Theo wrote:

Andy Burns wrote:

It's more like a balancing power reserve

Why does buying low and selling high require subsidy? It's just arbitrage.

There are battery schemes within the national grid's "enhanced frequency
regulation" scheme, not found yet whether this one does, or if it's
another of their myriad balancing schemes.

Various EFR projects seems to cost between £7 and £12 per MW per hour
(odd units!)

Three other 10MW battery EFR have tendered for about 350GWh each over 4
years and come in at £2.7m, £3.9m and £4.2m contract values.

So probably that's the basis this pv+battery farm operates on, and the
less Wh it has to buy from the grid because it can get them from its own
panels, the more profitable it becomes?