Great question. I have only sold homes that have "owned" systems. I have to be honest with you:(and I am in the land of nature loving tree hugger) a solar system is nice, but in a high dollar market, it is not going to make that much difference when attracting a buyer. I own a system on ,y personal home and I sing its praises, but a 20K-30K system does not get you the same return as that same money put in a remodeled kitchen - just say'n.
We did not "lease" for the issues of maintenance, ambiguous repair and insurance loss issues and my guess is that it would be a complication to have a lease that must be assumed on a system. If you are doing it for yourself and are not planning on selling - go for it. If you want to sell down the line, buy the system and finance it if you must. My opinion for what it is worth!