I recently checked into it, the lease was for 20 years, at rate of 7.5%.
It would make more sense to simply get a HELOC at 3% and purchase the system or “prepay the lease”.
Also, the electric bill is tiered, 15-17 cents for the first 450 kwh, 27-29 cents for anything after that. The solar companies will always quote you a system that would cover the entire bill. You may want to get a system that simply cover your usage past the 450 kwh mark.