The problem with solar isn't the night. Getting enough batteries to cover that is totally doable. The issue is the winter. And not even because of fewer daylight hours - on sunny winter days there is usually still a good amount of solar.

The problem is its often very cloudy in the winter. In the UK in winter we regularly have periods of 5 cloudy days in a row where solar output is virtually zero.

I don't know what the answer to that is. In a calm cloudy winter week all renewables and battery storage are totally screwed. Space based solar is a scam. Maybe we just have to live with it until fusion works (if it ever does).

(But it's still academic at the moment because we're still far from the point where building more renewables is a bad idea.)

It's unfair you're being down voted, you're right. I used to think that we could get by with just solar wind and batteries, but then after collaborating with people on an ideal energy mix the numbers were obvious: there is a (small) fraction that cannot be covered. Not with storage (the discharge cycles are so few that the cost is prohibitive. How can a battery pay for itself with 10-20 discharges a year? And this applies to any kind of battery that needs to be built, including hydro). Likely there will need to be some baseload nuclear (which then increases average prices, since to make it economical you need to buy all the electricity it produces, and so it partially displaces renewables). The alternative is overbuilding solar+wind+battery something like 5/8 times the average need. Maybe if the prices drop enough that could be feasible.. The big win would be if there is some way to get predictable power at a lower cost than nuclear (e.g. tidal), which could be used to smooth the troughts, or alternatively a low capex but potentially high opex solution which is turned on only when needed (gas is an option, but not co2 free. And sizing the power needed is not super cheap, although now it's not a problem since we have enough gas capacity which is going to be displaced, so it won't be needed to be built)

Regarding long term storage keep an eye on the UK's Cap and Floor scheme which offers guaranteed revenues to long term storage technologies [1].

Page 7 of https://www.ofgem.gov.uk/sites/default/files/2025-09/LDES%20... lists the technology types of the project applications. The majority are Li-Ion BESS, but there are also other battery chemistries and Liquid/Compress Air Storage

1. https://www.ofgem.gov.uk/press-release/super-battery-project...

Just over build the solar. Build out solar so demand in winter is met.

Use the excess power in summer for some kind of industrial use.

> In a calm cloudy winter week all renewables and battery storage are totally screwed. Hydro doesn’t really care about a calm cloudy winter week and is the reason my state was 100% renewable last year. So it’s definitely not a problem for ALL renewables.

> In the UK in winter we regularly have periods of 5 cloudy days

True, but then for the UK solar power isn't the right thing for winter, hence why we need a massive mix of other stuff.

Also we have the advantage that france isn't that far away.

In the UK battery is about grid stabilisation, as in making sure that it hums at 50hz rather than 49.

Keep some of the existing natural gas plants around as an emergency reserve. Run them on hydrogen or hydrogen derivatives for zero carbon fuel, if the emissions are large enough to matter.