Yeah, summarizing electricity cost with one number is not doable in countries where seasons vary as much as in Finland.

Electricity cost will always be higher during winter where it is needed for heating. And this is where households will also use more.

For heavy industry they are buying from themselves when the electricity prices spike (Pohjolan Voima). Basically they always get it at cost of production (mankala periaate).

This is why you don’t see upm kymmene, stora enso, kemira, etc profits go down when electricity prices are high (they go up as they can sell what they don’t need for massive profits). This mainly applies during "normal" times (when olkiluoto nuclear plants go down which they own a big chunk of or something like that the situation might change)