Utilities · Efficiency
Solar ROI
Estimate solar net cost, year-1 savings, payback timing, and horizon savings under utility-rate assumptions.
Last reviewed: February 18, 2026
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What this calculator does
Estimate solar net cost, year-1 savings, payback timing, and horizon savings under utility-rate assumptions.
How it's calculated
- Inputs are validated before running the calculator-specific compute() function.
- Core math is deterministic and implemented in src/lib/calculators/solar-roi.ts.
- Results are recalculated instantly as values change and are shareable via query parameters.
- Disclosure assumptions and limitations are shown on-page for decision context.
Example
Example scenario: System cost = 28000 USD; Incentives = 30 %; Yearly kWh offset = 9000 kWh; Electric rate per kWh = 0.24 USD. Sample output: Net system cost after incentives: $19,600.00
Common mistakes
- Using optimistic rates or appreciation assumptions without testing a conservative case.
- Ignoring taxes, insurance, HOA, or maintenance in monthly cost planning.
- Treating modeled outputs as guaranteed quotes rather than planning estimates.
- Not comparing at least two scenarios before making a financing decision.
- Skipping professional review for legal, tax, underwriting, or insurance details.
FAQs
Does this include panel degradation?
No. This model keeps yearly offset constant for simplicity unless you adjust assumptions manually.
Are utility credits guaranteed?
No. Net metering and export-credit policies differ by utility and can change over time.
Can maintenance be zero?
Yes, but including periodic maintenance or inverter replacement assumptions can improve realism.
Is payback the same as ROI?
Not exactly. Payback is timing; ROI also depends on total net benefit over your holding period.
Should I rely on this alone for purchase decisions?
No. Validate with installer proposals, financing terms, and utility tariff documentation.