Wind and solar have high capital costs and low operating costs(wind and sun are free, except there is a small royalty or rent to the land owner).
Coal and natural gas have a lower capital cost but higher operating cost because they have to buy the coal and natural gas.
The pollution tax credit that the feds hand out to wind/solar is timed to the depreciation schedule of the equipment to offset the higher capital cost.
It is very common for govts to give tax breaks for capital manufacturing equipment, pollution control equipment, or ag equipment. In most states these type things are not subject to sales or use taxes.