Prevailing wage and/or Davis-Bacon provisions relate to employers who land public contracts. That part of the question was a bit startling for this issue. Your client seems to be doing some deep diving without a scuba tank.

I think your client might have been reading something along these lines:

https://www.seia.org/initiatives/solar-investment-tax-credit-itc

And confused personal use with production. Unless the person is creating a solar or wind farm, they are not a producer for purposes of these provisions.