Savings calculator
What would plug-in solar save you?
Pick your state, describe your balcony, and see annual savings, payback and lifetime value — using real electricity prices and honest assumptions.
Estimated savings · California
$378/ year
≈ $31.51 per month
- Payback
- 2.4 yrs
- Energy used
- 1,125 kWh/yr
- 25-year net
- $8,553
- CO₂ avoided
- 911 lb/yr
Monthly savings profile
Estimates only. Rate: EIA July 2026 state average; sun hours: long-term averages. See our methodology.
How we calculate
Production = system watts × peak sun hours × 365 × orientation factor × mounting factor × 0.86 system efficiency.
Savings = production × share used at home × your electricity rate. Exported surplus is valued at zero because plug-in systems aren't net-metered.
| Orientation | Factor |
|---|---|
| South | 1 |
| South-east | 0.95 |
| South-west | 0.95 |
| East | 0.82 |
| West | 0.82 |
| North | 0.58 |
| Mounting | Factor |
|---|---|
| Tilted ~30° (stand or ground) | 1 |
| Flat (0–10°) | 0.88 |
| Vertical (balcony railing) | 0.7 |
Full assumptions and sources are on our methodology page.
Calculator FAQ
How accurate is this calculator?
It's a planning estimate, typically within ±20% for a well-placed system. It uses each state's average residential electricity price (EIA, July 2026) and long-term average sun hours. Shading, local weather, your exact tariff and how much of the output you actually use at home all move the real number.
Why does 'share of output used at home' matter so much?
Plug-in solar laws exempt small systems from net metering, so electricity you push back to the grid earns nothing. Only the energy your home consumes while the sun shines saves money. Fridges, routers, freezers and anything running during the day soak up production; a small battery raises the share to 95% or more.
Should I buy an 800 W or a 1,200 W kit?
Size to your daytime base load. If your home draws 200–400 W most of the day, an 800 W kit will be almost fully used. A 1,200 W kit makes sense for larger households, homes that work from home, or if you add a battery.