many technicians and system analysis experts. That is a mountain which summit you cannot cross. Unless you blow it up of course, and live w the consequences, some of which some people w actually welcome. Spanner in the works mentality. Everything for the ‘good’ cause, right?
“like wind turbines that switch off when the windspeed is too high”
Here’s a dumb question- if the wind speed is too high- and the turbines are switched off- are the blades still turning but not generating electricity- or do the blades stop turning? If they stop turning, doesn’t that put a strain on the blades? If the blades are still turning but not generating power, won’t the very fast spinning potentially damage them?
The blades stop turning..
As JZ mentioned, doesn’t that put strain on the blades? Their shape would make them “want” to turn. So how are they protected against that strain?
The question JZ asks is important because with the passage of thunderstorms the wind comes from many directions and regardless of blades being in feathered positions they can still be made to turn and under a downburst all will be pushed down towards the ground. In storms associated with fronts the wind veers 180 degrees instantly and no structure can withstand that continually.
This is the reason there are large numbers of gear box and bearings failures which are never reported.
Now is the time for those who know what’s best for us to rise up and save us from ourselves.
All this is about on grid rooftop solar. Nothing of this applies to off grid or hybrid rooftop solar with battery.
I have one on my roof, in service almost three years. Providing me around 72% of my yearly electricity needs. I’m 49 degrees north, not much sun in the winter, there goes 20% of my electricity.
In places like California it is not a problem to provide 98% of yearly household energy needs with small system. Remaining 2% represents around 7 days a year, easily coverable with generator.
I’m not speaking here about heating, for this I have natural gas heater. Although I’m able to reduce like 25% of natural gas costs using AC for heating running on solar electricity.
Your system runs pretty stable. But for this one needs to consider investment costs and benefits. Assuming off grid solar panels the financial net benefit can be calculated for both battery connected systems and none. There are some uncertainties lurking. It is wise to not completely rely on solar alone. The solar system seems only beneficial if hydrocarbons are expensive. Considering solar investment including redundancy and time limit constraints (batteries, solar panel efficiency, actual tech limitations) make the equations not as simple as one might think. Using back of the envelope calculations one might scratch one’s head and think twice. In the old days investment in energy systems were way more consistent over time. They ran 30-50 years with (simple mechanical) replacement parts available and NO computer tech. Hell, when my mum died in 2016 we had to remove the gas heaters that were installed in…1971! Modern tech is complicated and vulnerable. Just ask yr car mechanic!
I agree with you 100% about reliability of the system, hence I designed my system as sturdy as possible. Victron inverter and MPPT, they are known for reliability, producer is giving you 5 years warranty. When I built my system, total costs were around 4500Eur. Today I could build much better system for 2500Eur.
So far my system produced energy equivalent 1350eur. My system should return in around 9 years. When built today it would return in around 5 years. I have 16 euro cents per Kwh, quite low, return rate with higher prices of electricity would by much faster.
It is hybrid, when my battery runs flat it connects to grid.
During summer I have surplus of electricity, my normal consumption is around 12kWh per day. But during 4 summer months I have gain around 25kWh daily. So I’m just “vasting” energy as I know, I have hot tub which I’m keeping at 39C, my two AC’s are running whole days.
My 5kWh Lifepo4 battery has already 650 cycles, should work till 4000. Classic Li-ion would be already dead.
And all this with 8 panels – 16m2 on main roof and 4 panels – 6,5m2 in my garden.
The issue with (non grid connected) solar is the excess during summer when your energy needs are lower (f both heating and lighting) and the need f extra energy in winter when you dont get much energy from solar. Better if you live in warmer ( but not too hot) areas for cool air conditioning.
My brother has 16 solar panels on the roof of his barge, grid connected. His only money saver is summer solar electricity to the grid. He looks like another 9 years of payoff to get even IF things stay the same. And that IF gets iffier every year. It’s not quite like buying a car, pay off the loan and reap the benefits for another 5+ years i think.
I really hope that 5 years return on investment and 10 years of (steady?) benefit will work out f people. I have my doubts. I do actually use the car analogy. We always assume technology will get both better and cheaper. But there is a scale. Just look at batteries alone. Not much improvement. No real breakthroughs, just promises and prototypes ( which do not count). And economics, computer tech, supply chains etc. The opposite of certainty..
