Solar and battery payback without tax credit

Estimate the first-year benefit and simple payback of a quoted solar and battery system. Enter annual solar generation and the home's total annual electricity demand from matching records or an installer report. These totals set limits; they do not prove that solar and household use occur at the same time.

Enter solar used directly by the home, excluding energy sent through the battery. Then enter battery electricity delivered to the home after losses, from solar charging only. Round-trip efficiency is the share of charging energy returned for use, including battery and inverter losses.

Use your avoided import price and actual export credit. Add the combined installed price, a confirmed non-federal rebate and extra yearly maintenance. The result shows remaining exports, grid purchases avoided and the first year's net system benefit. It also separates the battery's added benefit from the full system benefit.

Battery charging = delivered energy ÷ round-trip efficiency. Remaining exports = generation − direct consumption − charging. First-year benefit = (direct use + battery delivery) × import price + remaining exports × export price − extra maintenance. Payback = actual net quote ÷ positive benefit.

Convert efficiency to a fraction once: 90% means 0.90. Battery charging is larger than delivered energy when there are losses. Direct use plus battery charging cannot exceed solar generation. Direct use plus battery delivery also cannot exceed the entered household demand; both limits must be met.

Prices in cents per kWh are divided by 100 to obtain dollars. Solar used at home avoids imports but also reduces energy available for export. The battery's added benefit therefore accounts for export income given up on its charging energy. The net quote subtracts the confirmed rebate once; do not count a discount twice.

These illustrative inputs are separate from your saved answers. Prices, use and performance are held constant for this worked scenario; they are not personal defaults.

Use an installer model or monitoring records that support direct use and battery delivery at the times energy is available. Annual totals alone cannot test the operating schedule. Battery capacity in kWh is stored energy, not yearly delivery. Leave grid-charged delivery out of this solar-only energy balance.

Simple payback divides the net quote by positive first-year benefit. Zero or negative benefit has no finite payback. The estimate holds output, use and prices constant. It excludes borrowing costs, future price changes, equipment wear, replacement and the time value of money.

Existing electricity account fees remain outside the comparison. The calculation does not model backup service or power limits. Examples are not personal defaults, and missing fields do not silently become zero. An incomplete edit preserves the last valid result with a warning so it is clear which inputs produced it.

The published electricity option uses EIA state residential averages for July 2026, released on 24 September 2026 and checked on 14 October 2026. These describe past average prices. They are not your supplier's offer or a promise of future prices. Choose your bill price for a personal comparison. Include the taxes and usage charges that change with consumption; keep fixed account charges separate.

No federal 25D credit is included for equipment placed in service after 31 December 2025. Enter only a separately confirmed non-federal rebate. Use the export terms offered by your own utility or supplier; a published retail electricity average is not an export price.

Ask a qualified solar installer to check roof conditions, expected generation and how household use matches solar output. Ask for battery losses and delivered energy to be shown separately in the quote's supporting model.

Confirm installation, maintenance, replacement and export arrangements before buying. Check rebate terms in writing. The calculator cannot confirm safe installation, incentive eligibility or the battery's ability to supply selected appliances during an outage. Simple payback is one part of the decision, not a guarantee of savings.