Solar
Solar Lease vs Buy Calculator
Lease-versus-buy compares nominal cash, loan, lease, PPA, and utility-baseline payments over 25 years. It is a scenario comparison, not a contract recommendation.
Compare nominal 25-year cash, loan, lease, PPA, and utility-baseline payments from visible user assumptions.
Calculated result
Ownership comparison
Calculating…
Calculated locally in your browser
Planning math only. Verify equipment specifications and installation requirements separately.
Data provenance: NLR PVWatts v8 grid awaiting its first private-key refresh; the visible peak-sun-hours fallback is active. EIA residential state averages updated 2026-08-13. ZIP centroids use the 2025 Census Gazetteer. No ZIP or calculator input is sent to those sources. Read the solar data provenance and limitations.
What this calculator returns
The lowest nominal total is not automatically the best contract. Compare ownership, transfer, buyout, production guarantee, maintenance, roof work, insurance, and early-termination terms.
Formula and variables
The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.
Cash is the entered cost; loan is total amortized payments; lease and PPA totals sum each year's payment after the entered escalator; utility baseline sums the entered annual energy at the changing utility rate.
- P
- Cash price or financed principal, as identified by the input.
- r
- Entered monthly interest rate derived from APR.
- n
- Number of scheduled monthly payments.
- g
- Entered annual lease, PPA, or utility escalation rate.
- E
- Entered annual solar energy used only in the PPA and utility scenarios.
All costs and escalation rates are user-entered. The comparison period is 25 years and values are nominal, not discounted.
Worked example
| Input | Value |
|---|---|
| Cash system cost | 20000 $ |
| Loan APR | 6 % |
| Loan term | 10 years |
| Starting lease payment | 120 $/month |
The default scenario compares a $20,000 cash purchase with a 10-year loan, a $120/month starting lease, and a $0.12/kWh starting PPA over 25 years.
Reference table
| Term | Calculator treatment | Verify in documents |
|---|---|---|
| APR | User entered | Truth-in-lending disclosure |
| Dealer fee | Added to financed principal | Cash price versus financed price |
| Escalator | Compounds annually | Lease or PPA contract |
| Principal lump sum | Zero by default | Eligibility and lender recast terms |
Frequently asked questions
How is a PPA different from a lease in this comparison?
The PPA scenario charges per entered kWh, while the lease scenario begins with a monthly payment; each uses its entered escalator.
Are the 25-year totals discounted to present value?
No. The page compares nominal totals and does not perform net-present-value analysis.
Does the lowest total identify the best contract?
No. Contract risk, ownership, transfer, roof work, production, service, and buyout terms can matter more than the nominal total.
Assumptions and limitations
- Not financial, tax, legal, or investment advice.
- Nominal totals are not net-present-value analysis and exclude tax effects, residual value, maintenance, and production variation.
- Use actual contract disclosures and qualified advice before signing.
- Assumptions reviewed 2026-08-13.
Method and sources
Review the solar data sources, calculation methodology, and electrical formulas for the references most relevant to this calculation. The broader technical sources index records source scope and verification. Last reviewed .