I think that is an unfounded assumption. It's hard to get an extra loan on top of a mortgage, even if you have a very good use for it. That's why passing the cost on through is not a neutral effect, but a helpful one.
Your argument is unfounded. There are plenty of solar power lenders willing to finance such purchases. Saying that passing the cost through a single larger loan makes it significantly easier to swallow is completely illogical and implies people don't like making/saving money.
I think that is an unfounded assumption. It's hard to get an extra loan on top of a mortgage, even if you have a very good use for it. That's why passing the cost on through is not a neutral effect, but a helpful one.