The short answer
If you have solar panels, the cheapest time to charge your EV is the middle of the day, while your roof is making power. Charging in the evening can cost you well over $1,000 a year, even with a roof full of panels.
Why? It comes down to what your utility pays you for solar power, and what it charges you when you buy power back. The easiest way to see it is to follow your solar power through a single day.
12 noon: your panels are at their best
The sun is high and your panels are making lots of power. Your home uses what it needs, like the fridge and the air conditioning. If your car is plugged in, it takes the rest. That power costs you nothing extra, because it never leaves your house.
But if your car is at work, that extra power goes out to the grid. Under California's NEM 3.0 rules (for solar systems that applied to connect on or after April 15, 2023), your utility pays you only around 5 cents per kWh for it.
6 PM: you get home and plug in
The sun is going down, so your panels make little or nothing. Your car has to charge from the grid, and you're now in the evening peak, the most expensive time of day. On PG&E's EV2-A plan, peak power (4 to 9 PM) costs about 54 cents per kWh in summer and 41 cents in winter, or about 45 cents averaged over the year.
So you sold your power for about 5 cents at lunchtime and bought it back for around nine times as much at dinnertime.
After midnight: the cheap hours
If you wait, things get better. On the same EV2-A plan, power after midnight costs about 23 cents per kWh all year. That's still much more than the 5 cents you got for your solar, but it's about half the evening price.
What that adds up to in a year
We compared the three charging times for the same car under California's NEM 3.0 rules. The car is a 2024 Tesla Model Y Long Range (29 kWh per 100 miles, EPA), driving 35 miles a day. That takes about 10.2 kWh a day. There's no home battery.
The evening and overnight rows earn the 51¢ export credit because the day's solar goes to the grid. In the midday row, the car uses that solar instead, so there's no credit and nothing to pay. Rates: PG&E EV2-A, about 45¢ peak (yearly average) and 23¢ after midnight; export credit about 5¢.
| When you charge | Credit for exported solar | Paid to the grid | Net cost per day | Net cost per year |
|---|---|---|---|---|
| Midday, straight from your panels | $0 (you used it yourself) | $0 | $0 | $0 |
| Evening peak, 4–9 PM | +$0.51 | $4.59 | $4.08 | about $1,490 |
| After midnight, on an EV rate plan | +$0.51 | $2.35 | $1.84 | about $670 |
What the numbers mean
Two things jump out. Charging in the evening costs about $1,490 a year, even though you have solar. And simply waiting until after midnight saves about $820 a year, without buying anything.
One honest caveat: in winter, your panels make less, so on short, cloudy days midday charging may not cover the whole charge. The rest comes from the grid. Our winter guide covers how big that gap gets.
Does this apply to you?
It depends on how your utility pays you for the solar you send to the grid. Look for a section called "net metering" or "solar" on your bill or your utility's website.
If you get full 1:1 net metering, your utility credits you the full retail price for every kWh you export. Your meter basically runs backwards at noon and forwards at night, and the two cancel out. Day or night charging costs about the same.
If you get a lower export credit (often called net billing), you're in the same boat as California. Every kWh your car takes straight from your roof saves you money.
More and more states and utilities are moving to the second kind. If you're not sure which you have, ask your utility or look it up on DSIRE (dsireusa.org).
Five ways to shift more charging to the daytime, or at least to cheaper hours
1. Set a charging schedule. Most EVs and home chargers let you choose when charging starts. If you can't charge at midday, set it to start after your utility's peak ends, or after midnight on an EV plan. It's free and takes two minutes.
2. Switch to an EV rate plan. Many utilities have special EV plans with cheap overnight power. On PG&E, that's EV2-A.
3. Use your home days. If you work from home on some days, or have the car at home on weekends, plug in at mid-morning. Your car doesn't need to charge every day.
4. Get a solar-aware charger. These chargers slow down or speed up to match your extra solar, so the car uses only what your roof makes. Tesla's Charge on Solar does the same thing, but it needs a Powerwall at home.
5. Add a home battery. A battery stores your midday solar so you can charge the car with it in the evening. It works, but it costs around $13,500, so read our home battery guide before you decide.
An example: David in Phoenix
David lives in Phoenix, Arizona, and gets his power from APS. He drives a 2024 Hyundai Ioniq 5 Long Range RWD (30 kWh per 100 miles) to the office three days a week and works from home on Thursdays and Fridays. Altogether he drives about 150 miles a week, which takes about 45 kWh, or about 2,340 kWh a year.
When he first got solar, he plugged in every evening when he got home around 6 PM. On APS's time-of-use plan, that's right in the peak window (4 to 7 PM on weekdays), when power costs about 33 to 34 cents per kWh. That came to about $780 a year in grid power for charging. His daytime solar still went to the grid and earned about $130 a year in export credits (about 5.5 cents per kWh for new APS solar customers), so his net cost was about $650 a year.
Then he changed one habit. On office days, he doesn't plug in at all, since his car has plenty of range for three days of driving. On Thursday and Friday he plugs in around 10 AM, and most of the charge comes from his own roof. He now pays close to nothing for charging; the main cost is the roughly $130 a year in export credits he no longer earns.
Even if he'd only waited until after 7 PM, when APS off-peak power is about 12 cents, he'd have paid about $280 a year, or about $150 after his export credits. Daytime charging did better still, and he didn't have to buy a home battery.
One more thing David noticed: in winter, APS has a "super off-peak" price of about 3.5 cents per kWh between 10 AM and 3 PM on weekdays. So on cloudy winter days, midday grid power is nearly as cheap as his own solar.
David is an example, not a real customer.