I’d love to know how you get on with using the salvage batteries. I’ve been thinking about doing such a project myself.You're right; but I've got the batteries anyway. I'm just transferring them from my work system to my home system. I am going to upgrade the 65kw work system with about 200kw of lithium batteries from salvage Tesla vehicles as a fun project.
I would expect that there will be a couple of months in winter where the extra capacity won't be used at home. However over summer it will really pay dividends as we currently send too much back to the grid.
Correct again on the shading of the windows. In this case aesthetics win out over energy efficiency as it would not work with the design of our house. I really was surprised at the gain we got from the tinting though, I expected a couple of % at best.