Your battery, hour by hour

Your battery buys power when it's cheap and uses it when it's not.

One day on PG&E EV2-A, told in five chapters. Scroll through it and watch what the house buys from the grid with and without a battery, all the way into the 4 PM-9 PM peak at $0.55 per kWh.

Modeled on PG&E EV2-A
12:00 AM
$0.12/kWh

1 / 6Overnight12 AM-6 AM

The house sleeps on cheap power.

Overnight is the lowest price of the day on PG&E EV2-A: $0.12 per kWh. The fridge hums, the chargers top off, and the battery holds what it stored yesterday. There is nothing to win here yet, so it waits.

Without battery
With battery
Saved so far

Grid electricity bought since midnight, PG&E EV2-A, summer.

Battery holding4.8 kWh36% of 13.5 kWh, waiting for tomorrow's peak

2 / 6Sunrise6 AM-8 AM

The sun comes up and your panels take the house.

Around 6 AM the panels wake up. By 8 AM they cover the morning load on their own: coffee, showers, the first EV miles. The grid line goes quiet and the meter nearly stops. Rates are still low, so the battery stays out of it.

Without battery
With battery
Saved so far

Grid electricity bought since midnight, PG&E EV2-A, summer.

Panels covering0% of the house0.0 kW of sun vs 0.8 kW of load, 0.8 kW from the grid

3 / 6Battery charges8 AM-4 PM

Midday surplus fills the battery instead of leaving for pennies.

From 8 AM the panels make more than the house can use. Without a battery that surplus is exported for about $0.04 per kWh. With one, it goes into storage for the $0.55 hours that start at 4 PM. Same electrons, roughly 14 times the value.

Without battery
With battery
Saved so far

Grid electricity bought since midnight, PG&E EV2-A, summer.

Stored so far0.0 kWhWould have exported at $0.04. Worth $0.55 per kWh at 4:00 PM.

4 / 6Peak pricing4 PM-9 PM

Peak pricing hits $0.55 per kWh. The battery runs the house.

Between 4 PM and 9 PM you would normally buy your most expensive electricity of the day, about 4.6 times the overnight price. Instead the battery carries the evening load and the grid barely sees you.

Why the spike: rooftop solar pushes midday grid demand down, then at sunset homes turn on ovens, air conditioning and chargers all at once while solar disappears. Serving that steep evening ramp is expensive, so utilities price it that way. Your panels cannot help at 7 PM. Stored solar can.

Noon6 AM$0.55 peaksolar bellyevening ramp
Grid demand net of rooftop solar. The steep evening ramp is what you pay for in the peak window.
Without battery
With battery
Saved so far

Grid electricity bought since midnight, PG&E EV2-A, summer.

Peak load carried by the battery0.0 kWh$0.00 of $0.55 power you did not buy, and counting

5 / 6Evening9 PM-12 AM

Prices fall. The gap is your savings.

After 9 PM the rate drops back to $0.18 per kWh and the grid is cheap again. The battery is done for the day, and tomorrow it does the same thing. The difference between the two meters below is what one day on PG&E was worth.

Without battery
With battery
Saved so far

Grid electricity bought since midnight, PG&E EV2-A, summer.

$5.09 today. Every day like this one adds up to$1,733 a yearAt this summer pace on PG&E, net of export credits. Directional model, not a quote.

6 / 6How it saves moneySummer day, PG&E EV2-A

Two ways a battery earns. One does the heavy lifting.

Self-powering is the workhorse: store solar that would export for $0.04 and use it in place of $0.55 peak power. Smart export is the second mode, for markets where a utility pays a premium for evening exports. That value is market-dependent, so the dependable case is still running your own house through the peak.

Without battery$5.83
With battery$0.73
Saved today$5.09
A year of days like this$1,733$5.09 a day at this summer pace on PG&E. Winter days earn less; the season toggle shows how much.

Self-powering

$0.55/kWh

The battery runs the house while the price is highest. Stored midday solar replaces peak power one kWh at a time; that is where $5.09 of today's $5.83 bill went.

Smart export

$0.18/kWh

When a utility pays a premium for evening exports, the battery can sell automatically. That value is market-dependent, so the dependable base case is still covering your own peak.