What I was trying to say here, that for example Germany with 0.30Eur/kWh price of electricity and 2500Eur solar system you can get pretty fast investment return for average household, somewhere around 2.5 years. With 2 years universal warranty in EU this is practically without risks.
It is only needed to count and fit system exactly for your situation and fast return.
I’m not fan of on grid systems and getting money from distributor for electricity. You depend on unpredictable partner.
We’ve got a very favourable Med climate for solar yet my nameplate 6.64kw rooftop panels can produce around 44kWhrs on an ideal sunny day but only 1.8 in winter but that hides a multitude of fickle sins on a daily output graph. We’re all going on smart meters with TOU billing ultimately to try and manage the impossible but tender prices tell the story-
Wholesale prices surge as wind and solar output falls to zero in South Australia | RenewEconomy
We all have to pay for the new meters plus spaghetti and meatballs grid as well as ever more batteries and synchronous condensers to hang it all together and yet we still bludge off interstate coal as they imitate us closing down coal. The fallacy of composition doesn’t enter their tiny pea brains as they double down to disaster. The only plus is when it all goes fizz their whole woke Marxist cult goes with it as their house of cards folds.
It’s physics Cap’n, and I cannae change the laws of physics. Scotty.
Climate change, it’s science Jim, but not as we know it. Bones.
Sounds like it’d be similar to driving a car with an intermittent fuel pump.
You can step on the gas peddle but the pump may or may not be pumping up to speed or at all.
Allow the nonsense to continue long enough and it will collapse under its own weight.
Unfortunately people will suffer as a result.
The only place for ‘renewable’ energy is in a museum
With roof top solar there’s a safety concern rarely mentioned.
A house fire.
They can cut off the house power from the grid before they start spraying water all over the place. Maybe even cut to solar panels’ output from the rest of the house.
But, if it was daytime, each panel’s output is a danger to firemen that need to go on the roof to put out the flames.
I can’t imagine any of our guys going up on that roof with live panels like that. Probably hit it with a deck gun from a distance instead.
Don’t they sometimes need to punch holes in the roof to prevent the buildup of volatile gases to prevent “backdraft”?
Not necessarily to prevent backdraft (opening anything to the exterior in a pending backdraft is quite dangerous – and there are usually other easier ways to ventilate before it gets to that) but roof ventilation can be used to help control the direction of the fire to make it easier to control. Especially on larger structures.
If you have rooftop solar, we’re probably not doing that.
Thank you. I’m not a firefighter. But I know that volatile gases won’t ignite without both a source of ignition and oxygen. In a house fire, those gases can build up over a smoldering fire but no “flash” until a door is opened and it gets oxygen. I extrapolated from what little I know as to why firefighters punch holes in roofs.
(Guess I’ve watched too many movies!)
PS Sounds like you are or were a firefighter. Thanks for what you do.
You have the idea of backdraft pretty right, and your extrapolation is not unreasonable at all! It’s more a matter of time – roof ventilation isn’t very fast and backdraft conditions can happen in only a few minutes.
There are ways to approach it while accounting for the blast, but you don’t want to be anywhere near its path!
And, my pleasure to serve!
This doesn’t make sense.
Don’t German household Solar Systems have Batteries with Inverters that stop sending electricity to Grid when the Grid rejects it?
Surely China’s Grid would require such inverters…?!
Why can’t the German Grid reject unneeded surplus electricity? All Grids control electricity fluctuations as we open & close consuming equipment.
Build pumped storage hydroelectric systems to sop up excess power and even out the flow.
From ‘The Future of GB Electricity Supply, GWPF
In 2012 National Grid issued a briefing note Solar PV to DECC on the potential impact of solar PV on transmission system operation and balancing. In this they note:
. . . at the start of the [power] ramp up [in the morning], there could be no fossil generation synchronised apart from that providing frequency response. This will make the management of the ramp very difficult using plant that has just synchronised, wind, pumped storage and interconnectors. […] To maintain inertia, fault levels and HVDC commutation, Wind/Solar output must not exceed 60% of network demand. […] With 22GW solar PV the system would require an unacceptable dependence on the ability to export over the interconnectors, or the construction of additional storage.