Mining equipment can also be older models no longer cost effective to mine with when you're paying for utility power.
A side effect of that is that if the grid is down, you're also required to shut down your solar system (which makes complete sense, it's a safety thing to not have power sources connected while there's work being done) except that you're apparently not allowed to disconnect.
Discussion on [1] notes that disconnectable systems can be quite a bit more expensive, but it sounds like that's not even a legal option - no connection, no occupancy.
[1] https://www.dailykos.com/stories/2017/9/18/1699490/-Solar-Po...
A more reasonable solution is to just sell that electricity than buy more reasonables. If you pull say a net 5% ROI you double energy produced every 15 years. With the added bonus of creating an income stream for retirement etc.
Edit: Not an outdoor setup but a setup to use all electricity surplus to regular needs for mining instead.