power

Calculates solar system return on investment, payback period, and levelized cost of energy (LCOE). Models year-by-year savings accounting for panel degradation, utility rate inflation, federal Investment Tax Credit (ITC), state rebates, and annual maintenance. Outputs net cost after incentives, payback year, total lifetime savings, ROI percentage, and LCOE in cents/kWh. Essential for residential and commercial solar financial analysis, installer proposals, and comparing solar vs. grid economics over a 25-year system lifetime.

post/api/solar_roi

Request

  • Base URL: https://calc.engineer
  • URL: https://calc.engineer/api/solar_roi
  • Auth: none declared

Request body

system_cost_usdnumber required

Total installed system cost in USD

system_size_kwnumber required

System size in kilowatts (kW)

annual_production_kwhnumber required

Estimated annual energy production in kWh (from PVWatts or system_size_kw * peak_sun_hours * 365 * 0.80)

electricity_rate_centsnumber

Current electricity rate in cents per kWh, default 15

annual_rate_increase_pctnumber

Annual utility rate increase percentage, default 3%

federal_itc_pctnumber

Federal Investment Tax Credit percentage, default 30% (US ITC)

state_rebate_usdnumber

State or local rebate amount in USD, default 0

annual_degradation_pctnumber

Annual panel degradation rate, default 0.5% per year

annual_maintenance_usdnumber

Annual maintenance cost in USD, default $100

system_lifetime_yearsnumber

System lifetime in years, default 25

Response

Computed result for solar_roi

toolstring required
versionstring required
computed_atstring date-time required

Changes

No recorded changes to this operation across all 1 revision of this API.