Solar financing — loan vs lease vs PPA vs cash

The four financing paths

Cash: pay $20,000-$30,000 upfront. Claim 30% federal credit ($6,000-$9,000). Net cost $14,000-$21,000. Highest 25-year savings: $30,000-$60,000.

Solar loan: 5-25 year term, 5-9% APR in 2026. Owner claims the federal credit. Most loans have a re-amortization clause: pay down principal with the credit refund or payment jumps. Total interest: $5,000-$15,000.

Lease: installer owns the system. Homeowner pays a fixed monthly lease, escalating 1-3%/year, for 20-25 years. Total savings: 10-25% of utility-rate cost. No federal credit.

PPA (power purchase agreement): installer owns the system, sells the electricity to the homeowner per kWh produced (e.g., $0.15/kWh, escalating 2.9%/year). No federal credit. Similar economics to lease.

When each makes sense

Cash: best for owners with $20K+ liquid, plans to stay 5+ years, and federal tax liability of $6,000+ in year one. Returns 10-15% IRR after the credit — beats most CDs and stocks for risk-adjusted return.

Loan: same long-term economics as cash if rates are reasonable. Owner keeps the credit. Risk: re-amortization clauses reset payment if you do not apply the tax credit refund to principal in year 2.

Lease/PPA: best for owners with no tax liability (retirees, low-income), or those unwilling to commit capital. Beware long-term escalators that erode savings; some leases hit 2.9%/year while utility rates only rise 1.5-2%.

How to verify the math before you sign

Get every contract in writing and read the fine print on escalators (in lease and PPA terms), prepayment penalties (in solar loans), production guarantees (every contract type), and end-of-term options (lease and PPA: buy-out, remove, or extend). The single most common cause of regret on a solar install is signing a lease with a 2.9 percent annual escalator while expecting electricity rates to rise faster — they often do not.

Ask each installer for a written side-by-side comparison: cash vs loan vs lease over 25 years, with utility rate inflation modeled conservatively at 2 to 3 percent per year. Reputable installers (Sunrun, SunPower, the EnergySage marketplace, and most regional independents) provide this in writing as a standard part of the proposal. If an installer refuses or hand-waves the math, treat that as a flag.

For cash and loan financing the federal credit is claimed on IRS Form 5695 in the tax year the system is placed in service. Carry-forward applies if your tax liability is too small to absorb the full credit in year one. The avoiding-the-renewal-trap guide covers escalator math in the supplier-contract context, and the exact same logic applies to lease and PPA escalators — small annual increases compound dramatically over 20 to 25 years.

The 25-year tradeoffs that change the answer

Cash maximizes ownership upside. After payback (typically year 7 to 12), every kWh produced is effectively free for the remaining 13 to 18 years of system life. On a typical 8 kW system that is 10,000 to 13,000 kWh per year of free electricity for the back two-thirds of the contract — easily $1,500 to $3,000 of annual avoided utility cost in inflation-adjusted dollars.

A loan lets you keep the cash on hand for other uses (home renovation, retirement contributions, college funding) while still capturing the federal credit and ownership economics. The catch is interest cost — a 6 percent 20-year solar loan adds roughly $7,000 to $12,000 of total interest on a $25,000 system. Re-amortization clauses are common: if you do not apply the year-two federal credit refund to principal, the monthly payment jumps. Read those terms carefully.

Lease and PPA contracts essentially turn solar into a discount on your electric bill rather than an investment. The discount is real (typically 10 to 25 percent versus the utility rate in year one) but the upside is capped by the escalator. Over 25 years, a lease typically delivers 30 to 50 percent of the lifetime savings of an owned system. The right framing is "small monthly discount, no upfront cost, no upside" rather than "cheap solar."

Resale impact is the underrated factor. Cash and loan-owned systems transfer cleanly — the system is part of the home and the new buyer inherits the production. Leased systems require the buyer to assume the lease, and a meaningful share of buyers (perhaps 15 to 30 percent in active markets) refuse to take on a long-term solar lease. That can complicate a future home sale or force you to buy out the lease at sale time.