Not sure if this applies to commercial buildings as well, but for homes, you get paid a pittance for feed-in tariffs. It used to be lucrative and early residential adopters got great rates locked in presumably for life but anyone since faces tariffs that get reduced and reduced.

One hassle for those with the early tariffs is that they can't scale up their systems without revising the contract and losing their rates. Many early adopters were putting on 1-3kW systems (probably because panels were more expensive or they were not completely confident about the technology) when you'd probably put on 5-10kW now.