In my native Netherlands, in the summertime there's solar, in winter there's is wind.

I have a dynamic energy contract, I pay spot prices + taxes and markup. What solar energy I sell in the summer, I can buy in the winter. With our heat pump, I need to generate about twice as much as I did before we had the heat pump, to match it in money (summer is cheaper than winter at the moment). Watt for watt is not a useful measurement IMO, since I can't store Watts, but I can store euros.