288 prices from 365 days
Sweden has four price areas, SE1 in the north to SE4 in the south, and the day-ahead market sets a price per hour for each. We store every day's 24 hourly prices per area, fetched daily from elprisetjustnu.se, and for your area average each clock hour of each month over the last 365 days: 12 months × 24 hours = 288 values. The 17:00 price in January is the mean of every January 17:00 in the window; the 13:00 price in June is the mean of every June 13:00. Days with 23 or 25 hours at the clock change are skipped, and a month without one complete day falls back to flat monthly averages.
A month × hour price is the resolution the model can use: generation is one typical day per month and the battery is dispatched hour by hour, so a single day's price spike is averaged out by design.
What a kWh costs you at home
The spot price is what the supplier pays. An imported kWh costs you (spot + supplier markup + grid transfer fee + energy tax) × 1.25 for VAT. The defaults: a markup of 5 öre per kWh, the 2026 energy tax of 36 öre per kWh (lowered from 43.9 öre on 1 January 2026; parts of northern Sweden pay 9.6 öre less, which we do not model), and the transfer fee of the grid company you pick, for example Ellevio's 20.8 öre per kWh excl. VAT from its price list of 1 June 2026 for a 20 A fuse. Every number except VAT can be changed by hand in the Prices panel.
The fixed monthly fees of the supplier and the grid company are shown but cancel out of the saving: you pay them with or without solar.
Sold electricity earns the spot price
Solar you do not use goes to the grid and earns that hour's spot price, without VAT. The 60 öre per kWh tax credit for micro-producers ended on 1 January 2026, so it is not counted. If your supplier pays a fixed export price, type it and it replaces the spot export.
This asymmetry, buying at spot plus about 1 kr of fees and taxes but selling at bare spot, is why a kWh used at home is worth more than a kWh sold, and why a battery can pay for itself.
Effekttariff: a peak charge you enter yourself
Some grid companies bill a power charge in kr per kW on the month's highest hourly import. None of the grid companies in our list bills one to households as of 6 October 2026: Ellevio dropped its charge on 1 June 2026, Vattenfall Eldistribution runs a pilot of about 2 000 customers, and E.ON Energidistribution paused its planned introduction. So the charge applies only when you enter one.
When you do, the battery's peak-shaving strategy competes with the other three, and the month's peak is priced the way the engine counts it: the highest hourly import of the month, every hour counted, not only winter weekdays.
What this is not
The prices are the last 12 months, not a forecast: next year's spot price is unknown and the saving moves with it. We do not read your own bills or meter data, and we do not show several years of history. The energy chart on your result shows the 12 × 24 profile the simulation used, with its source named.
