I received a 1099 from my solar installer....Is it taxable?

I'm helping a buddy of mine with his tax return on TurboTax.

 

He installed a rooftop solar system in 2023.  The State of Illinois offers an incentive called "Illinois Shines" where based on the size of they system, the State of Illinois gives money to the solar installer.  The solar installer then decides whether or not to pass that incentive to the homeowner, but from I understand most installers pass along 100% of the incentive to their homeowners.

 

Anyway, the solar installer mailed my buddy a 1099 for around $14,000, which is his share of the "Illinois Shines" incentive.  After having spend quite a bit of time reading about this, I'm almost certain this $14,000 is taxable income to the homeowner, even though it's a incentive (I'm thinking it's like a rebate?), but before we enter it as taxable income, just wanted to get the forum's opinion if somehow this isn't a taxable event.

 

Thanks!