// Free Home Energy Tool
Find out whether a Powerwall actually pays off for your home — and by how much. This calculator goes beyond simple payback: it models TOU rate arbitrage savings, net metering value, the 30% federal tax credit, your backup hours by appliance, and how many units you actually need. No sign-up, no sales pitch — just the numbers.
| Year | Rate (¢/kWh) | Annual Saving | Cumulative | Net Position |
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Select which appliances to run during an outage and see how long your Powerwall(s) will last. Uses your unit count from Tab 1.
Answer a few questions about your home's energy needs and we'll recommend the right number of Powerwalls.
Common questions about Powerwall costs, savings, payback, and whether it makes sense for your home.
A single Powerwall 3 typically costs $12,000–$15,000 fully installed in the US, including the Powerwall unit, Gateway, installation labor, permits, and interconnection fees. Two units run about $17,000–$21,000. Prices vary significantly by installer, state, and whether you're adding it to an existing solar system vs. new installation. Before the 30% federal tax credit, a 2-unit system's net cost is roughly $11,900–$14,700 — one of the most important things most Powerwall calculators fail to show upfront.
Payback varies widely by location and rate structure. In California with TOU rates and NEM 3.0, a 2-unit Powerwall system can pay back in 6–9 years after the 30% ITC. In states with lower rates or full net metering, payback may be 12–18 years. Key variables: your utility's peak-to-off-peak rate spread (bigger spread = faster payback), whether you have solar, your utility's net metering policy, and whether you claim the 30% federal ITC. This calculator shows payback both with and without incentives in the 10-year table.
The Inflation Reduction Act (IRA) provides a 30% Investment Tax Credit (ITC) for residential battery storage systems through 2032. For a $17,000 2-unit installation, this credit is worth $5,100 off your federal taxes. Important: it's a tax credit (reduces taxes owed dollar-for-dollar), not a deduction. As of 2023, standalone battery storage (without solar) also qualifies for the 30% ITC — previously it required solar pairing. If you don't owe enough federal tax to use the full credit in year one, the excess rolls forward. Consult a tax professional for your specific situation.
Time-of-Use (TOU) electricity pricing charges different rates depending on the time of day — typically 3–5× higher during peak hours (usually 4–9 PM on weekdays) than off-peak hours (nights and weekends). A Powerwall on TOU mode charges during cheap off-peak hours and discharges during expensive peak hours, effectively letting you "buy low, sell high" with energy. In California, where PG&E and SCE peak rates can exceed 55¢/kWh vs. 14–16¢/kWh off-peak, this arbitrage alone can save $600–$1,200/year per Powerwall. This is often the largest single source of Powerwall savings — and most competing calculators ignore it entirely.
It depends on what you run. One Powerwall (13.5 kWh usable) will power: critical loads only (fridge, lights, WiFi, phone charging ~400W) for about 30–35 hours. Add a mini-split AC unit (+1,200W) and that drops to about 8–10 hours. Two Powerwalls (27 kWh) doubles those figures. Powerwall 3's maximum continuous output is 11.5 kW — enough to power a whole home including central AC. Use the Backup Duration tab above to model your specific appliance load.
Yes — Powerwall works as a standalone battery storage system without solar, charging from the grid during off-peak hours. Since the IRA's standalone battery storage provision (2023), you also qualify for the 30% federal tax credit without solar. However, without solar, the savings are limited to TOU rate arbitrage — you don't get the solar self-consumption or net metering benefits. In states with large TOU rate spreads (California, New York, Massachusetts), standalone Powerwall can still make financial sense. In flat-rate states, payback without solar is typically too long to justify without an outage resilience motivation.
California's Net Energy Metering 3.0 (NEM 3.0), which took effect April 2023, dramatically reduced the export credit for solar power sent back to the grid — from roughly 30¢/kWh to as low as 5–8¢/kWh depending on time of day. This means solar-only systems earn far less for excess production, but solar + Powerwall systems benefit because you can store excess solar and use it during peak hours at full retail value (25–55¢/kWh) rather than exporting it at 5¢. NEM 3.0 has made Powerwall essentially mandatory for new California solar installations to maintain good economics — a system that was marginal before NEM 3.0 is now clearly cost-effective with a Powerwall.
For most American homes, 2 Powerwalls (27 kWh) is the sweet spot for partial-to-full backup. For whole-home backup including central HVAC in a 2,000+ sq ft home: plan for 3–4 Powerwalls. If you also want to charge an EV during an outage, 4 units minimum. The "how many" tab above walks through a recommendation based on your home size, backup goal, and outage risk. Critical consideration: Powerwall 3 has an 11.5 kW continuous output limit — large HVAC systems or high-draw appliances may trip this limit even with multiple units. Check your peak load before sizing.
California is the #1 state due to NEM 3.0 + high TOU rate spreads + SGIP incentive (up to $200/kWh, worth ~$2,700 for 13.5 kWh). Hawaii has the highest electricity rates in the US (38¢/kWh avg) — fastest raw payback. New York offers the NY-Sun and Con Edison VDER programs. Massachusetts has SMART program benefits. Texas has growing demand charge programs. Worst states for Powerwall ROI: flat-rate states with no TOU options and low rates (Pacific Northwest, Louisiana) — payback can exceed the 10-year warranty period.
If you can afford cash, upfront purchase gives the best long-term ROI — you avoid interest costs and the 30% ITC credit is most valuable as a lump sum reduction. If you need financing, a HELOC or solar-specific loan at 5–7% APR is reasonable when annual savings exceed the interest cost. Be cautious of high-APR solar loans (12%+) marketed by some installers — these can significantly extend your effective payback period. The loan comparison in this calculator helps you model your specific numbers. Key rule: if annual savings > annual interest cost, the loan math can work.