[tjansen]

As soon as everybody is paying spot prices, balcony power stations are not economically viable anymore. Even today, on a sunny day, spot prices for electricity are either very low or even negative. The more solar power is available, the lower these prices will be. So your balcony power station is replacing electricity you could get for free anyway. At night, when you are not producing electricity, you still need to buy the expensive electricity from fossil plants.

The reason why personal solar installations are profitable is that you can buy electricity for fixed prices from your local power company. You pay the average of the vastly different low (or negative) prices during the day and the extremely expensive prices on windstill nights. Solar allows you to use your own electricity when the average is below spot prices, and get power for much less when the price you pay is cheaper than spot prices. It's like a state-approved scheme to play the market in the name of decarbonization while actually increasing everybody else's prices and possibly even CO2 emissions.

[tpm]

> As soon as everybody is paying spot prices

Which is never, because even then you are still paying some sort of taxes on top of the spot prices and also network fees.

The price of electricity from the network also has to include the price of delivery, while homemade electricity only has to recoup initial investment.

Of course this means given enough home installations (in places with enough sun) the price of electricity from the network will rise, more people will install their own stations, some will even disconnect, rinse and repeat. I read somewhere this exact situation is already playing out already in Pakistan.

[pjc50]

> spot prices for electricity

There are various good websites for showing the UK generation mix, but pricing seems less public. A lot seems to be done on day-ahead, which is pricing for the whole day not minute by minute. Is there a minute-by-minute ticker? Tariff?

(the reason I'm asking is that I'm skeptical as to how true this is for places that aren't California)

[tialaramex]

You can see spot prices at the top of grid.iamkate.com for example.

It would be nice to have some belated insight into how the bids look. Like maybe a few random hours released from a week ago?

Oh, and it's half hours. You can't buy or sell five minutes of electricity, just half hours, which is why your smart meter also thinks in half hours. 48 periods per day.

[pjc50]

Aha - that led me to https://bmrs.elexon.co.uk/system-prices , which shows that for the last week prices have been hovering in 80-180 range, and there was only one period of negative pricing during the day.

[stuaxo]

Wow, £100 per MWh and 12% is fossil fuels in the mix at 10:48am ... a bit more Solar adoption and maybe that 12% could go away, it's morning after all.

[mytailorisrich]

It's windy (41% wind). Solar is not great all day long and all year long in the UK (8% solar at the moment, it is a cloudy day).

[mytailorisrich]

To me this illustrates that with renewables (solar and wind) the key is storage. You want to grab all you can during excess production/very low prices periods and then use that for the rest of the day.

You can do exactly that by buying battery packs but (1) they are more expensice pieces of kit than solar panels and (2) capacity and output of DYI/plug in systems is very limited.

A quick check online also says that (in the UK) peak spot prices are usually 7am-10am and 5pm-9pm, which are basically when demand picks up or hasn't dropped yet while solar panels are useless...

[tjansen]

> You want to grab all you can during excess production/very low prices periods and then use that for the rest of the day.

Batteries help, but even that is limited in northern countries like the UK. If you look at the data, in July '25, solar produced 2.36 TWh. But in December '25, it was only 0.535 TWh: the output in summer is >4 times the winter output. So either you need to discard 75% of the electricity produced in summer, or you need truly gigantic batteries that store power produced in summer for winter. Both is not economical. Solar is far less efficient in the UK than in, for example, Florida.

[mytailorisrich]

In the UK wind contributes more to the grid that solar (not unexpected). Overall the issue with either or both is still that production varies widly over time including within a day.

With solar specifically you have the obvious day/night cycle, which makes storage required to make the most of it.

[vablings]

This is why smart meters are important to providers, they can more accurately model the spot pricing adjustments which means that you actually use LESS fossil fuels. Also most new meter installs support bi-directional metering