What?

If the solar company does out of business, the borrower still has to make the loan payments for the remainder of the term because that loan was almost certainly sold. Meanwhile, the solar panels will still be producing energy, so the borrower isn't screwed out of the investment. The downside of the company going out of business though is that the warranty for the labor of the solar installation is no longer usable because there's no company to call when something breaks. Possibly, the borrower could call the solar panel or inverter manufacturer for a warranty claim, but that's not as easy as calling the installation company.

In any case, saying "screwed on your investment" is pretty far from the truth.