NW, I will bite.
Your idea is good in theory, but not so much in practice. Too many people just do not rathole enough money for retirement, and wind up working much longer than they thought they would. They might even wind up owing more in tax if their federal and state combined rates are greater than the federal income tax credit. Some are going to screw up and withdraw too much from their IRA, so the penalty would still apply to the excess. Others will think that they can upgrade their panel or do other ancillary electrical work as part of the solar installation and then realize come tax time that the extra work performed would be ineligible, and a penalty would apply.
California has a 2 1/2% penalty on top of the federal 10%.
Many counties in California participate in the HERO program (at least as recently as 2016; I have not checked recently.) Under this program, homeowners can install solar panels on the home with zero down. The cost of the program is added to their annual real property taxes and paid off over twenty years at 2% interest. It is a separate line item from the property tax assessments, and can be paid off any time without penalty. It also carries over to a buyer should the original owner sell. Pretty sweet deal, if you ask me.
Finally, the Code is so cluttered with exceptions, exceptions to the exceptions, and non-exceptions that adding stuff like this to an already cluttered and Byzantine set of rules just makes everyone's life more difficult--both preparers and taxpayers who learn about tax law from internet fora, their bartender, or their brother-in-law's neighbor's cousin's hair dresser.
