i know they use more, on a cloudy day in particular they probably use 90 or 95% net power from the grid. But if they are truly paying zero for their electric bill as you say, then they are getting 90% free power on those cloudy days. That is beyond ridiculous, it is criminal, mostly because I know the company that leases the systems is cleaning up on subsidies and profit.
My neighbor says he uses more power NET than he generates but BGE pays him $3K a year just for having solar panels.
Criminal??? Martin O Malley.