Bird on a Fire wrote: ↑Sun Sep 26, 2021 10:51 am
Obviously the UK will never be generating 100% of its power from solar, or anything close. But something like 10-20% is probably imminently achievable, as part of a diversified energy mix (Germany is at 8% already, for instance, though it's a bit sunnier).
Remember, that is 8% of current electricity production. When you decarbonise, electricity production needs to increase by a factor of 2 to 3. Maybe more in Germany given their relatively high coal dependence relative to us.
PV production can get very large in Germany on a clear sunny day. Germany has a lot more pumped storage than Britain, because run-of-river hydro-stations, such as Germany has many of on large continental rivers like the Rhine, Elbe, etc, are easy to retrofit pumped storage. Nevertheless its system can be overloaded on a clear sunny day. Installing very much more PV in Germany is problematic. Already it is a problem to absorb the supply during the brief high peaks of supply.
Yes, we need a diversified energy mix. But if it is true, as that paper suggests, that PV and electrolysis will get order of magnitude cheaper, while wind only gets a bit cheaper, then PV and hydrogen for time-shifting kicks wind out of room, for bulk energy requirements. It will become profitable to pave the countryside with PV cells when they are cheap enough, even in dull Britain.
And importing either hydrogen direct from sunny places, and/or electricity by interconnector, will get cheap vs lots of wind turbines in Britain. Unfortunately getting electricity imported in large quantity via France from places further south will not be easy.
Bird on a Fire wrote: ↑Sun Sep 26, 2021 10:51 am
That would be a mere 0.25-0.5% of the country, which is less than half of the built-up area. Suggests that rooftop solar could be pretty viable compared with building new large-scale installations.
The key issue is timing. Large reductions to emissions are needed by 2030. What's the quickest option for the UK out of
A) lots of rooftop solar
B) fewer, larger installations
C) building solar in sunny places plus long-distance interconnectors.
My guess is that C is probably too slow for immediate reductions. But would be a good thing to get moving on, for when other projects reach the end of their life.
A) has the advantage of making people less dependent on the grid, reducing vulnerability to power cuts. Could be especially popular in rural areas, where the roof area to occupant ratio is conveniently higher. Especially as domestic solar tends to be bundled with battery storage.
B) would probably be more efficient in terms of economies of scale, depending on who's in charge. The UK doesn't always do large infrastructure projects super efficiently.
Of course, large installations could also be situated on large roofs, combining A and B.
I think you might be over-estimating how much of built-up area is suitable roof. They are a small fraction of built-up area, remembering that built-up includes roads and hard-standing around houses. The hard standing around my house - drive, garden paths, is as much as the area of roof. And on top of that there is public road, etc. Then only a fraction of roof is suitable for installation.
I didn't even think about roof-top solar after the council turned down the large south-facing roof, which would have made it very attractive. But now that I know that W & E facing roofs are also valuable for solar - because electricity is more valuable nearer sunrise and sunset than at midday - then I kind of regret it a bit that we didn't think about it at the time of putting the roof on, when it would have been cheaper easier. Though I did feel somewhat morally averse to the idea of taking the government's subsidy for solar, which I knew was unaffordable in the longer term and PV panels were a lot more expensive in 2007. But now they've gone the other way, and solar installations have stopped because there aren't even economic.
So, to get rooftop solar going again, we have to make it economic for people to do it. And it ought to be required on new buildings, including commercial, with a suitable aspect, though that will be resisted if it is not economic.
Unfortunately making solar panels commercial runs opposite to one of the other changes we need to make for decarbonisation, and that is electrifying heating. Currently electricity is burdened with taxes, and gas isn't, so a heat pump is always more expensive to run than a gas boiler for a given level of insulation.
It becomes a no-brainer to put PV on when it gets cheap enough. But how do you drive it towards cheapness? As a nation with a dull climate, I rather suspect this is something that has to happen elsewhere first, where it is much more economic in the short-run. Massive extension of PV panels in Britain is unlikely to happen just yet in Britain, certainly not in time for the artificial deadline of 2030.
Bird on a Fire wrote: ↑Sun Sep 26, 2021 10:51 am
Thinking in lpm's resource terms, trained solar installers are probably the limiting factor. While the government are organising a training program and the fine-tuning policies to help accelerate these installations, are they better off being used on decentralised A-type projects, or concentrated on B?
I assume the number of fitters per unit area of panel is much higher for rooftop solar.
OTOH neither the government nor industry is working fast enough at the moment. The advantage of A is that sensible entities can get on with things without waiting for the big boys to catch up.
People to implement it is a huge issue in all of the kinds of large infrastructure changes we need to decarbonise. PV panel installation is but a small side-issue in comparison to insulation, heat-pumps, nuclear power stations, etc. It doesn't help that the largest construction project in Europe, HS2, is sucking up so much of our construction resource to so little benefit.