Solar
Plug-In Solar Savings Calculator
Plug-in solar saves money when its output replaces electricity you would otherwise buy. This calculator separates self-used energy from surplus, which may earn nothing. Use local NLR PVWatts yield for this editable annual scenario, not a location forecast. No tax credit is included.
Estimate balcony and plug-in solar savings from panel power, local yield, shade, self-consumption, electricity rates, and upfront cost with no tax credit.
Calculated result
Estimated annual energy value
Calculating…
Calculated locally in your browser
Planning math only. Verify equipment specifications and installation requirements separately.
What this calculator returns
Start with the annual savings, then check the self-used and surplus energy. Try 30%, 70%, and 100% self-consumption to see how much the timing of your electricity use matters. A small kit can have a poor payback even when the panels produce well.
Before buying a balcony solar kit
A savings estimate is only one part of the decision. Check the actual installation and agreement before spending money.
- Check daytime use
- Compare generation hours with interval meter data. Do not assume evening demand can absorb midday solar without storage.
- Model the actual mounting
- A vertical railing is not a south-facing tilted roof. Use local yield for the real tilt and direction, then avoid counting those losses twice.
- Confirm permissions and equipment
- Ask the utility, relevant authority, and property owner about your exact system. This tool does not authorize a plug, outlet connection, export, railing mount, or DIY installation.
Formula and variables
The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.
Annual kWh = min(panel W, inverter W) ÷ 1,000 × annual AC yield × mounting retention × (1 − additional shade loss). Annual value = self-used kWh × import rate + surplus kWh × export rate. Simple payback = upfront cost ÷ annual value.
- Self-consumption
- The share of modeled generation used at home while available, not the share of your annual bill covered.
- Surplus
- Generation not used at home. It earns only the export credit you enter.
- Simple payback
- Upfront cost divided by first-year energy value, without financing, degradation, repairs, incentives, or discounting.
Percent inputs are divided by 100. Yield is annual AC energy per kW before the extra mounting and shade adjustments. The smaller-rating shortcut does not predict hourly clipping or weather.
Worked example
| Input | Value |
|---|---|
| Total panel rating | 800 W DC |
| Inverter output limit | 800 W AC |
| Annual AC yield per kW | 1200 kWh/kW/year |
| Generation used at home | 70 % |
With 800 W of panels and inverter capacity, 1,200 kWh/kW/year, 100% mounting retention, and 10% extra shade, generation is 864 kWh/year. At 70% self-consumption, 604.8 kWh replaces purchases. At $0.18/kWh and no export credit, annual value is $108.86. A $1,000 cost gives about 9.2 years of simple payback.
Reference table
| Used at home | Self-used energy | Annual value | Simple payback |
|---|---|---|---|
| 30% | 259.2 kWh | $46.66 | 21.4 years |
| 70% | 604.8 kWh | $108.86 | 9.2 years |
| 100% | 864.0 kWh | $155.52 | 6.4 years |
Frequently asked questions
Is balcony solar the same as plug-in solar?
The terms can overlap, but balcony describes a mounting location and plug-in describes a connection approach. This tool compares energy value for small solar systems, not whether a connection is permitted.
Will I save the full retail rate on every solar kWh?
Not necessarily. Only generation that replaces a purchase receives your avoided import rate here. Surplus receives the separate export rate, which defaults to zero.
How do I model vertical balcony panels?
Use an annual yield modeled for your location, tilt, and direction, with mounting retention at 100%. Alternatively, enter a supported retention adjustment to a reference yield. Do not apply both adjustments for the same loss.
Can I include a federal residential solar tax credit?
This calculator applies no tax credit. The IRS says the residential clean-energy credit is unavailable for property placed in service after December 31, 2025. Check current official rules and your own situation before relying on any incentive.
Assumptions and limitations
- Annual planning scenario only; not an hourly production, shade, clipping, or self-consumption simulation.
- When panel power exceeds inverter power, the smaller-rating shortcut can understate production. Use a proper hourly model for equipment selection.
- No storage, time-of-use schedule, degradation, financing, maintenance, tax credit, or fixed utility charge is modeled.
- No universal plug-in solar legality or installation approval is implied. Equipment, utility, local, lease, structural, and electrical requirements need separate verification.
Method and sources
Review the solar data sources, calculation methodology, and electrical formulas for the references most relevant to this calculation. The broader technical sources index records source scope and provenance. Content release .
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