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), and city-level peak sun hours. Your grid bill is projected two ways — rising 6% a year (the U.S. average pace) and 10% a year (California's recent pace) — against a solar payment that is fixed (loan), escalates by a set percentage (PPA/lease), or is paid once upfront (cash, or a prepaid lease at the pass-through price). 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.

Why does the calculator assume California electricity rates rise 10% a year?

Because that's roughly what has been happening. EIA data puts California's average residential price at 17.0¢/kWh in 2015 and 32.5¢ in 2025 — about 6.7% a year compounded, and closer to 9.2% a year since 2019. SCE's bundled residential average went from 16.6¢ in 2017 to 32.4¢ in 2024 (10.0% a year); SDG&E and PG&E ran 10.2% and 9.3%. The U.S. average rose only 3.2% a year over the same decade, which is why we show both lines. You can change either assumption in the calculator, and the rate-history panel shows the actual EIA series for your utility with sources.

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. Every lease-structured price in the calculator — loan, PPA/lease, or prepaid lease — includes a ~30% pass-through of the federal commercial clean-energy credit that our prepaid-lease financing structure captures. That is a financing structure, not a tax filing; a straight cash purchase prices the full system cost.

Loan, PPA, cash, or prepaid lease — which saves more?

They trade different things. A loan has a fixed payment that ends, and you own the system — after payoff your only electricity cost is the small remaining grid bill. A PPA or lease starts lower and needs $0 down, but the payment escalates every year for the full term and you never build equity. Paying cash means no payment at all and full ownership from day one, at the full system price. A prepaid lease pays once, upfront, at the ~30% pass-through price — the lowest total cost of the four — with the lessor holding title for five years before ownership transfers to you at the start of year six. With California rates rising faster than any escalator, all four usually come out well ahead of staying on the grid; the calculator shows each so you can pick based on cash on hand, monthly cash flow, and how long you plan to stay in the home.

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 is transparent, owner-reviewed pricing with no hidden financing markups.

Honest economics, no sales scripts

Run the numbers yourself.

Two questions, one page — what solar saves you, and how long a battery keeps the lights on.

Estimates, not quotes.

Start with your bill

Rough numbers are fine. We'll refine in a discovery call.

Current monthly bill

$75$800+

Your city (optional)

Utility

SCE is under NEM 3.0 — exports earn little, so battery storage is strongly recommended.

System type

How you'd pay

Loan term

Interest rate (APR)

Est. monthly payment$181/mo

5.5 kW + 13.5 kWh battery · $33,375 installed

Already have a quote? Enter its monthly payment

Rate-increase assumptionsUS 6% · CA 10%

U.S. average pace

California pace

Sized to cover your usage at 5.8 peak sun hours (SoCal average). Grid bills grow at 6%/yr (U.S. average) and 10%/yr (California). Estimates, not a quote — real designs use 12 months of utility data.

Your bill in year 25 if you do nothing

$2,709/mo

At California's pace · $1,113/mo at the U.S. pace

Your solar payment

$181/mo

Fixed for 20 years, then $0

25-year savings

$127,740

At the U.S. pace · $263,405 at California's pace

Your grid bill vs. a solar payment

Monthly cost, year by year. The shaded gap is your savings.

Grid bill, CA pace
Grid bill, U.S. pace
With Helios
Savings
Extra savings at CA pace

“With Helios” is your loan payment plus the small grid bill that remains (~$15/mo today — the system offsets about 95% of your usage). After year 20 the payment stops and the panels keep producing.

Why we assume 10%/yr

What SCE rates actually did

Average residential price, ¢/kWh (EIA)

Year	U.S.	SCE
2015	12.7¢	—
2016	12.6¢-1%	—
2017	12.9¢+3%	16.6¢
2018	12.9¢0%	—
2019	13.0¢+1%	16.2¢
2020	13.2¢+1%	18.2¢+12%
2021	13.7¢+4%	21.3¢+17%
2022	15.0¢+10%	24.6¢+15%
2023	16.0¢+6%	32.3¢+31%
2024	16.5¢+3%	32.4¢0%
2025	17.3¢+5%	—
Now^*	18.1¢	34.5¢
Avg / yr	+3.2%	+10.0%
Since 2019	+4.9%	+14.9%

*Now: SCE Mar 2026 — Posted bundled residential tariff (CPUC Public Advocates Office Q1 2026 report), not an annual revenue average. U.S. 2026 YTD — EIA Electric Power Monthly, January–May 2026 average (preliminary). Not included in the averages above.

EIA-861 bundled residential average (CPUC SB 695 reports; EIA Table 6 for 2024). 2018 not published in citable form.

Sources

Equity

Every loan payment buys a bigger share of a system that keeps producing after it’s paid off.

Year 5: $3,214; 14% of a $23,363 system is yours
Year 10: $7,768; 33% of a $23,363 system is yours
Year 20 — paid off: $23,363; 100% of a $23,363 system is yours

Total paid over the loan: $43,437 on $23,363 financed — a $33,375 system after the ~30% prepaid-lease pass-through of the federal commercial clean-energy credit. From year 21 on, your only electricity cost is the small remaining grid bill.

25-year totals

Everything you'd pay for electricity over 25 years, each way.

