Solar payback and ROI
Compare cash and financing-adjusted solar payback.
Updated 2026-07-17 · Formula version appears with every result.
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Data confidence
Early estimate
Evidence used
Uses installed cost, expected savings, financing, maintenance, escalation, and degradation.
What can vary
Actual production, tariff changes, financing terms, replacements, and downtime affect payback.
Planning use
Educational estimate only. Confirm the final design and quotation with qualified professionals.
How this estimate works
Calculations are versioned, reviewed, and reproducible. Inputs are validated and planning ranges are used instead of false precision.
Results support early decisions. Confirm utility rates, equipment specifications, site conditions, and professional requirements before committing money. Review the methodology and source policy before treating any estimate as decision-ready.
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Before using the calculator
What this calculator estimates
Compare simple payback and financing-adjusted cash flow from project cost, expected savings, maintenance, rate, and term.
Who it is for
Buyers comparing cash and financing scenarios without treating a simple payback figure as a complete investment decision.
Inputs and methodology
Simple payback divides installed cost by annual savings net of entered maintenance. Financing scenarios add the entered financing rate and term to show how borrowing changes total cash outflow and recovery.
Required inputs
- Installed project cost
- Expected annual savings and maintenance
- Financing rate and term when applicable
Philippine planning assumptions
- Annual savings are treated as an estimate, not a guaranteed cash flow.
- Taxes, insurance, replacement timing, opportunity cost, and detailed loan fees may require separate analysis.
Worked example
A ₱350,000 project with ₱65,000 expected annual savings and ₱3,500 maintenance has about ₱61,500 net annual benefit before financing. Simple payback is roughly 5.7 years, subject to the assumptions.
How to interpret the result
Compare the result with the expected ownership period, financing obligations, replacement risks, and conservative savings. A shorter result is not automatically a better proposal if scope or quality differs.
Use the result as a comparison baseline: change one assumption at a time, keep the original inputs, and ask installers to explain why their written estimate differs.
Common mistakes
- Using gross savings without maintenance
- Ignoring financing fees and replacement risk
Related questions
Is payback the same as ROI?
No. Payback measures time to recover an outlay. ROI compares gain with investment over a defined period and can require more complete cash-flow assumptions.
What should be included in annual net benefit?
Use conservative avoided electricity purchases, then subtract recurring maintenance, financing costs, expected replacement reserves, and other known operating expenses.
Limitations and disclaimer
- The result is an educational planning estimate, not a quotation, site survey, electrical design, or engineering approval.
- Verify current rates, equipment, roof conditions, utility rules, and written installer assumptions before spending.
Last reviewed 2026-07-20