Renting out ADU and main house with single solar system

[Gary Rodgers]

I'm working on building an ADU right now, just submitted plans yesterday. The building laws require that we have solar. Where I'm at in California I can install the solar now on the primary house before NEM 3.0 goes into effect (basically a terrible agreement between solar owners and their utilities) I'm looking at a 10kW - 11kW system to handle both buildings.

I will rent out the new ADU. One day I will rent out both individually and purchase another home. How would you handle the electric bill if someone went over? I can meter the ADU and subtract and know who used what but it seems like a lot to go through. What would your concerns and possible solutions to those concerns be?

I'm caught in an analysis paralysis but I see solar as a definite right now because I know that with an additional household our shared electric bill will be put into a very high tier and would far exceed the $180/month financed price. We are at about $280 a month as it is.