PLUGWATTS — SMALL SOLAR VALUE WORKSHEET
Reviewed September 15, 2026. Keep this file privately.
Guide: https://plugwatts.com/is-plug-in-solar-worth-it/

This is a preparation worksheet, not a product quote or savings guarantee.
No-battery model. Complete every input with its source; leave unknowns unknown.

Equipment/configuration: ______________________
Quoted complete upfront cost C ($): ___________
Includes panels, inverter, mounts, cables, taxes, delivery, required work? ______
Quote date / source: __________________________
Annual AC generation G (kWh): _________________
Estimation source, location, orientation, shading and losses: ________________
Self-consumed share S (0 to 1): ________________
Evidence for timing/household demand: __________
Avoided variable electricity rate R ($/kWh): ___
Tariff/source/date: ___________________________
Annual confirmed export credit E ($): _________
Utility confirmation of export/meter handling: _____________________________
Annual costs A ($): ___________________________

Annual net value V = G x S x R + E - A
Simple payback = C / V only when V > 0.
If V <= 0: no positive simple payback under these assumptions.
For time-varying rates, calculate energy value by time period.
Never treat fixed charges as eliminated. Unknown export handling needs resolution.

Sensitivity: repeat with lower generation, lower S, lower R and higher costs.
Expected years of use: ____  Relocation/replacement uncertainty: _____________
Financing, degradation, discounting and price changes: not represented by this
simple formula. A payback period does not predict equipment lifetime.

Illustrative checks (not forecasts):
G=1000, S=0.8, R=0.20, E=0, A=0, C=1000 => V=$160, 6.25 years.
G=1000, S=0.4, R=0.20, E=0, A=0, C=1000 => V=$80, 12.5 years.
G=1000, S=0.8, R=0.20, E=0, A=0, C=1800 => V=$160, 11.25 years.