Model your electric bill, solar system, battery and payback using current California utility data — with the assumptions, rates and official sources shown behind every result. No sign-up.
Solar payback calculator for California
Updated August 7, 2026 · reflecting 2026 LADWP net metering and SCE NEM 3.0 rules · by Cali Energy
How long until solar pays for itself in California? On LADWP, a $200/month bill with an $18,000 system pays back in about 8–9 years and nets roughly $35,000 over 25 years. On SCE’s NEM 3.0 the payback runs longer, because exported energy is worth less. Payback depends most on how much of your bill solar actually erases.
✓ Models LADWP net metering vs SCE NEM 3.0 — with the offset assumptions shown, not hidden. See every figure it uses ↓
Assumptions: monthly bill converted to usage at about 26¢/kWh (LADWP) or 34.5¢/kWh (SCE); system sized for a full offset at 1,600 kWh per kW–year and 400 W panels; solar–only, no battery. Bill–value offset assumed at about 88% on LADWP (near–retail credit) and 62% on SCE (low NEM 3.0 export credit — savings come mainly from self–consumption). Owner–bought, no federal tax credit. The 25–year net is nominal: it doesn’t model rate escalation, panel degradation, fixed charges or an inverter replacement — factors that can move the result either way. A ballpark, not a quote.
Get a real payback estimate for your roofThe rates and figures this calculator usestap to verify
Payback is system cost ÷ estimated annual savings. Here is every figure it uses. The utility rate and the “bill offset” share are Cali Energy planning assumptions — each is labeled and explained below, because they drive the result.
| LADWP — average rate | ~26¢ / kWh |
| LADWP — bill offset (net metering) | ~88% of bill value |
| SCE — average rate | ~34.5¢ / kWh |
| SCE — bill offset (NEM 3.0) | ~62% of bill value |
| California production per kW-year | ~1,600 kWh (NREL PVWatts) |
| Panel wattage | 400 W |
| Annual savings | annual bill × offset share |
| Simple payback | system cost ÷ annual savings |
| 25-year net | annual savings × 25 − system cost (nominal) |
The offset shares (88% LADWP, 62% SCE) are Cali Energy planning assumptions, not published rates: they approximate how much of a typical bill a solar-only system erases once you account for self-consumption and the value of exports. LADWP still offers near-full-retail net metering, so a well-sized system offsets most of the bill; SCE’s NEM 3.0 pays much less for exported energy, so the same system offsets a smaller share unless paired with a battery. The rates (~26¢ LADWP, ~34.5¢ SCE) are round planning figures — check your own bill. The 25-year net is a rough, nominal figure: it does not model future rate increases (which help solar) or panel degradation and an inverter replacement (which hurt), so treat it as a ballpark, not a forecast.
Example results you can reproduce
Each row enters a monthly bill, a system cost and a utility — enter the same values above to reproduce it.
| Bill · utility | System cost | Annual savings | Payback | 25-yr net |
|---|---|---|---|---|
| $200 · LADWP | $18,000 | $2,112 | 8.5 yr | $34,800 |
| $250 · SCE | $20,000 | $1,860 | 10.8 yr | $26,500 |
| $150 · LADWP | $14,000 | $1,584 | 8.8 yr | $25,600 |
How this calculator works
It multiplies your annual bill (monthly × 12) by a bill-offset share for your utility to estimate annual savings, then divides the system cost by that to get simple payback, and projects a nominal 25-year net. The offset share is the honest heart of the model: on LADWP’s near-full-retail net metering a solar-only system typically erases most of the bill (~88%), while on SCE’s NEM 3.0 exported energy earns far less, so the same system erases less (~62%) unless a battery lets you use more of your own power at night. These are Cali Energy planning figures, not a quote.
How to read your result
Simple payback is the break-even year — how long until savings equal the cash cost. The 25-year net is the rough lifetime gain in today’s dollars. The gap between a LADWP and an SCE result for the same bill is real and expected: it’s the net-metering rules, not the panels. If your payback looks long on SCE, that’s the NEM 3.0 export penalty — a battery is the usual fix.
What moves the result the most
The offset share dominates — it’s the difference between LADWP and SCE, and the single biggest lever. After that: your bill size, the system cost you enter, and (over the long run) future rate increases, which this tool deliberately leaves out to stay conservative. Financing raises the effective cost and lengthens payback versus a cash purchase.
Common questions
What do I need to use this calculator?
Your average monthly electric bill, an installed system cost (get one from a quote or our solar cost calculator), and your utility — LADWP or SCE.
Why do LADWP and SCE differ so much?
Net-metering rules. LADWP still credits exports at close to retail, so solar offsets most of the bill; SCE’s NEM 3.0 pays much less for exports, so a solar-only system offsets less of the bill and pays back more slowly.
Where do the 88% and 62% come from?
They are Cali Energy planning assumptions, not published tariffs — a reasonable estimate of the share of bill value a solar-only system erases under each utility’s rules. Your real share depends on your usage timing, system size and whether you add a battery.
Does this include the federal tax credit?
No. The 30% Residential Clean Energy Credit ended after December 31, 2025, so enter a gross 2026 cost. If a figure you saw elsewhere assumed the credit, it’s no longer applicable to owner-bought systems.
Should I add a battery on SCE?
Often yes — on NEM 3.0 a battery lets you use more of your own solar at night instead of exporting it cheaply, which raises the effective offset. It also adds cost, so model both.
Is the 25-year net a prediction?
No — it’s a nominal ballpark. It leaves out future rate increases (which would raise it) and degradation plus a likely inverter replacement (which would lower it). It shows scale, not a guaranteed number.
Is solar still worth it for me?
Payback is only part of the answer. Our is-solar-worth-it tool weighs payback against your situation, and our ownership tool compares cash, loan and lease.
Sources
- DSIRE — LADWP Net Metering program detail
- EnergySage — LADWP net metering (2026)
- EnergySage — SCE net metering / NEM 3.0 (2026)
- IRS — Residential Clean Energy Credit
- NREL PVWatts (production estimate used in calculator)
Estimates only, not a quote. Assumptions, rates, incentives and program rules can change — confirm current details with your utility, the program administrator or a licensed professional.
Read the full guide →