Grids in Germany if you're not a "typical household/office" with therefore atypical grid usage bill for peak power and energy separately; the billing related peak power is measured by averaging power over 15 minute chunks, and taking the worst one of a year.

Alternatively it's also practical for such solar situations to bill for market rate price of the energy in each 15 minute chunk separately; this doesn't correctly attribute transformer and other transmission equipment expenses between solar houses and non-solar houses, but it's still handling the grid tie solar load on the grid's power plants during periods of very little sun.

> averaging power over 15 minute chunks, and taking the worst one of a year.

What an interesting metric. Wouldn't even a very cheap and small battery (definitely small enough to keep inside an appartment) provide enough smoothing to, like, halve this peak number? You could rig it to not even output energy until you are beyond the current year's peak usage... How much money would you save this way?

I just feel this number is so prone to small mistakes (grandma plugs in the wrong things at the wrong times) and hacks (like the above) that the relationship between users' reward/punishment and the grid's health seems wildly disproportionate.

> market rate price of the energy in each 15 minute chunk separately

I am currently on a plan with 5 minute market rates, can buy and sell in (sell prices can go negative - as can buy, actually), all automated. At least I feel we am working with the grid, not against it, and we make a small net profit (before depreciation).