Is it immediate? Sure, there is satisfaction that you are using 'free' electricity. But it does have an upfront cost. I calculated that it would take over 11 years to recoup the investment based on our current usage. Given we already get cheap night-time rates to charge the car and run appliances, it is hard to justify.

Like many UK houses, we have gas central heating too. I guess if we had a battery too (more investment) then we could switch to using electric oil-filled radiators, though they would not heat the whole house. And we could install a hot water tank.

I guess for new builds there is a real opportunity, but for an existing household I'm struggling to see how it works - and I want it to!

UK also has massive subsidies. I know someone who got a government subsidy, the company didn't complete the job, got paid for the government for the full job, and they calculated the payback was 50+ years.

At this point, I do not understand how anyone can possibly believe that the people advocating for this stuff are thinking in terms of economic (as opposed to political or social) returns. This stuff makes no economic sense and is already bankrupting the country.

Also, there is a legal requirement for new builds to have this now, this is with a massive shortage of housing, with a government that is a government of the "people" but has just put out the same housing targets as the last one and is running 75% behind annually. The scale of subsidies being given to these industries is probably tens of billions, green energy subsidies are now 5x larger than industry profits...this makes no sense, even with sky-high electricity prices (to be clear, it is consumers who are ultimately paying for this...we pay higher prices so that a lawyer somewhere can prattle on about leading a "green revolution" that is lining the pockets of donors).

Ideally, the problem will solve itself. People will get angry with increased energy prices, and elect politicians who promise to bring them down (The most effective and visible way being home solar subsidies, while reducing gas/coal).

I don't think it ever makes sense to switch to electric radiators. It might make sense to switch to a heatpump, but you need to avoid being hugely overcharged by the installers and there are flow issues if you have 8mm piping.

This ROI calculator looks reasonable: https://ukcalculator.com/solar-panel-roi-calculator.html - note that it subtracts the install cost for you, so any case where the final figure is positive is profitable. But of course that depends on whether grid prices go up or down in the next decade ...

Are you talking about rooftop solar?

For an 800W balcony system your background house usage is likely to be enough to self consume most of it.

You'd wouldn't be able to run even a small oil heater except maybe in peak summer.

It's a good match for working from home as it's a small amount of power spread over daylight hours.