Solar payback period in California: how to work out yours in 2026

The formula, and one worked example

Simple payback (years) = net cash price ÷ first-year reduction in your utility bill.

The net cash price is the price after any incentive you have in writing. The first-year bill reduction is today’s annual bill minus the annual bill the quote says you will still pay. Both numbers are in the state disclosure documents, which include the total cost and “a one-year bill savings estimate.”

Simple payback leaves out financing, maintenance, equipment replacement, panel degradation and future rate changes. It is a screen, not a forecast. The California solar cost calculator runs this arithmetic on your bill and quote.

What moves payback in California

1. The price you pay

Berkeley Lab’s 2026 data update found median prices among the 100 largest residential installers ranging from $2.4 to $6.3 per watt for systems installed in 2025, with roughly 60% below $4 per watt (Berkeley Lab). The same system at a lower price per watt pays back sooner in direct proportion. Get at least two quotes and compare price per watt.

2. How much solar you use at home

On PG&E, SCE and SDG&E, systems that applied for interconnection since April 15, 2023 take service on the Net Billing Tariff. Exports are credited at Avoided Cost Calculator values the CPUC says are “usually lower than the retail rate” (CPUC). A kWh you use at home saves what you would have paid for it; a kWh you export earns less. Ask the proposal for the share of production it assumes you use yourself. City-owned utilities set their own credit: SMUD pays 9.6 cents per kWh for exports from June 1, 2026 (SMUD), and Roseville Electric $0.0691 per kWh for systems interconnected since October 1, 2018 (Roseville).

3. Your utility’s rates

The higher your rate, the more each self-used kWh saves. The CPUC Public Advocates Office reported residential average rates of $0.337 per kWh for PG&E, $0.344 for SCE and $0.455 for SDG&E in June 2026 (Q2 2026 report). Your own time-of-use plan matters more than the average; see PG&E, SCE and SDG&E rates compared.

4. Charges solar cannot remove

PG&E’s monthly Base Services Charge, about $24 for most customers from March 2026, “is not eligible to be offset by monthly generation credits” (PG&E). A savings estimate that zeroes your bill has left something out.

5. Incentives that are gone or closed

Older payback figures often subtracted a 30% federal credit. The IRS says the credit “is not available for any property placed in service after December 31, 2025” (IRS). For a system installed now, rerun any estimate on the full cash price. What still exists is in California solar incentives in 2026.

6. The rate-increase assumption

Many estimates assume utility rates will rise, which makes savings grow each year. The CPUC says “solar providers are allowed to use a maximum electricity rate escalation of 10% in any calculation, as of 2025,” and that “electricity bill savings estimates do not guarantee savings” (CPUC). Ask which rate is used, and for the payback at a lower one.

Payback with a battery

A battery adds cost and changes what your solar is worth. Among cash-purchase systems installed in 2025, Berkeley Lab found median prices $2.1 per watt higher for solar paired with storage than for solar alone (Berkeley Lab). Under net billing, the battery’s job is to hold daytime solar for evening use instead of exporting it for a lower credit. Whether that repays the extra cost depends on your evening use and your rate plan.

Incentives can shorten it. On September 23, 2026 the SGIP tracker showed most residential categories closed. SMUD’s battery incentive was $300 per kWh, up to $6,000 per household, for projects submitted from that date (SMUD). The detailed math is in battery payback under NEM 3.0.

Payback when you do not pay cash

With a loan, add the interest and fees to the price before you divide. With a lease or PPA there is no upfront price to pay back; the question becomes whether the solar payment plus the remaining utility bill is lower than the bill you have now, every year of the contract, after the escalator. The CPUC says escalators are “typically in the range of a 1 percent to 3 percent increase above the rate you paid in the previous year.” See lease, PPA, loan and cash compared and what no-upfront-cost solar costs over the contract.

Stress-test a quote’s payback before you sign

The CPUC’s own words on payback under net billing, from Resolution E-5301: “D.22-12-056 did not guarantee customers an exact simple payback period given the natural variation in customer usage and system generation” (CPUC, November 30, 2023). Ask the provider to rerun the proposal with:

• production 10% lower than the model;
• a lower rate-increase assumption than the one it used;
• the full cash price, with no incentive you do not have in writing;
• the remaining bill including fixed charges;
• the cost of any expected equipment replacement within the payback period, such as a replacement inverter.

If payback still works, the decision is sturdier. If it only works on the best case, treat that as a warning. Whether solar is worth it for you overall, beyond payback, is in is solar worth it in California, which also covers how net billing changed the answer.

A referral request is optional and separate

California Rate Relief is a referral service. We are not a licensed contractor. A referral request does not produce a payback figure or promise savings; any estimate comes from the provider, in writing.