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Plug-In Solar Savings & Payback Calculator
Pick your state, kit size and where the panels will go. We fill in your state's average electricity price and sunlight — change any number to match your own bill.
Your plug-in solar savings
How this calculator works
- Yearly output = kit watts ÷ 1,000 × your state's peak sun hours × 365 × 0.80 (inverter, heat, wiring and dirt losses) × a placement factor × (1 − shade).
- Savings = yearly output × the share you use yourself × your electricity price. Power you don't use flows to the grid, and plug-in systems usually aren't paid for it.
- Payback counts each year's savings, with electricity prices rising by the percentage you choose and panels losing about 0.5% of output per year, until they add up to the kit price.
Placement factors are rules of thumb for the continental US, compared with a panel tilted about 30° toward the south: lying flat ≈ 88%, tilted east or west ≈ 85%, vertical on a south-facing railing ≈ 70%, vertical facing east or west ≈ 55%. For a precise estimate at your exact address and angle, NREL's free PVWatts calculator is the gold standard — enter its yearly kWh in the output assumptions here.
Example savings in states where plug-in solar is legal
Using each state's average residential price and sunlight, with 80% of the power used at home:
| State | Avg. home rate | 800 W on a south railing: yearly output | 800 W railing: yearly savings | 1,200 W tilted south: yearly savings |
|---|---|---|---|---|
| California | 33.2¢ | 916 kWh | $244 | $522 |
| Maine | 30.0¢ | 687 kWh | $165 | $353 |
| Connecticut | 28.0¢ | 687 kWh | $154 | $329 |
| New Hampshire | 26.8¢ | 687 kWh | $147 | $315 |
| New Jersey | 24.0¢ | 703 kWh | $135 | $289 |
| Vermont | 23.9¢ | 654 kWh | $125 | $269 |
| Maryland | 21.3¢ | 719 kWh | $123 | $263 |
| Colorado | 16.7¢ | 899 kWh | $120 | $258 |
| Virginia | 16.8¢ | 736 kWh | $99 | $212 |
| Utah | 13.2¢ | 899 kWh | $95 | $203 |
Electricity prices: EIA, residential average, January–July 2026. Sunlight: NREL data via Unbound Solar. Your utility rate and site will differ.
How to get the most from a plug-in kit
- Angle beats everything. If you can tilt panels toward the sun instead of hanging them flat, you can gain 30% or more.
- Avoid shade. Even partial shade on one panel can cut its output sharply.
- Use power at midday. Run the dishwasher, laundry or charging while the sun is up to raise the share you use yourself.
- Match the kit to your daytime use. A kit bigger than what your home uses during the day mostly sends unpaid power to the grid. Use the kit size calculator.
- Check your state's rules first. Limits, certification and notice requirements differ — see laws by state.
Frequently asked questions
How much can a plug-in solar panel save per year?
It depends mostly on your electricity price and placement. Using state averages, an 800 W kit hanging on a south-facing railing saves roughly $95–$165 a year in most states that allow plug-in solar and about $245 in California. A 1,200 W kit tilted toward the sun saves roughly $200–$350 a year in those states and over $500 in California.
How long does balcony solar take to pay back?
With state averages, an $800, 800 W kit on a south-facing railing pays back in about 3–4 years in California, around 5–6 years in states like Connecticut, New Jersey and Maryland, and 7–8 years or more where electricity is cheaper, like Utah or Virginia. Shade or east/west vertical mounting makes it longer. Enter your own kit price and rate for your number.
Do I get paid for extra power from a plug-in solar kit?
Usually not. Most plug-in solar laws exempt these small systems from net-metering, so power you don't use at the moment flows to the grid unpaid. That's why sizing the kit to your daytime use matters. Check your state's law and your utility.
Is it better to hang panels on a railing or tilt them?
Tilting panels toward the south produces the most. Panels hanging vertically on a south-facing railing typically make roughly 70% as much, and vertical east- or west-facing panels roughly 55%, though results vary with location and season.
Last updated October 6, 2026.