Plug-In Solar Savings in California
- Mar 17
- 4 min read
Updated: Jul 3
How Much Can You Save with Plug-In Solar in California?
In short: California NEM homeowners can save $360-$792/year by adding a plug-in solar expansion kit, depending on their utility. PG&E customers save ~$360/year (2-panel) to ~$660/year (4-panel). SDG&E customers save the most at $432-$792/year due to higher rates. All kits pay for themselves in under 5 years.
The math on plug-in solar in California is straightforward: take some of the highest electricity rates in the country, add 260+ days of sunshine per year, and the savings add up fast.
This page shows realistic, conservative savings estimates for NEM 1.0 and NEM 2.0 customers based on actual California NEM credit rates.
How NEM Expansion Kits Save You Money
Unlike standalone plug-in solar, Bright Saver's NEM Expansion Kits work with your existing rooftop solar and net metering agreement. Every kilowatt-hour your backyard panels generate either:
Powers your home directly — saving you the full retail rate (up to $0.45+/kWh)
Flows back to the grid — earning you NEM credits at your existing NEM rate
Either way, you save. The conservative estimates below use NEM credit rates only, since that's the baseline value of every kWh produced.
Savings by Utility
PG&E Customers
At NEM rates of ~$0.30/kWh:
System | Price + Tax* | Annual NEM Credits | Payback | 10-Year Net Savings |
NEM 2-Panel | $1,649 | $360/year | 4.6 years | $1,951 |
NEM 4-Panel | $2,583 | $660/year | 3.9 years | $4,017 |
SCE Customers
At NEM rates of ~$0.32/kWh:
System | Price + Tax* | Annual NEM Credits | Payback | 10-Year Net Savings |
NEM 2-Panel | $1,649 | $384/year | 4.3 years | $2,191 |
NEM 4-Panel | $2,583 | $704/year | 3.7 years | $4,457 |
SDG&E Customers
At NEM rates of ~$0.36/kWh — the highest of any major California utility:
System | Price + Tax* | Annual NEM Credits | Payback | 10-Year Net Savings |
NEM 2-Panel | $1,649 | $432/year | 3.8 years | $2,671 |
NEM 4-Panel | $2,583 | $792/year | 3.3 years | $5,337 |
Includes 10% estimated sales tax.
Why the Math Gets Better Every Year
California electricity rates have been rising 5 to 8% per year consistently. Your NEM credits grow as rates increase, but your kit cost is locked in at day one.
Year | PG&E NEM Rate | 2-Panel Credits | 4-Panel Credits |
Year 1 | $0.30/kWh | $360 | $660 |
Year 5 | $0.37/kWh | $444 | $814 |
Year 10 | $0.47/kWh | $564 | $1,034 |
Year 20 | $0.76/kWh | $912 | $1,672 |
Over 20 years, a 2-panel kit generates over $11,000 in cumulative NEM credits on a $1,649 investment. A 4-panel kit generates over $21,000 on a $2,583 investment.
How Plug-In Solar Compares to Other Investments
Investment | Cost | Annual Return | Payback |
Plug-in solar (PG&E) | $1,649 | $360/yr (22%) | 4.6 yrs |
Plug-in solar (SDG&E) | $1,649 | $432/yr (26%) | 3.8 yrs |
High-yield savings | $1,649 | ~$74/yr (4.5%) | N/A |
S&P 500 (hist. avg) | $1,649 | ~$165/yr (10%) | N/A |
Plug-in solar returns 22-26% annually in avoided electricity costs — and the return grows as rates increase. Unlike financial investments, this return is tax-free (you're avoiding a cost, not earning income).
Real Scenarios
Bay Area homeowner, PG&E, NEM 2.0:
Got an EV last year, true-up bill went from $200 to $800. Added a 2-panel NEM Expansion Kit in the backyard. $360/year in additional NEM credits, offsetting about half the EV charging cost. Payback in 4.6 years, then free credits for 15+ more years.
San Diego homeowner, SDG&E, NEM 1.0:
4-panel kit in the backyard. At SDG&E's higher rates, earning $792/year in NEM credits. System pays for itself in 3.3 years. Over 20 years, $15,000+ in cumulative savings.
LA homeowner, SCE, NEM 2.0:
Added a heat pump, electricity usage jumped. 2-panel kit on the patio. $384/year in NEM credits. The kit cost less than two months of the increased electricity bill.
Self-Consumption vs. NEM Credits
When your home is using more electricity than your panels produce (common during high-use periods), the solar energy gets consumed directly. In that case, you're saving at your full retail rate — which is even higher than the NEM credit rate.
The estimates above use only the NEM credit rate ($0.30-$0.36/kWh), so your actual savings may be higher if your home consumes a significant portion of the solar output directly.
How NEM Credits Appear on Your Bill
Understanding how NEM credits translate to actual bill savings is important. Here's how it works for most California utilities:
Monthly billing: Each month, your utility tracks the net energy flow — how much you consumed minus how much you exported. If you exported more than you consumed, those excess kWh become NEM credits that carry forward.
Annual true-up: Once a year (on your true-up date), your utility calculates the net balance. If you have excess credits, you receive a payment at the Net Surplus Compensation rate. If you owe, you pay the balance. Most NEM customers aim to zero out or have a small credit at true-up.
Where plug-in solar helps: If your true-up bill has been creeping up because your energy usage grew (EV, heat pump, family expansion), a plug-in expansion kit generates additional credits each month that offset the increase. You don't need to change your rate plan, your billing cycle, or your utility agreement.
FAQ
Are these savings guaranteed?
No. They depend on your NEM rate, sun exposure, panel placement, and energy usage patterns. We used conservative NEM credit rates — your actual savings may be higher.
What about the NEM 3.0 / Net Billing Tariff?
These kits are designed for existing NEM 1.0 and NEM 2.0 customers. The NEM expansion rule lets you add up to 1 kW or 10% of your original system size without losing your existing NEM rate.
Will savings increase over time?
Almost certainly. California rates have been rising 5 to 8% per year consistently. Your NEM credits grow proportionally.
What about the 4-panel system clipping?
The 4-panel system pairs 1,600W of panels with a 900W inverter. The inverter clips peak output on the sunniest midday hours, but annual energy lost to clipping is only about 10%. The extra panels capture significantly more energy in mornings, afternoons, and cloudy conditions.
Start saving today.
NEM 2-Panel Kit: $1,499 (+ tax)
NEM 4-Panel Kit: $2,348 (+ tax)
Free pickup from our Oakland or Los Angeles warehouses. Delivery + installation support available within 50 miles of Oakland for $349.
Bright Saver is a 501(c)(3) nonprofit. Our mission: Help Americans save on electricity bills by making plug-in solar affordable and accessible to all.