Time-of-Use Rates: Why Batteries Are a Financial No-Brainer in Some States

For most of the last century, residential electricity was priced one way: a flat rate for every kilowatt-hour, regardless of when you used it. That era is ending fast. In 2026, more than 40 million U.S. households are on some version of time-of-use (TOU) pricing — and that number is climbing every year [1]. In some states, TOU is now the default. And in those states, a home battery is no longer a luxury or a backup accessory. It is a genuine arbitrage tool that can turn your utility bill inside out.

If you live in California, Hawaii, Massachusetts, New York, or a growing list of other states, the math on batteries has fundamentally changed. Here is what you need to know.

What Time-of-Use Pricing Actually Does to Your Bill

TOU rates charge different prices for electricity depending on the time of day. Utilities use this to steer demand away from expensive peak hours — usually late afternoon and early evening, when air conditioners, cooking, EV charging, and returning workers all pile onto the grid at once.

A typical residential TOU rate has three tiers: off-peak (usually midnight to early morning), mid-peak (daytime), and on-peak (roughly 4 PM to 9 PM). The spread between off-peak and on-peak can be dramatic. Pacific Gas & Electric's EV2-A rate, for example, charges about $0.31/kWh off-peak and $0.62/kWh during peak hours — a 2x multiplier [2]. Southern California Edison's TOU-D-Prime hits $0.54/kWh during summer on-peak windows, compared to about $0.28/kWh off-peak.

On Oahu, Hawaiian Electric's TOU rate charges roughly $0.43/kWh during the 5–10 PM evening peak and $0.31/kWh overnight [3]. In New York, Con Edison's residential TOU plan shows a similar pattern: around $0.37/kWh on summer peak and $0.14/kWh off-peak.

Translation: the same kilowatt-hour of electricity can cost you twice as much depending on the clock.

Why This Changes the Battery Economics

In a flat-rate world, a home battery mostly served two purposes: backup during outages, and self-consumption of your own solar production. Both are valuable, but neither generates pure cash flow. The payback came slowly, mostly through avoided grid purchases at a single flat price.

TOU rates introduce a third role: arbitrage. You can charge the battery when electricity is cheap — either from your solar panels during the day or from the grid during off-peak hours — and discharge it during peak hours, when you would otherwise be paying peak prices. Every kilowatt-hour you shift from on-peak to off-peak pockets you the difference.

With a 13.5 kWh Tesla Powerwall 3, cycled roughly once per day, that comes to about 4,900 kWh shifted per year. At a $0.30/kWh spread (peak minus off-peak), that is $1,470 in annual arbitrage value — on top of any solar savings, backup protection, or incentive payments. Over the 10-year warranty period, that is close to $15,000 in avoided peak costs from a single battery cycling pattern [4].

California Under NEM 3.0: The Clearest Case

California is the most extreme example of why batteries and TOU are a match. Under the old NEM 2.0 rules, solar-only homes got credited for excess generation at roughly the retail rate — meaning a grid-tied solar system with no battery was economically fine. NEM 3.0 changed that. Excess solar exports now receive "Avoided Cost Calculator" rates that are typically $0.05–$0.12/kWh, a fraction of the $0.40–$0.60/kWh you pay on peak [5].

The implication is simple: under NEM 3.0, selling your solar back to the grid during the day is a losing trade. Storing it and using it yourself during peak hours is a winning one. That is why battery attachment rates on new California solar installations have jumped from around 10% in 2022 to over 80% in 2026 [6]. A battery is no longer optional equipment — it is the asset that makes the whole system pencil out.

Realistic numbers for a California home with an 8 kW solar system and a 13.5 kWh battery in 2026: the system produces around 12,000 kWh annually, offsets most daytime load directly, and shifts another 4,500+ kWh of evening usage from peak to stored solar. Total annual electricity savings frequently exceed $3,200 compared to a grid-only home [4][5].

Hawaii, Massachusetts, New York: Where TOU Already Pays

Hawaii has the highest residential electricity rates in the country, averaging over $0.42/kWh statewide [7]. The Battery Bonus program on Oahu paid incentives to homeowners who dispatched stored solar energy to the grid during evening peak hours. While the original program closed, its successor tariffs and TOU rate structures continue to reward batteries heavily. Payback periods under 5 years are common for solar-plus-battery systems in Hawaii.