12:00 AM$0.12/kWhOff-peak overnight
Home battery energy flow diagramSun and panels, home, battery, and grid nodes with power flow lines that change with the hour of the day.Sun / panels0.0 kW nowHome0.8 kW load36%Battery13.5 kWhGrid0.8 kW import
Drag to scrub
Modeled on PG&E EV2-A

Assumptions: 8 kW solar, 13.5 kWh battery, representative household load, and rounded period prices from the selected rate bundle. Directional model, not a quote.

By season

Solar battery savings by season on PG&E

A battery does not earn the same amount every day. Summer has more solar to store and a wider evening spread. Winter still shifts energy, but the numbers narrow. The deck above is playing the summer schedule.

Summer day on PG&E EV2-A

Summer peak 4-9 PM

4 PM-9 PM
$0.55$0.12Noon4 PM9 PM
$1,733/yrannualized pace
$0.55/kWhpeak import
$4.75modeled day delta

Winter day on PG&E EV2-A

Winter peak 4-9 PM

4 PM-9 PM
$0.38$0.13Noon4 PM9 PM
$1,524/yrannualized pace
$0.38/kWhpeak import
$4.18modeled day delta

Assumptions: 8 kW solar, 13.5 kWh battery, representative household load, and the period prices in the static rate bundle. Directional model, not a quote.

Backup, briefly

Battery backup during power outages

The same battery that shifts your evening load is backup power when the grid drops. It disconnects from the utility in a fraction of a second and runs the house from what it stored.

  • Islands automatically. No switch to throw; the lights blink once, then stay on.
  • Runs the essentials. Fridge, lights, Wi-Fi, outlets and phones typically last the night on one charged battery. Whole-home air conditioning takes more storage.
  • Recharges from the roof. With solar, the battery refills the next morning even if the grid is still down.
Grid offline, battery powering the homeGrid offlineBattery, islandedHome stays lit
Backup capacity depends on battery size and what you choose to keep on. Your proposal lists both.

Your utility

PG&E peak hours and TOU rates

Modeled on PG&E EV2-A. Every figure on this page uses this plan's buy rates, export credits, seasons, and peak window.

Not your utility? · ·

PG&E EV2-A

California net billing

California net billing makes evening self-consumption valuable because imports cost more than midday exports earn.

  • Summer peak (4 PM-9 PM)$0.55/kWh
  • Winter peak (4 PM-9 PM)$0.38/kWh
  • Lowest modeled import period$0.12/kWh
  • Highest modeled export credit$0.18/kWh
On flat or full-retail-credit rates, a battery is mostly about backup and control. Solar alone captures more of the bill savings when every exported kWh is credited like a retail kWh.

Personalize it

See what a battery earns at your address.

Your roof, utility, usage shape, and rate plan decide whether the battery is mainly savings, backup, or both.

  • Real bids from vetted local installers, priced on your actual roof
  • Battery sized to your utility rate and peak window, not a template
  • Your price locked online for 7 days. No in-home sales visit

Common questions

Solar battery savings FAQ

What is a time-of-use rate?

A time-of-use rate charges different prices at different hours. In the modeled rates on this page, electricity is cheaper in low-demand periods and more expensive during the evening peak window.

Do solar batteries save money?

Solar batteries can save money when your evening import price is higher than the value of exporting solar earlier in the day. They store low-value midday solar and use it later to avoid buying peak electricity. On flat or full-retail-credit rates, a battery is usually more about backup and control.

What happens under NEM 3.0?

Under California net billing, exported solar is often credited below the retail import price. That makes self-consuming stored solar in the evening more valuable than exporting excess solar cheaply at midday. The exact result depends on utility rate, export credits, usage shape, system size, and battery settings.

Can I add a battery to existing solar?

Often, yes. The right design depends on your inverter, electrical panel, available wall space, utility approval, and whether you want backup for selected circuits or a broader home backup design.

How long do solar batteries last?

A home battery is designed for daily cycling over a long service life, but the practical answer is in the warranty: term, energy throughput, retained capacity, chemistry, and installation conditions all matter.

When is electricity cheapest?

In this rate bundle, the cheapest import periods are overnight, midday, or both depending on the utility and season. The page model uses the selected rate periods directly, so the figures change when the utility or season changes.

What are peak electricity hours?

Peak electricity hours are the expensive windows when demand is high and solar production is falling. In the modeled California rates, that peak window is 4 PM to 9 PM. APS uses a shorter summer peak and a different winter peak in this bundle.