But it means you are simply exploiting the "normal" electricity grid this way by using it when your solar doesn't work and batteries run dry - that is, when the

But it means you are simply exploiting the "normal" electricity grid this way by using it when your solar doesn't work and batteries run dry - that is, when the cost of elecitricty in a normal grid, with the high penetration of renewables, is highest. You do the normal capitalism thing: privatise the benefits, socialise the costs... And the higher proportion of renewables in the grid is the higher is your upside. If you want to completely stop using normal grid and rely on solar alone, you will need to overbuild your solar so massively, you won't be able to afford it (and will run out of land, too). Cost of electricity produced will be several euros per kwh, and a simple calculation shows just how massively unrealistic it is.