That makes sense. Can’t you give PSE a call and see what the schedule is?
Otherwise you could check what the cash price is anyway, and use a HELOC or personal loan to get a fixed interest rate (this really only makes sense if you’re serious about paying it off quickly)
But seriously ask about the “cash price”. Because I was shocked at how much more the principle is on the financing offered through the Solar company. It seems solar companies are partnered with financing companies to make the monthly price palatable for larger groups of customers.