ClueLuma

Solar capital and simple payback (SPP) calculator

Use realistic annual savings rather than peak irradiance times every hour.

Units
SPP=A×careaSyear\mathrm{SPP} = \frac{A \times c_{\text{area}}}{S_{\text{year}}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

ft²
$/ft²
$/yr
yr

Worked example

Given

  • AA = 360 ft²
  • careac_{\text{area}} = 74 $/ft²
  • SyearS_{\text{year}} = 3,800 $/yr
SPP=360×743800≈7.011\mathrm{SPP} = \frac{360 \times 74}{3800} \approx 7.011

Symbols and units

SymbolMeaningUnit
SPP\mathrm{SPP}simple paybackyr
AAcollector areaft²
careac_{\text{area}}installed cost per area$/ft²
SyearS_{\text{year}}net annual savings$/yr

Related calculators

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.