As I pointed out, it is "like" HELOC or Credit Card, as the person asking also stated it is not from Home equity. I was pointing out that the presence of a Lien doesn't have to relate to anything that counts as deductible or even as debt. A lien is a process. It's a way to flag the property, such as a Lawyer wants to place a lien on my house against a contingency lawsuit. In that example, there is no debt, no loan, and no interest. It's a fallback provision. It's like a co-signer, not the borrower.

It is typical for the financing to be part of the retail package offered by the installers who are also offering ridiculous statements regarding rebates and tax "refunds" to the customers. This would be Solar Interest. It's the same as if you put it on a credit card, because it is Vendor Cardless Lending, really. It's like buying a roof and agreeing to pay over time.

If it is a HELOC, that follows the tracing rules, that the funds were used for improvement to the house leveraged. The solar cost falls under the energy credit provision. The Interest, in this example, falls under the Mortgage provision. It's not Solar Interest, in this example.