Scenario	Stay on the grid	With Helios	You keep
Rates rise at the U.S. pace 6%/yr	$181,053	$53,313	$127,740
Rates rise at California's pace 10%/yr	$324,546	$61,140	$263,405

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.

Powerwall-class batteries (13.5 kWh usable each)

Runtime on battery alone

2.4days

230W avg load1 × 13.5 kWh = 13.5 kWh usable Tesla Certified Installer

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.

Whole-home vs. essentials backup Get a Powerwall quote

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. These set how much of your bill the system removes — ~95% with a battery or near-retail exports, ~60% for solar-only under NEM 3.0.
Grid-bill growth: two lines. 6% per year is the U.S.-average planning pace (EIA data: 4.9%/yr since 2019). 10% per year is California's pace (EIA statewide residential: 9.2%/yr since 2019; SCE 10.0%/yr, SDG&E 10.2%/yr, PG&E 9.3%/yr, 2017–2024). Both are editable, and the rate-history panel shows the underlying series with sources.
Solar payment: both structures start from the system cost net of the ~30% federal commercial clean-energy credit our prepaid-lease financing captures. A loan is amortized on that amount at the term and APR you set (default 20 years at 6.99%). A PPA/lease is priced on the same net amount, with the year-1 payment set so the escalating stream (2.9%/yr default) is worth the same as financing at 9%. Cash pays the full price upfront with no pass-through; a prepaid lease pays the pass-through price upfront. For both, the savings totals are net of that upfront cost and the chart shows only the remaining grid bill. If you have a real quote, type its payment (or price) in and the chart uses that instead.
What remains with solar: the un-offset share of today's bill, never less than a $15/month connection charge, growing at the same rate as the scenario's grid bill. After a loan is paid off, or a PPA term ends, we model $0 solar payments.
Equity: for a loan, the principal repaid to date — your ownership stake in the system. PPA and lease customers build none; the third party owns and maintains the equipment.
Federal credit: the 30% residential credit ended Dec 31, 2025 and is not assumed anywhere. The ~30% inside loan and PPA/lease pricing is the commercial credit our prepaid-lease financing passes through — not something you file for.
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: August 2026 by Helios Energy Global. Rate anchors match the figures published across our guides; historical rates are EIA Form 861 bundled residential averages as reprinted in CPUC SB 695 reports.

Typical results at a glance.

A $300/month bill today becomes $1,215/month in year 25 at the U.S. pace and $2,955/month at California's. Here's that bill against a 20-year loan payment 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	Solar payment	25-yr savings (U.S. pace)	25-yr savings (CA pace)
SCE	Solar + battery	6 kW	$190/mo	$141,493	$289,734
SDG&E	Solar + battery	4.5 kW	$163/mo	$144,771	$290,582
LADWP	Solar only	9.5 kW	$167/mo	$147,453	$296,163
GWP	Solar only	12 kW	$211/mo	$136,878	$285,589

Computed by the same model as the interactive tool above: 20-year loan at 6.99% APR on the system cost net of the ~30% prepaid-lease pass-through, grid bills growing 6%/yr (U.S.) and 10%/yr (California), savings net of the small grid bill that remains. 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), and city-level peak sun hours. Your grid bill is projected two ways — rising 6% a year (the U.S. average pace) and 10% a year (California's recent pace) — against a solar payment that is fixed (loan), escalates by a set percentage (PPA/lease), or is paid once upfront (cash, or a prepaid lease at the pass-through price). 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.
Why does the calculator assume California electricity rates rise 10% a year?: Because that's roughly what has been happening. EIA data puts California's average residential price at 17.0¢/kWh in 2015 and 32.5¢ in 2025 — about 6.7% a year compounded, and closer to 9.2% a year since 2019. SCE's bundled residential average went from 16.6¢ in 2017 to 32.4¢ in 2024 (10.0% a year); SDG&E and PG&E ran 10.2% and 9.3%. The U.S. average rose only 3.2% a year over the same decade, which is why we show both lines. You can change either assumption in the calculator, and the rate-history panel shows the actual EIA series for your utility with sources.
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. Every lease-structured price in the calculator — loan, PPA/lease, or prepaid lease — includes a ~30% pass-through of the federal commercial clean-energy credit that our prepaid-lease financing structure captures. That is a financing structure, not a tax filing; a straight cash purchase prices the full system cost.
Loan, PPA, cash, or prepaid lease — which saves more?: They trade different things. A loan has a fixed payment that ends, and you own the system — after payoff your only electricity cost is the small remaining grid bill. A PPA or lease starts lower and needs $0 down, but the payment escalates every year for the full term and you never build equity. Paying cash means no payment at all and full ownership from day one, at the full system price. A prepaid lease pays once, upfront, at the ~30% pass-through price — the lowest total cost of the four — with the lessor holding title for five years before ownership transfers to you at the start of year six. With California rates rising faster than any escalator, all four usually come out well ahead of staying on the grid; the calculator shows each so you can pick based on cash on hand, monthly cash flow, and how long you plan to stay in the home.
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 is transparent, owner-reviewed pricing with no hidden financing markups.

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.

Get a free quote (310) 564-8817