I have a large 20kw system for an old leaky farmhouse and it provides me about $6k in energy and credits a year. I like thinking about it as a near guaranteed,

I have a large 20kw system for an old leaky farmhouse and it provides me about $6k in energy and credits a year. I like thinking about it as a near guaranteed, medium return long term investment that's good for the environment. Each year is roughly 13% returns and I should get that for at least 20 years or so.