“A Low APR Means a Cheap Loan”
You'll see them everywhere — “as low as 1.99% APR,” promotional rates in the low single digits, sometimes a “0% intro” teaser period — paired with the headline monthly payment number. The implicit argument: a low interest rate makes financed solar essentially as cheap as paying cash, with the convenience of a monthly bill instead of a lump sum.
The APR is real. It's just being applied to the wrong number.
Solar loan products are built on a structural fee that almost never gets itemized to the customer: the dealer fee. The financier charges the installer a fee for originating each loan — typically 15% to 30% of the project price, with the 2026 industry average sitting at roughly 22%. The lowest-APR products carry the largest dealer fees, sometimes pushing past 40%. The installer doesn't eat that cost. They roll it into the system price the homeowner finances.
There's an industry term for what happens next: grossing up. The installer absorbs the dealer fee on paper, then grosses up the system price — marks it up enough that, after the financier nets out the fee, the installer still receives their installation revenue. The number on your proposal as “cash price” is already the grossed-up number. The financed principal is the same number. The lower the advertised APR, the larger the gross-up, and the larger the gap between the price you're seeing and the true installed cost.
Across the broader 2026 marketplace, the median quoted rate on residential solar loans is in the 6-8% range on a 25-year term — well above the “as low as 1.99%” floor. The low promotional rates exist; they come bundled with the largest dealer fees. The two move together by design.
Run the absolute totals, not the rate. The total interest paid over a 25-year solar loan at a low headline APR, on top of a principal that includes the dealer fee, often exceeds what a cash purchase at a much higher imputed rate would cost over the same horizon. The headline number is doing work the underlying math isn't.
A few more structural points worth knowing before you sign a solar loan:
25-year terms outlast inverter life. Most residential inverters are warranted 10-25 years and start failing somewhere in that window. A 25-year loan can have you paying down financing for equipment you've already had to repair or replace.
Legacy re-amortization clauses are now a trap. Many solar loans written in 2022-2025 included a clause: if the borrower didn't apply the federal residential tax credit to principal within roughly 18 months, the monthly payment would jump on re-amortization. That structure was built around the residential 25D credit, which ended December 31, 2025. New installs financed under legacy paperwork can face the payment jump with no credit to offset it. Read the re-amortization clause carefully on anything that originated before 2026.
Prepayment penalties exist on some products. Not all — many solar loans are penalty-free on early payoff, which is genuinely useful. But check the document. A loan with a prepayment penalty removes the customer's best lever for converting bad financing math into something closer to cash-purchase math.
A UCC-1 lien attaches to the system (sometimes the home). Standard practice — the financier's collateral. Shows up in title work and can complicate refinancing or resale until the loan is paid off.
When financing solar actually is the right call
Financing solar is a legitimate choice for plenty of households:
You want to preserve your liquidity for other purposes. Business capital, emergency reserve, college savings, other investments. Concentrating cash in a roof-mounted asset isn't the right move for every balance sheet, and a financed system with a fully understood dealer-fee cost can be the right trade — as long as you understand you're paying for that liquidity preservation.
You plan to pay the loan down aggressively. A penalty-free loan paid off in 5-7 years instead of 25 converts most of the bad financing math into something close to cash-purchase economics. The dealer fee's still baked into the principal, but you avoid the bulk of the long-tail interest cost.
You prefer a managed monthly line over a lump-sum decision. Some households operate on monthly cash flow, not balance-sheet allocation. A solar loan that offsets a utility bill and runs as a known monthly line — at a cost you've consciously sized — is a real budgeting structure, not a worse-than-cash compromise.
The question to ask any installer who quotes you a financed system is the one their proposal is usually structured not to surface: what does this system cost before the gross-up, and how much of the financed principal is the dealer fee?