Solar + EV integration
Charger power, timing, and your solar window build an hour-by-hour picture. See exactly how much of that charging window overlaps with actual solar production.
How it works
Step 1
Check your charger's nameplate or your vehicle's onboard charger spec for an accurate kW figure.
Step 2
Run the tool multiple times with different start hours to see which schedule captures the most solar overlap.
Step 3
Most EVs and Level 2 chargers support scheduled charging, letting you lock in your ideal solar-overlapping window automatically.
The exact same charger running for the exact same number of hours can have dramatically different solar overlap depending purely on when it starts. In one typical comparison, a 7.2 kW charger running 4 hours starting at 9am captured about 91% solar overlap, while the identical charger running overnight starting at 10pm captured essentially none, illustrating just how much scheduling alone can affect self-consumption, a factor EIA electricity data reflects in time-of-use rate design.
This tool models solar production as a simplified curve that peaks at your specified output during the middle of your solar window and tapers toward zero at the start and end times you provide, approximating a typical clear-day production shape similar to NREL's PVWatts modeling. Actual solar production varies with weather, season, and cloud cover, so this represents a reasonable typical-day estimate rather than a precise forecast for any specific date.
The overlap percentage this tool calculates measures how much charging energy coincides in time with hours of solar production, which is a useful proxy for potential self-consumption. It doesn't guarantee that exact amount of solar actually gets used for charging, since that also depends on whether your system's total output during those hours, checked with the output vs usage gap analyzer, is sufficient to cover both the charger and any other simultaneous household electricity use.
Before locking in a scheduled charging routine on your vehicle or charger, running a few different candidate start times through this tool can reveal which window genuinely captures the most solar overlap for your specific charger power and solar production window. This kind of quick comparison is often more useful than guessing at an ideal time intuitively.
Once you've found a promising charging window, check the charging schedule optimizer tool for broader scheduling strategy, or the charging cost offset percentage calculator to translate this overlap into an actual dollar savings figure. Worth pairing this with the peak shaving savings estimator.
Questions
For the same 7.2 kW charger running 4 hours, starting at 9am gave about 91% solar overlap in a typical example, while the identical charger running overnight starting at 10pm gave 0% overlap. Charging window timing has an enormous effect on how much of that energy actually comes from solar versus the grid.
This tool uses a simplified curve peaking at your specified peak output during the middle of your solar production window, tapering toward zero at sunrise and sunset. Real solar production varies with weather and season, so this represents a typical clear-day shape rather than your exact production on any specific day.
The overlap percentage shows how much of your charging energy, hour by hour, coincides with hours when solar is actively producing, which is a reasonable proxy for how much of that charging could be self-consumed solar rather than grid electricity. It's not a guarantee of actual solar offset, since that also depends on whether your system is producing enough total power to cover both charging and other household use simultaneously.
Yes, this is exactly the kind of comparison this tool is built for. Try a few different start times with your actual charger power and solar window to see which schedule captures the most solar overlap before setting up a scheduled charging routine on your vehicle or charger.
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