It is a cost for society at large. Any workers that are employed in solar are not employed in some other job, so we have to be losing out in production somewher

It is a cost for society at large. Any workers that are employed in solar are not employed in some other job, so we have to be losing out in production somewhere if we switch our power generation from something that requires fewer workers to something that requires more. Even if the extra workers required to make solar work came exclusively from the ranks of the unemployed or retired, we are still losing the leisure time they had previously been enjoying, which is a production of sorts.