Solar + EV integration

EV charging schedule solar optimizer tool

Enter when your car is home and when your panels produce power. See exactly how much of your daily charging can realistically come from solar.

Your schedule and charging setup

1 Project details Optional
2 Your charging need
From your daily miles times vehicle efficiency, or check the EV charging load addition calculator.
Amps times volts, divided by 1000. A 40A/240V charger is 9.6 kW.
3 Solar array
Roughly when panels start meaningful output, typically 1 to 2 hours after sunrise.
Roughly when panels stop meaningful output, typically 1 to 2 hours before sunset.
4 Your at-home schedule
Use 9 for 9am, 17 for 5pm, 22 for 10pm, and so on.
If you're home all day, set arrival to 0 and departure to 24.

How it works

Three steps to finding your overlap

Step 1

Enter your daily charging need

Pull this from the EV charging load addition calculator if you haven't already worked it out.

Step 2

Add your solar production window

A rough estimate is fine here, since production ramps up and down gradually rather than switching on and off sharply. 8am to 6pm is a reasonable default for most of the continental US and Canada in summer.

Step 3

Enter when your car is actually home

Be honest about your real schedule, not an idealized one. If the overlap is small, the off-peak charging with battery tool shows how storage can help.

Understanding charging schedule overlap

Solar offset isn't just about array size

Most solar-for-EV sizing tools assume charging happens whenever solar is available, but that's only true if the car is actually home during those hours. A large, well-sized array generates power all day whether or not anyone is there to use it for charging, following a production curve tools like NREL's PVWatts model, so a mismatched schedule can leave a system's EV-charging potential mostly unrealized without either the battery storage size calculator's recommended capacity or a different charging strategy.

The classic mismatch: commuters who work outside the home

A driver who leaves for work before solar production ramps up and returns after it tapers off, a schedule reflected in typical residential demand patterns, has essentially no direct overlap with solar hours, even with a large array. In this common case, the two realistic options are adding a home battery to store daytime production for evening use, or charging at a workplace charger during the day, though the latter only counts as solar-powered if the workplace itself has solar.

Why remote and hybrid work changed this calculation for many households

A driver home during the day, even a few days a week, gets a meaningfully different result than a full-time commuter, since those days allow direct daytime charging that overlaps with peak solar output. Households with flexible schedules or a stay-at-home partner who can plug in the car midday often see much higher solar coverage than a two-commuter household with the same array size. Before you lock in a number, compare it with battery storage size calculator.

Weekend charging often closes the gap for weekday commuters

Even a driver with zero weekday solar overlap typically has the car home all weekend, which allows a large single-session solar charge to cover several weekdays' worth of driving if the battery has room. The weekend vs weekday charging tool looks at this pattern specifically.

Taking this result further

If your solar coverage is low due to a schedule mismatch, check the off-peak EV charging with solar battery tool to see how much storage would close the gap, or the workplace vs home charging tool if daytime charging away from home is an option. See the time of use rate savings calculator for the piece this tool doesn't cover.

Questions

Frequently asked

A large solar array can't charge your car with power it generates while you're away at work if the car isn't home to receive it. A commuter who leaves before sunrise and returns after sunset gets 0% direct solar coverage regardless of array size, unless a battery or workplace charging closes the gap.

A work-from-home schedule with the car parked at home during daylight hours can often reach 100% solar coverage on a modest daily charging need, since the full solar production window overlaps with charging time. This is one of the biggest practical advantages of remote work for EV owners with solar.

Yes, a home battery stores excess solar production during the day and releases it to charge the car overnight, which is exactly the scenario a commuter with no daytime overlap needs. Check the off-peak EV charging with solar battery tool to size that setup.

Only if the workplace charger is itself powered by solar, which this tool doesn't assume by default. Charging at work on grid power doesn't add to your home system's solar offset, though it can still reduce your home charging need and shift cost to your employer or a separate rate.

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