Time-of-use arbitrage
Charge when your all-in electricity rate is lower, then discharge during expensive evening hours. A larger battery gives you more energy to shift and more room to capture the rate spread.
Power banking for SDGE customers
Bigger batteries make energy arbitrage useful for more of the home.
Tesla Powerwall can turn lower-cost electricity and midday solar into evening savings. Size the system around your rates, charging habits, solar production, and the amount of energy your home actually uses.
Backup power
Keep selected circuits or more of the home running during outages. The right number of batteries depends on your critical loads, solar production, and outage expectations.
Solar self-consumption
Store midday solar instead of exporting it, then use that energy after sunset. This is especially relevant when export credits are lower than the value of avoiding an evening import.
Where the savings come from
Powerwall can charge from the grid during lower-cost hours or from solar during the day, then cover evening usage when electricity costs more. The potential bill savings come from the usable energy shifted, the rate difference, and how often the cycle happens.
- Charge from lower-cost electricity
- Store midday solar for use after sunset
- Shift more evening usage with additional capacity
- Use the same stored energy for home and EV charging
How much battery do you need?
Use Tesla’s address-based design process as the starting point, then compare it against your actual Green Button usage and the circuits you want protected.
- Powerwall 3 has 13.5 kWh of nominal battery energy; actual usable energy depends on operating limits, reserve settings, and system losses.
- One battery can be a meaningful starting point. Larger homes, electric heat, pool equipment, EV charging, or longer backup goals may justify multiple units.
- Do not size from annual kWh alone. Look at your evening peak, critical circuits, solar production, and how long you want backup to last.
Power banking is not automatically a money-maker
Savings depend on the difference between the charging and discharging rates, round-trip losses, battery degradation, financing or installation cost, and how consistently you can shift load. Model your own usage before treating arbitrage as a payback promise. The backup and solar-self-consumption value may matter just as much as the bill savings.
Run the arbitrage math for your battery
Charge a battery when electricity is cheap, then use it during the brutal 4–9 PM peak. The default EV-TOU-5 summer rates are nearly 80¢ peak versus about 13¢ overnight.
Current SDGE EV-TOU-5 total-rate presets
Effective June 1, 2026. Choose a season, then adjust the rates to match your own plan and bill.
Your modeled result
Delivered per cycle
12.2 kWh
Grid energy to recharge
13.5 kWh
Headline rate spread
$0.665/kWh
Gross annual savings
$2,884
Simple payback
5.2 years
Other bill charges, annualized
$708
Shown as bill context, not claimed as battery savings.
PCIA and similar line items are not automatically erased by battery shifting. Their actual effect depends on whether they are fixed or tied to your imported kWh. Savings include charging losses, but exclude financing, degradation, taxes, export credits, maintenance, and backup-power value.
Start with your latest SDGE bill
A quick screening estimate: enter your most recent monthly bill, then estimate how much of it lands in expensive hours and how much of that usage a battery could shift.
Quick estimate
Annual electricity bill
$3,000
Estimated monthly savings
$44
Estimated annual savings
$525
This is a rough bill-based estimate, not a quote. Actual savings depend on your SDGE plan, solar exports, battery size, losses, and how consistently you shift usage.
Referral disclosure: this page links to Tesla’s energy design flow using referral code david943402. The referrer may receive benefits, and Tesla offers, pricing, installation availability, and incentives can change. Review the current design and terms directly with Tesla.