A 13.5-kilowatt-hour Tesla Powerwall 3 costs between $12,000 and $16,000 installed, which shrinks to $8,400 to $11,200 after the 30 percent federal Investment Tax Credit. Most homeowners who buy one are purchasing insurance: the lights stay on when PG&E fails, and nothing else happens. Ever. Your battery sits in the garage like an overqualified security guard working a building with no crime, waiting for an emergency that arrives twice a year if you are unlucky and never if you are not.
California state senator Josh Becker thinks that battery should have a second job.
Senate Bill 913, introduced in March 2026, would classify customer-owned batteries, electric vehicles, and smart thermostats as Resource Adequacy capacity. That is not a marketing label. Resource Adequacy is the regulatory mechanism through which the California grid operator compels utilities to purchase enough generation to meet peak demand, with penalties from the CPUC for those who fall short. Gas peaker plants sell this capacity today and have sold it for decades. Your Powerwall cannot. SB 913 would let energy aggregators bundle thousands of home batteries into virtual power plants and bid that combined capacity into the same market where a 50-megawatt gas turbine currently competes unchallenged, transforming a $14,000 appliance that earns nothing into an asset that generates revenue every month it stays connected to the grid.
Three Scenarios, Same Battery, Different Paychecks
I ran the numbers on a single Powerwall 3 in a typical California home. Installed cost $14,000, dropping to $9,800 after the ITC.
| Strategy | Annual Revenue | Payback (after ITC) |
|---|---|---|
| Backup only | $0 | Never |
| TOU arbitrage | $240–$400 | 24–41 years |
| RA + VPP (post-SB 913) | $686–$786 | 12–14 years |
Backup-only is self-explanatory: you spent ten grand on peace of mind, and the ROI is emotional.
TOU arbitrage, which is what most battery owners do, means charging overnight at $0.25 to $0.30 per kilowatt-hour and discharging during peak hours at $0.45 to $0.55. You capture a $0.20 spread across roughly 10 kWh of usable capacity per cycle, and at 300 effective cycles per year, adjusting for backup-priority days, weekends with lower rate differentials, and seasonal variation, you land at $240 to $400 annually. The battery outlasts your patience at that rate, with payback stretching to 24 to 41 years.
Scenario C stacks three revenue streams that current regulation blocks. First, participation payments: Ava Community Energy's SmartHome Battery program, launched April 2026 with $11 million in funding, pays $3 per kilowatt-hour per month in ongoing participation for shared capacity, which on a 13.5 kWh system totals $40.50 monthly, $486 per year. Second, emergency dispatch at $2 per kilowatt-hour: Tesla VPP participants report payouts of $400 to $750 per grid emergency event, and conservatively assuming 10 to 15 events annually at 10 kWh dispatched yields $200 to $300 in additional revenue. Third, residual TOU arbitrage on non-dispatched days.
Combined payback after the tax credit: 12 to 14 years, inside most manufacturers' 15-year warranty windows. Not spectacular as an investment. But it moves the battery from pure cost center to an asset that partially services its own debt while still protecting you in a blackout.
Who Controls the Switch
This is the catch, and it is a real one.
When your battery carries RA obligations, the aggregator controls dispatch. Not you. Ava requires Powerwall owners to share 80 percent of stored energy with the virtual power plant. NEM 2 customers enrolling less than 4 kWh get a fixed daily discharge schedule dictated by the aggregator: two hours per weekday, every week, the full year, with the specific windows emailed to you each October like a class syllabus you did not sign up for.
You paid $14,000 for backup power, and now someone else decides what four-fifths of that capacity does for $40 a month.
Picture the scenario every battery owner dreads: a local blackout strikes your street while CAISO simultaneously declares a grid emergency. Your battery has RA commitments. Does it keep your refrigerator running, or does it discharge to the grid because the aggregator's software determined that the statewide need outweighs your spoiled groceries? Ava's program documentation does not explicitly resolve this conflict, and the answer depends on contract terms, software priority logic, and whether the system even distinguishes between a local outage and a grid-wide event at the moment of dispatch.
130,000 Batteries Need an Operating System
Lunar Energy, founded by former Tesla Energy head Kunal Girotra, raised $232 million in February 2026 to build exactly this layer, bringing total funding past $530 million. What makes Lunar interesting is not the hardware, which sits at a 10 percent price premium over Tesla's Powerwall, but the Gridshare software platform that already manages all of Sunrun's virtual power plant operations, coordinating nearly 130,000 home batteries made by various manufacturers across the country.
Girotra calls this an "Android-like software strategy," contrasting it with the walled-garden approaches that Tesla and Enphase pursue, where only their own batteries work with their own software. If SB 913 passes, the aggregation layer becomes the chokepoint: utilities need to replace a 50-megawatt gas plant with distributed capacity, no single manufacturer has enough units in one utility territory to do it alone, and whoever runs the orchestration software across multiple brands captures the toll road. Lunar is building that road. Whether they end up owning it is a different question that depends on how many competitors Gridshare's interoperability advantage attracts versus how many it deters.
If You Are Installing a Battery This Year
Size the battery for your backup needs first. A 13.5 kWh Powerwall covers critical loads for 12 to 24 hours in most homes, and that core function has not changed. But before signing with an installer, ask whether the system supports third-party VPP enrollment and whether the inverter allows aggregation software beyond the manufacturer's own app. Proprietary lockout limits your options if RA markets open.
If you are in Ava Community Energy's Northern California service territory, the SmartHome Battery program is live now. Income-qualified customers receive $500 per kilowatt-hour in installation rebates, offsetting $6,750 on a 13.5 kWh system on top of the federal ITC, while market-rate customers receive $90 per kilowatt-hour. Both tiers get the $3 per kilowatt-hour monthly participation payment for the duration of enrollment.
For everyone else: SB 913 remains in committee. Senator Becker introduced it with backing from Advanced Energy United and Deploy Action, but no floor vote is scheduled. If the bill dies, your Powerwall goes back to waiting for blackouts. Watch also for the companion measure, AB 1975, which tackles load flexibility from the demand side. Together they represent California's first serious legislative push to treat home batteries as grid infrastructure rather than consumer electronics.
Limitations of This Analysis
Several caveats constrain the numbers above. Ava's $3-per-kilowatt-hour monthly rate is a single program in a single service territory, not a market-wide RA price, and actual Resource Adequacy capacity payments fluctuate with CPUC procurement cycles. Tesla VPP payout figures are self-reported by homeowners on Reddit and Tesla forums without independent audit.
Battery degradation from accelerated VPP cycling reduces usable capacity over time, and the payback math above does not model degradation curves or potential warranty implications of commercial dispatch schedules. All calculations assume NEM 2.0 time-of-use rates. Homeowners on NEM 3.0 face materially lower export compensation, which shrinks the TOU arbitrage component.
SB 913 has not passed. Even if it does, the regulatory pathway from bill to operational RA market participation involves CPUC rulemaking, utility compliance filings, and aggregator certification that could take 18 to 24 months after the governor's signature.