Savings and payback

Savings with EV charging included

See how much of your EV's charging cost your existing solar system can absorb, especially if it was producing more than your household used on its own.

For planning purposes only, not financial or tax advice; confirm figures with a licensed installer or tax professional before making a purchase decision.

Your numbers

1 Household and solar
Your annual usage before adding any EV charging.
Use the production figure from the solar savings calculator if needed.
2 Your EV
Most EVs run 3 to 4 miles per kWh. Check your vehicle's efficiency rating for an exact figure.

How it works

Three steps to your EV impact

Step 1

Enter your household usage and solar production

Use your usage before adding EV charging, and your system's annual production from the solar savings calculator if needed.

Step 2

Add your EV's annual mileage and efficiency

Most EVs run 3 to 4 miles per kWh. Check your vehicle's specs or trip computer for a more exact figure. Charging overnight instead of midday? The battery vs without battery comparison covers that gap.

Step 3

See how much spare solar the EV soaks up

If your system was producing more than your household needed, the tool shows how much of that spare production now offsets EV charging instead of being exported at a lower credit rate.

Understanding solar and EV charging together

When adding an EV genuinely increases savings

In one example, a system producing 9,490 kWh a year against 7,000 kWh of household usage was exporting the extra 2,490 kWh at a lower credit rate. Adding a 12,000 mile-a-year EV, which uses about 3,429 kWh annually at 3.5 miles per kWh, soaked up that spare production instead of letting it go to the grid, adding $398 a year in savings compared to the household alone. The US Department of Energy's homeowner's guide to going solar walks through the same decision step by step.

When an EV adds cost with no offset

If your system's production was already fully self-consumed by your household before adding an EV, there's no spare production left to absorb the new load. In that scenario, EV charging is added cost with no help from your existing system, and upsizing the system or adding panels becomes worth considering, or see the savings calculator for high usage homes for that broader scenario. If an EV is in your plans, the ev road trip charging cost vs home solar savings adds its charging load to the sizing math.

Why charging timing matters

Charging your EV during daylight hours lets it draw directly from solar production as it's generated. Charging overnight instead pulls from the grid unless you have battery storage to bridge the gap. See the battery vs without battery comparison for how storage changes this picture, or the time of use rate savings calculator if your utility prices power differently by time of day. For background on how solar power is generated, the solar explainer from the US Energy Information Administration is a solid starting point.

Estimating your EV's usage

Divide your expected annual mileage by your EV's efficiency in miles per kWh. Most electric vehicles run 3 to 4 miles per kWh, though this varies by model, driving style, and climate. Check your vehicle's trip computer for a more precise figure specific to your driving. The system size by annual kwh usage is the quickest way to check whether the system size behind this estimate fits your roof and usage.

Questions

Frequently asked

Only if your system was producing more than your household used on its own. In one example, a system offsetting 9,490 kWh a year against 7,000 kWh of household usage was exporting the extra 2,490 kWh at a lower credit rate. Adding a 12,000 mile-a-year EV soaked up that excess, adding $398 a year in savings.

If your system's production was already fully self-consumed before adding an EV, the EV's charging cost is added on top with no offsetting benefit from your existing system, since there's no spare production left to cover it. In that case, a bigger system or added panels may be worth considering.

Divide your expected annual mileage by your EV's efficiency in miles per kWh, typically 3 to 4 miles per kWh for most electric vehicles. A car driven 12,000 miles a year at 3.5 miles per kWh uses about 3,429 kWh annually.

Yes. Charging during daylight hours lets your EV use solar production directly as it's generated. Charging overnight draws from the grid instead, unless you have battery storage or scheduled off-peak charging. The time of use rate savings calculator covers how charging timing interacts with rate plans.

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