Massachusetts pairs TOU rates with the ConnectedSolutions program, which pays homeowners roughly $225–$275 per kilowatt of battery capacity dispatched during grid peaks each summer. A 10 kW battery can earn $2,000+ per year from ConnectedSolutions alone, stacked on top of TOU arbitrage savings and SMART program credits [8].

New York has moved aggressively toward TOU defaults for residential customers, and utilities like Con Edison and National Grid have active battery incentive programs. The NY-Sun program and the new Clean Energy Standard storage adders increase the direct payment for each kWh of installed battery storage.

Where TOU + Battery Does Not Yet Pay

Let's be honest about where the math breaks down. States with low, flat residential rates and no battery incentives have longer payback periods for TOU-driven arbitrage. That includes much of the Southeast (North Carolina, Georgia, South Carolina), parts of the Mountain West, and rural areas where electricity still costs under $0.12/kWh on a flat schedule.

In those markets, a battery still makes sense for backup power and for grid resiliency, but pure arbitrage economics are thin. If your on-peak to off-peak spread is only $0.03–$0.05/kWh, a $12,000–$15,000 battery install won't pay itself off purely on time-shifting.

The trend line, however, is clear. Utilities across the country are moving toward TOU rate structures, and peak-to-off-peak spreads are widening as utilities try to manage grid stress without building expensive new peaker plants. What looks marginal today will likely pencil out within a few years.

How to Check If TOU Makes a Battery Worth It for You

There are three questions that determine whether a battery is a financial no-brainer in your market:

First, what is your peak-to-off-peak spread? Look at your utility's rate schedule and calculate the gap. Anything above $0.20/kWh is a strong arbitrage environment. Between $0.10 and $0.20 is moderate. Below $0.10 is thin.

Second, are you on NEM 3.0 or a similar net-billing tariff? If your utility has shifted from full retail net metering to avoided-cost export rates, a battery is essentially required to capture the full value of your solar investment.

Third, do you have a state or utility battery program? California's SGIP, Massachusetts ConnectedSolutions, Rhode Island and Connecticut's battery programs, New York's storage incentives, and Colorado's Xcel battery connect program all add thousands of dollars of direct incentive value [9].

The Bottom Line

Batteries used to be pitched primarily as insurance against blackouts. In the TOU era, they have become a straightforward financial asset in the right markets — generating returns by shifting cheap off-peak and solar-generated electricity into expensive peak hours. For homeowners in California, Hawaii, Massachusetts, New York, and a handful of other states, the math is no longer marginal. It is compelling.

Want to see how time-of-use rates affect your specific situation? Enter your zip code into the EnergyScout solar + battery calculator to get personalized savings estimates based on your local TOU structure, utility rates, and available incentives. You can also browse battery rebate programs by state or compare solar-only vs solar-plus-battery economics side by side.

The grid is being priced differently than it used to be. The good news is that batteries finally give you a way to price it back.

Sources

1. U.S. Energy Information Administration. "Residential Time-of-Use Electric Rates." https://www.eia.gov/todayinenergy/
2. Pacific Gas & Electric. "Time-of-Use Rate Plans." https://www.pge.com/en/account/rate-plans/find-your-best-rate-plan/time-of-use-rates.html
3. Hawaiian Electric. "Residential Time-of-Use Rates." https://www.hawaiianelectric.com/billing-and-payment/rates-and-regulations
4. National Renewable Energy Laboratory. "Residential Battery Economics Under Time-of-Use Rates." https://www.nrel.gov/docs/fy23osti/
5. California Public Utilities Commission. "Net Billing Tariff (NEM 3.0) Overview." https://www.cpuc.ca.gov/industries-and-topics/electrical-energy/demand-side-management/net-energy-metering
6. Solar Energy Industries Association (SEIA). "California Solar + Storage Attachment Rates." https://www.seia.org/research-resources
7. EIA. "Electric Power Monthly — Average Retail Price of Electricity by State." https://www.eia.gov/electricity/monthly/
8. Mass Save. "ConnectedSolutions Battery Program." https://www.masssave.com/residential/rebates-and-incentives/connected-solutions
9. Database of State Incentives for Renewables & Efficiency (DSIRE). https://www.dsireusa.org/