Plug-in solar savings calculator for PG&E, SCE and SDG&E

Over the years

What the kit could save over its life if electricity prices keep changing. These are projections, not promises; try the settings.

Net savings after 10 years

$2,609

Net savings after 20 years

$7,222

Payback

3.0 years

Yearly return (IRR)

34.6%

Value today (NPV at 4.94%)

$3,952

Savings minus the kit price, year by year

Sources: Price change: EIA: Electric Power Annual Table 2.10, average price by state, 2025 and 2024 (opens in a new tab) · Lifetime: CraftStrom: warranties (20-year panel product warranty, 80% output after 20 years) (opens in a new tab) · Panel output loss: NREL: Photovoltaic Degradation Rates, an Analytical Review (Jordan and Kurtz, 2012) (opens in a new tab) · Discount rate (Oct 30, 2026): U.S. Treasury: Daily Treasury Par Yield Curve Rates, October 2026 (opens in a new tab) · Battery efficiency: NREL: Cost Projections for Utility-Scale Battery Storage, 2025 Update (85% round-trip efficiency) (opens in a new tab) · PG&E time-of-use rates: PG&E: Schedule E-TOU-C tariff (opens in a new tab). Projections, not promises. Not financial advice.

How we calculated this

• PG&E E-1 rate: 40.7¢/kWh

  Standard tiered plan (range 32.56¢/kWh to 40.7¢/kWh). Rates from PG&E's E-1 tiered tariff, effective June 1, 2026: Tier 1 for usage within your baseline allowance, Tier 2 above it. Your kit's output cuts your highest-priced usage first, so we use the Tier 2 rate. If your usage stays within your baseline allowance, your savings will be lower.

  Source: PG&E: Schedule E-1 residential tiered tariff (opens in a new tab) · checked Oct 22, 2026

• Discount program: None

  No CARE or FERA discount applied.

  You set this.

• Placement: Typical: well-placed: 1.10 kWh per watt per year

  How much power each watt of panel makes in a year in this spot. Basis: Model Base.

  Source: our financial model

  What research found: NREL PVWatts, roof panels tilted 20° facing south, six California cities: 1.59 to 1.79 kWh per watt a year (SunWatts: PV Watts output by city (20° tilt, 12% losses) (opens in a new tab)). · NREL PVWatts, San Diego, panels tilted 60° with no losses counted: 1.61 (Boston University (Powers and Sekera): Plug-in Solar Offsets and Savings, NREL PVWatts runs (Apr 2026) (opens in a new tab)). · EU PVGIS, vertical panel facing south in Los Angeles, San Francisco or Sacramento: 1.02 to 1.04 (EU Joint Research Centre: PVGIS solar calculator (opens in a new tab)). · A vertical balcony railing gets about 65% to 75% of an ideally tilted panel (Bright Saver: balcony solar savings calculator (railing output) (opens in a new tab)). · Bright Saver's Oakland pilot: an 800 W kit made about 2 kWh a day, about 0.91 kWh per watt a year (our arithmetic) (Bright Saver: Democratizing Solar, white paper (October 2025; free download after an email form) (opens in a new tab)).

• Power used at home: 90%

  Exports earn nothing, so size the kit to what you use during the day. Default 90% (our model's Base case).

  You set this.

  What research found: German environment agency (UBA): an average household uses about 45% of an 800 W kit's power as it is made, without a battery (Umweltbundesamt (German environment agency): plug-in solar devices (in German) (opens in a new tab)). · Fraunhofer ISE for E-Control (Austria): 49% to 95% for 250 W and 500 W kits, depending on kit size and household (Fraunhofer ISE for E-Control Austria: plug-in PV study (in German) (opens in a new tab)).

• Example kit (800 W, $1,000): 800 W AC, $1,000.00

  Our financial model's Base case: typical 800 W kit at the model's $1,000 average order value. Not a real product.

  Source: our financial model

• Power sent back to the grid: $0 per kWh

  Summaries of SB 868 say plug-in devices are kept off the net billing tariff, so exported power earns nothing. Not yet confirmed against the enacted text.

  Not yet confirmed against the enacted text of SB 868.

• Fixed monthly charge: Not reduced by solar

  Standard customers pay a fixed charge of about $24.15/month (CARE about $6, FERA about $12) that solar cannot remove.

  Source: NRG Clean Power: the new California fixed charge (opens in a new tab) · checked Oct 18, 2026