Took a look its configuration once again and came to conclusion that I can't use it because here in Estonia our grid service has two tariffs, day and night/weekend - which is half the cost of day tariff.
Given that half of my bill is grid service fees (it's actually more complex than just kw * tariff), I can't ignore it. But I can't configure it either to DESS.
So is that even planned to be supported in those formulas, or even presets?