First of all, thanks for the mod: it's so useful!
Second, I have some ideas for higher tier buildings:
1) a power plant with "glass cover" that allow the use of solar panel inside; maybe the cover can transmit only 80% (or whatever percentage) of solar radiation inside, reducing the solar panels efficiency;
2) factory buildings with pollution filters that can reduces outgoing pollution;
3) a building for storing energy in accumulators (I know that you are having problems with energy looping and so on, but I would really like such a building) where energy can go both directions, but there isn't the possibility to move anything else (neither solids or liquids).
Of course these ideas are for the mid-late game (especially the first 2), so I would expect some high-end material in the receipt.

Thanks again and keep going!

Jacopo