We got a really good mortgage rate on one of them so there is actually some cash flow on that.

The suits have around 40% chance of eventually collecting, we've used collection agencies before and their success rate was around 15%.

The second unit has been a rental with ~the same occupancy but they were charging lower rates.  

There's no seasoning period for a rate-term refi. 

How can I determine an appropriate cap rate for this?

The US real estate economy in general has boomed thanks to COVID and previous rate drops.

We had the seller cover all closing costs, pushed out closing 60 days, and were able to use that to cover all closing costs and do a rate buy down for a year.

The kicker is my interest rate is 3% on both. 

I can only get funds from my Heloc with 9.72% rate.

If you are in a heavy sun, high cost of electricity and high rate of usage market, and you buy the panels, and you can resell to the provider rather than maintain your own batteries, you probably will make money especially if you hold long enough.