Tax Credit Question

I've been reading other posts about this topic (federal tax credit), and it appears that this not a rebate and only really helps you if you owe in taxes at the end of the year. If that is accurate, wouldn't it make sense to have fewer taxes withheld from one's paycheck (bigger paychecks) during the year, and then when taxes are due, use the credit against that? Our installer suggested a sizable credit as the whole install (GAF solar shingles) could be written off, and based on how much taxes we are likely to owe, we'd need ~5 years of rollovers to get the full 30% back and the rollover can only be done for 4 years.

If my suggestion is viable, why wouldn't someone be doing this? You'd get more money in your pocket during the year, and the credit would effectively handle the taxes that weren't withheld from one's paychecks.

Does that make sense, and if so, has anyone else done this in order to amplify the usefulness of the credit for a given year?