Honest economics, no sales scripts
Run the numbers yourself.
Two free tools, real per-utility rates, zero sales pressure. Where do you want to start?
Tell us about your home
Rough numbers are fine. We'll refine in a discovery call.
Using Ontario data: 5.9 peak sun hrs/day, SCE rates.
SCE is under NEM 3.0 — exports earn little, so battery storage is strongly recommended.
Estimates use 5.9 peak sun hours (Ontario), 4.5% annual rate inflation, and conservative production assumptions. Real designs use 12 months of utility data.
Investment breakdown
- Gross system cost
- $33,375
- − ~30% prepaid-lease savings*
- −$10,013
- Net cost
- $23,363
*Pass-through of the federal commercial clean-energy credit captured by our prepaid-lease financing — not a tax credit you file for. The 30% residential federal credit expired Dec 31, 2025; cash and loan purchases don't receive it.
25-year financial position
Cumulative cost or savings vs. staying on the grid (4.5% annual rate growth)
Monthly bill, before and after
Fire-season reality check
How long would a battery run your house?
PSPS shutoffs can last days. Toggle what you'd keep running and see what a Powerwall-class battery actually carries — no fear-selling, just watts and hours.
What would you keep running?
Toggle the loads that matter to your household during a shutoff — watch the house respond.
Runtime on battery alone
2.4days
With solar recharging the battery each day, essential loads (fridge, internet, lights) can ride out a multi-day PSPS shutoff — the battery refills faster than those loads drain it.
Now see it on your actual roof.
The numbers above assume a typical roof — yours isn't typical. Enter your address and we'll pull your real roof geometry, sun exposure, and usable panel area from satellite solar data.
Methodology: what's in the model
- Production: your city's peak sun hours (5.3–6.3 across our service area; 5.8 SoCal average if no city is selected), with an 80% derating factor from rated DC to AC production.
- Pricing: $3.25/W installed — the top of the $2.40–$3.25/W range we publish, priced conservatively for premium-tier equipment; ~$15,500 for a Powerwall-class battery installed. Real quotes vary with roof complexity.
- Export rates: NEM 3.0 blended export averages for SCE (~6¢), SDG&E (~6¢), and PG&E (~7¢). Municipal utilities use their own programs: LADWP and GWP near-retail credit, PWP and APU close behind, RPU (~9¢) and IID (~7¢) net billing.
- Rate inflation: 4.5% per year — the historical SoCal average since 2010 has run higher; we round down to stay conservative.
- Prepaid-lease savings: ~30% of gross cost, passed through from the federal commercial clean-energy credit our financing captures. This is not a residential tax credit you file for — the 30% residential credit ended Dec 31, 2025.
- Backup runtime: average continuous wattages including duty cycling, against 13.5 kWh usable per Powerwall-class unit. Daytime solar recharge extends essential-load runtime substantially.
- EV mode: 0.30 kWh per mile wall-to-wheels (a fair fleet-wide number including charging losses). Home-charged miles are added to the load the system is sized to cover, and the no-solar baseline includes what grid-charging those miles costs at your utility's rate.
- What's missing: SGIP battery rebate (waitlisted for general market), utility-specific TOU optimization, shade modeling, roof-pitch derate. Your real design includes all of these.
Last verified: July 2026 by Helios Energy Global. Rate anchors match the figures published across our guides.
Typical results at a glance.
Example output from this calculator for a $300/month bill at 5.8 peak sun hours — the utility you're on changes the answer more than anything else. Estimates, not quotes.
| Utility | Config | System size | Net cost | Year-1 savings | Payback | 25-yr advantage |
|---|---|---|---|---|---|---|
| SCE | Solar + battery | 6 kW | $24,500 | $3,409 | 7.2 yrs | $134,269 |
| SDG&E | Solar + battery | 4.5 kW | $21,088 | $3,353 | 6.3 yrs | $135,079 |
| LADWP | Solar only | 9.5 kW | $21,613 | $3,532 | 6.1 yrs | $137,659 |
| GWP | Solar only | 12 kW | $27,300 | $3,658 | 7.5 yrs | $131,971 |
Computed by the same model as the interactive tool above (net cost reflects the ~30% prepaid-lease pass-through; the residential federal credit expired Dec 31, 2025). LADWP and GWP rows are solar-only because near-retail net metering makes storage optional there.
Calculator questions, answered.
- How accurate is this solar savings calculator?
- It's a planning tool built on the same per-utility logic we use in real designs: blended 2026 retail rates, actual export-credit regimes (NEM 3.0 for SCE/SDG&E/PG&E, retail or utility-specific net metering for LADWP, GWP, PWP, APU, RPU, and IID), city-level peak sun hours, and 4.5% annual rate inflation. A real quote uses 12 months of your utility data, hourly shade modeling, and your exact roof — so treat the calculator as a ballpark, not a contract.
- Is there still a federal solar tax credit in 2026?
- No. The 30% federal residential tax credit expired December 31, 2025, and this calculator does not assume one. The ~30% reduction shown is a pass-through of the federal commercial clean-energy credit captured by prepaid-lease financing — a financing structure, not a tax filing. Cash and loan purchases price without it.
- Why does the calculator recommend a battery for SCE and SDG&E but not LADWP?
- Because the export rules are different. Under NEM 3.0 (SCE, SDG&E, PG&E), exported solar earns roughly 5-8¢/kWh while evening power costs 35-46¢ — a battery stores midday production for the expensive 4-9 PM window. LADWP and Glendale still credit exports near retail, so solar-only economics remain strong there and a battery is primarily for outage backup.
- How long will a battery run my house during a power outage?
- It depends entirely on what you back up. One Powerwall-class battery (13.5 kWh usable) runs essentials — refrigerator, internet, lights — for roughly 2-3 days, and longer with solar recharging it daily. Add central AC or EV charging and runtime drops to hours, which is why larger homes back up with two units. Use the backup runtime tool on this page to model your own loads.
- What does solar cost in Southern California in 2026?
- Most residential systems land between $2.40 and $3.25 per watt before incentives, depending on equipment, roof complexity, and system size. This calculator prices at the top of that range ($3.25/W) with premium-tier equipment to stay conservative. Every Helios quote itemizes each line.
See what your real design looks like.
This calculator gets you in the ballpark. A real design uses 12 months of your utility data, hourly shade modeling, and your specific roof — and it's free.