Here’s what I’ve been able to achieve so far. Blue bars is my consumption which I’m able to fetch from the power grid operator and green line are the spot prices. You can see nice consumption peaks when the prices are lowest.
July 26 and 27 were hugely exceptional days in Finland in terms of the spot prices as there was a lot of wind power and at the same time the Baltic countries had planned maintenance in their power grid which meant that they could not import electricity from Finland which they normally do. I think we washed laundry something like 4 or 5 times, cleaned the oven with pyrolysis and so on.
My electricity contract is not directly bound to the Nordpool spot prices (i.e. spot price + margin). Instead, I have a contract which is 14.8 c / kWh +/- “consumption factor”. The consumption factor is calculated as follows:
consumption factor = (A-B) / E, where
- A is the sum of consumption * spot price over every hour of the month
- B is the total consumption * average price in Nordpool for the month
- E is the total consumption of the month
In other words, if I use power on hours which are cheaper than the month’s average spot price, the consumption factor will be negative and decrease the price that I pay of the whole month’s power. With these optimizations this means that the 14.8 c/kWh is effectively a ceiling price that I will have to pay under any circumstances, even if the Nordpool would be at 100c / kWh next winter.
Here’s a 7 day trend for the consumption factor. If I would be able to keep this trend, I would pay 14.8 - 5.9 c / kWh but it’s not going to be that much negative because the July 26-27 was so highly exceptional. But anyway, this I will have a double digit discount to the power bill, which is is quite nice 
