We also do a property orientation and show them how to operate the house, change filters and batteries, turn off water main - and of course the mystery of GFCI outlets

Quote from @Robert Jackson: How to finance your first spec build?

Once completed, the goal is to get them rented and then pull money out of each house to build a high performance spec.

I’d like to be protected if it takes longer than 60 days to sell a spec.

It would be a better investment to buy lithium or platinum, at least they have some uses in the battery and oil industries respectively; Gold has no use anywhere, it is just a shiny metal.

This is anecdotal, but I come across of ton of GCs looking for spec-build financing in local meetups and networking groups, such as on facebook on in person meetups. 

Quote from @Ian Porter: We just completed due diligence on a waterfront lot for our second spec build in North Ga.

Lots of 4x4 posts out there in the wild as well, but code now specs 6x6 in my area in most cases.

You could start by reaching out to any local corporations that do assisted living in your area and see what they are looking for (location, space specs, etc). 

They could buy just the battery and not the solar if their problem is really the power company turning off the juice.