[edent]

I'm in the UK and am currently being paid to use electricity.

My energy provider uses a tracker tariff which can change every half hour (it does have a maximum cap to prevent the issues seen in Texas). Prices are currently negative, so every kWh I use right now means the electricity company pays me.

Nuclear promised energy which was "too cheap to meter". But solar actually delivered.

[ahhhhnoooo]

If you had a big enough battery, could you sell electricity back to the grid later? Get paid to charge the battery, get paid to discharge the battery?

It seems silly, but actually... it's driving useful behavior I suppose. Then again, maybe a good government would notice this and just fast track grid storage rather than distribute that work to all the citizens.

[edent]

Yes. I have a 4.8kWh battery which is slurping up electrons. It charges either from our solar panels or from cheap grid electricity.

It discharges when prices are high. So it'll mostly go into my oven tonight. If export prices are high, it can also sell back.

Very roughly, we sell about 16% of our stored electricity - the rest is used by our home.

See https://shkspr.mobi/blog/2026/02/30-months-to-3mwh-some-more...

[rcxdude]

A lot of the value to homeowners is essentially arbitrage on the retail cost of electricity: when prices are high you're going to be paying a lot more to pull electricity from the grid than you would be paid to supply it, so you're better off using up the buffer yourself as opposed to paying for electricity from the grid.

[jonatron]

> If you had a big enough battery, could you sell electricity back to the grid later? Get paid to charge the battery, get paid to discharge the battery?

Yes, some people do this. There's even a startup built around the idea: https://www.axle.energy/

[fhn]

Sure you could. How much do you think they will pay you per kw? 1/10 what you paid them and they will charge you for using their infrastructure..at least in the US they do.

[dehrmann]

Someone at the utility went through the same math you are and decided it isn't worth it at scale. It's probably not worth it at small scale.

[ZeroGravitas]

The UK is world leading in battery rollout because someone did the sums and decided it did make sense at scale.

[dehrmann]

Or it is! And they can do it cheaper at-scale than you can.

[beng-nl]

Back of the envelope I did one time told me i could earn more by picking up cans off the street and trading them for the deposit.

Still, it would feel nice - after the initial cost- to have very cheap power (only charge when cheap).

[crote]

There is no such thing as "the utility" in Europe. It is legally not allowed for a single company to both operate (parts of) the grid and trade in electricity.

[Maxion]

Overall on it's own that isn't yet profitable to do, unless you're e.g. a wind producer.

[cjrp]

Yes, I believe some EVs allow this too.

[modo_mario]

I don't think that would ever commonly be viable or at least not for a long time. EV's are a lot more than batteries and are proportionally stupidly expensive. If the electricity net arbitrage was worth the degradation of the battery then .... companies would do it themselves and just build the batteries for cheaper at scale.

[edent]

It is commercially viable. A UK energy company already has a Vehicle to Grid tariff.

https://octopus.energy/power-pack/

See also https://www.ofgem.gov.uk/publications/case-study-uk-electric...

[modo_mario]

>A UK energy company already has a Vehicle to Grid tariff.

And is that actually worth it to anyone who does the math? An optimistic 161 pound saving compares to how many of my battery cycles for example? My car costs 50-60k so battery degradation is not nothing.

[edent]

Yes.

The arbitrage difference between filling your battery cheaply and discharging when prices are high is greater than any theoretical wear on your battery.

Even better if you are being paid to charge your battery.

[benj111]

The battery is already a sunk cost. Doesn't matter how expensive the battery was if it's already sitting on your drive.

I did a quick fag packet calculation and even today 10% of everyones EV battery would be enough to cover the grid for an hour. That's enough of a buffer to spin up gas turbines for example, so you can actually shut them completely off.

[modo_mario]

>The battery is already a sunk cost. Doesn't matter how expensive the battery was if it's already sitting on your drive.

My Hyundai Ionic 6 rolling battery costs 50-60k. Spending a cycle of it's battery is not a discardable cost.

Some will still take it but this seems just like a more deceptive version of those uber driver that get a pricey car and then find out that combined with maintenance, degradation/devaluation and other hidden costs they don't actually make that much driving around.

>I did a quick fag packet calculation and even today 10% of everyones EV battery would be enough to cover the grid for an hour.

I presume you deduct more than half of the rolling battery capacity out there. You can't discharge those to 0% shouldn't charge them to 100%, many won't be charged fully (or connected) + If I need to leave in the morning like most I don't want to necessarily be dropping charge into the grid.

[benj111]

>My Hyundai Ionic 6 rolling battery costs 50-60k. Spending a cycle of it's battery is not a discardable cost

Problem is we don't have good data on actual costs. So we don't know if we're talking about something substantial or something hypothetical. Absent that data I think my comment is fair.

>I presume you deduct more than half of the rolling battery capacity out there

No. We are talking about 10% of battery capacity so your battery at 80% would only need to go down to 70%.

A problem we have in the UK at the moment is that we have gas turbines running even if not needed just incase the wind suddenly drops. It takes (or can take) about an hour to spin up a turbine from cold. So a battery supply that could cover that hour would mean we could use a lot less gas. Most of the time it isn't even used, and if it is, most probably won't use that full 10% and once the gas turbines have spun up it could recharge the batteries.

To link it back to the earlier comment, even if the maths is bad for EV as battery storage, you can still use it as battery of last resort. It would be expensive, so ev owners would still be up on the deal, but there would be a system on place to actually use them when actually needed.

[benj111]

Like an EV....

[jonatron]

Batteries are getting affordable too - Fogstar do a 16kWh battery for around £2000. Plus, grid scale iron-air batteries sound promising.

[thebruce87m]

Have you got one? Looking for installation options.