Almost every residential customer in California is now on a time-of-use rate, and most people were moved onto one without ever choosing it. The result is a bill where the same kilowatt-hour costs a very different amount depending on when you used it, and where two neighbours with identical annual consumption can pay noticeably different amounts purely because of when their appliances happen to run.
Understanding your rate schedule is the highest-value hour you can spend on your electric bill, and it costs nothing. It also determines whether solar alone makes sense for your house or whether solar with storage is the better answer, which is why we start every conversation here rather than with equipment. If you want the questions we get asked most often about both utilities, our FAQ covers them.
What a time-of-use rate actually is
A time-of-use schedule divides the day into pricing periods and charges a different rate per kilowatt-hour in each one. The periods change between summer and winter, and often between weekdays and weekends. Layered on top of that are charges with nothing to do with when you use power at all, which is why a solar system that offsets your entire energy consumption still leaves you with a bill. When you look at your statement, separate these components before you do anything else.
- The energy charge, priced per kilowatt-hour and varying by time period. This is the part solar and load shifting actually affect.
- Delivery and distribution components, which pay for the poles, wires and substations serving your address.
- Fixed or minimum charges that apply every month regardless of consumption.
- Non-bypassable charges, which a solar customer pays on energy drawn from the grid no matter what.
- Seasonal definitions, because summer and winter periods are defined by the tariff, not by the weather outside your window.
Why four to nine in the evening decides your bill
The peak window sits in the late afternoon and evening because that is when the grid is most strained, and it is most strained then for a reason that is obvious once you have lived here. Solar generation across the state falls off sharply as the sun drops, while demand does not fall with it. In the Coachella Valley the air conditioning load is still near its maximum at six in the evening, because the structure of the house is saturated with heat that took all day to accumulate and does not leave the moment the sun goes down.
So the utility faces its hardest hours precisely as solar output collapses, and it prices those hours to reflect that. For a valley home, the peak window can account for a disproportionate share of a summer bill despite covering a small slice of the clock. That concentration is the entire reason load shifting works. Moving a load out of five hours a day is a manageable change with an outsized effect, and it is available to you before you spend a dollar on hardware.
SCE and IID are not the same utility
Which utility serves you depends on your address, and the two operate under entirely different rules. Southern California Edison is regulated by the state commission, and its residential customers choose among several time-of-use schedules, including a widely used option with a four to nine peak and a schedule aimed at households that own an electric vehicle, a battery or a heat pump. New solar customers on SCE fall under the state's net billing tariff, which credits exported energy at hourly avoided-cost values rather than at the retail rate.
Imperial Irrigation District is a municipal utility governed by its own board. It sets its own rate structures and runs its own arrangement for solar customers, and its rates have generally sat below SCE's, which changes the size of the gap between peak and off-peak pricing and therefore the value of shifting a load. If IID serves your address, do not apply advice written for SCE customers to your bill without checking first. Our service areas page covers which communities across the valley we work in.
Load shifting: what actually moves
Not every load can move, and pretending otherwise leads people into a schedule they abandon within a week. Sort your consumption into what shifts easily, what shifts with a piece of equipment, and what does not shift at all. Then move the first two categories and stop worrying about the third.
- Moves easily with a timer or a habit: dishwasher, laundry, pool filtration, spa heating, irrigation on a pump.
- Moves with equipment: EV charging on a scheduled charger, water heating with a heat pump unit and a timer, pre-cooling with a thermostat that supports multiple setpoints.
- Moves partially: air conditioning, through pre-cooling and setpoint drift rather than through switching it off.
- Does not move: cooking dinner, lighting, refrigeration, and anything else tied to when your family is actually home.
People assume load shifting means living differently. For most households it means changing four settings once and never thinking about it again. The dishwasher does not care what time it runs.
Where storage fits
A battery is a machine for moving energy through time. Charge it from your array when production is high and prices are low, discharge it through the evening peak, and you have converted cheap midday energy into expensive evening energy without changing anything about how you live. Under net billing that is the main financial argument for storage, and it is a stronger argument here than in a milder climate because our evening load is so large. Two numbers describe a battery and people usually ask about only one: capacity in kilowatt-hours tells you how long it can carry a load, while continuous power in kilowatts tells you how much it can carry at any one moment. A battery with plenty of capacity but modest power output will not start a large air conditioning compressor no matter how full it is. We cover both sides of that on our storage page.
A week to start with
- 01Find your rate schedule name on the bill and look up its actual peak and off-peak periods, including the seasonal definitions.
- 02Download a month of interval data from your utility account and look at where your consumption sits across the day.
- 03Move pool filtration and any irrigation pump entirely out of the peak window.
- 04Set the dishwasher and the laundry to run late in the evening or overnight rather than straight after dinner.
- 05Schedule EV charging to begin after the peak window closes, not the moment you plug in.
- 06Build a thermostat schedule that pre-cools before the window and holds a higher setpoint through it.
- 07Compare the next bill against the same month last year, and only then decide whether storage is worth modelling.
Do that much and you will know more about your own consumption than most homeowners ever learn, and you will be able to judge a solar proposal on its merits instead of on its cover page. If you want the effect of these changes modelled against your own history, the savings calculator is a starting point, and we can go through the numbers with you whenever you are ready.
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