Did they get a 1099 or any other statement indicating that there is TAXABLE income?

With the little information provided I will reference what we have/had in my state where power companies were required to purchase excess residential solar power from a qualified homeowner's system. 

Never thought about this before, but I have not seen anyone report the payment from that - it just went to paying down the loan they took out to install the solar.

not sure if that helps at all.