I think I have mentioned before that our apartment has solar cells, which I thought to be quite fancy. I’m sure most of you know how the system works, but let me just give a short overview.
The energy the solar cells generate, which is on average about 7 kw, is used whenever possible before energy is bought. I think the basic usage is about 0.2 kw/h, so as long as the same amount is produced they cancel each other out. On sunny days though there is a lot more produced than used at the given moment, in that case the surplus is sold back to Tepco. On rainy days, or especially during cooking, the usage exceeds the produced energy, so the rest of the needed energy is purchased from Tepco.
For the time we have lived here, the produced energy has every month surpassed the bought energy, though I think summer months with possibly heavy air conditioner usage will end this streak. I was quite sure that the energy that was sold back to the company would get a significantly lower price than the energy we buy. Turns out, that doesn’t seem to be the case. The bill for last month (it’s always mid-month to mid-month) came today and attached was the note for the surplus, which was a whopping 10.000 Yen (about 70 Euro)! Considering that the electricity bill for the last two months was half that, I am now more than before thankful for those solar cells (^_^)