Solar Offset for EV Calculator

How much electricity does your EV actually use per year?

Before sizing a solar system, you need a realistic picture of your EV’s annual electricity consumption. According to the U.S. Department of Energy’s Fuel Economy data and real-world studies, the average electric vehicle consumes roughly 34.6 kWh per 100 miles (DOE, 2024). The Federal Highway Administration puts average annual U.S. driving at about 13,600 miles, which translates to approximately 4,700 kWh per year for a typical EV driver — before accounting for charging losses (typically 10–15%).

Efficiency varies significantly by vehicle class and model year. EPA Model Year 2024 ratings range from 53 MPGe for the least efficient trucks to 140 MPGe for the most efficient compact cars (DOE FOTW #1373, December 2024). Here are real-world annual consumption estimates for popular EVs at 12,000 miles/year:

Add 10–15% for real-world charging losses and cold-weather efficiency reductions. A compact sedan driver in a mild climate might need just 3,200 kWh/year from their panels; a truck owner in a cold northern state could need 6,500+ kWh. The calculator above uses your specific EV’s efficiency and your annual mileage to generate an accurate figure.

How many solar panels cover EV charging? A state-by-state look

The number of panels you need depends almost as much on where you live as on what you drive. NREL’s PVWatts tool quantifies this as “kWh produced per kW of installed solar per year” — a figure that ranges from about 1,050 in Seattle to over 1,800 in Phoenix (NREL, 2024). The table below shows how many 400W panels a typical EV driver (4,000 kWh/year) would need in representative states, assuming a south-facing roof at optimal tilt:

Source: NREL PVWatts V8 (2024). Values assume a fixed-tilt system at optimal angle, standard efficiency modules, and DC-to-AC ratio of 1.2. Panels sized at 400W each. Actual output varies by roof orientation and shading.

The math: sizing a solar system for your EV

Sizing solar for EV charging follows a straightforward formula, but the inputs matter. Here’s a worked example for a Chevrolet Equinox EV driver in Denver, Colorado driving 14,000 miles/year:

1. Annual electricity needed: 14,000 miles × 0.29 kWh/mile = 4,060 kWh. Add 12% for charging losses: 4,060 × 1.12 = 4,547 kWh/year.
2. Solar production in Colorado: Denver averages approximately 1,500 kWh of production per kW of installed solar per year (NREL PVWatts, 2024).
3. System size needed: 4,547 kWh ÷ 1,500 kWh/kW = 3.03 kW. Round up to 3.2 kW for a real-world buffer.
4. Panel count: 3,200W ÷ 400W per panel = 8 panels.
5. Installed cost: At the national average of ~$3.05/W (EnergySage, 2025), a 3.2 kW system costs approximately $9,760 before incentives.

If your EV has a different efficiency, or you drive more or fewer miles, the formula scales proportionally. The calculator on this page handles all of these steps automatically and applies your state’s actual NREL production figure. Note that the Section 25D federal residential solar tax credit expired December 31, 2025, so check your state’s incentive programs for additional savings.

Smart charging: aligning EV charging with solar production

Getting the solar sizing right is only half the story. When you charge matters as much as how much you charge. Solar panels produce the most power between 10 AM and 3 PM — often called the “solar window.” Scheduling your EV to charge during this window means you’re using electrons directly off your roof rather than pulling from the grid, which is the highest-value use of your solar production.

Studies show that load-shifting to peak solar hours can increase self-consumption rates by 15–40% without any additional hardware costs (SolarTechOnline, 2025). In 2025–2026, self-consuming solar is 3–6x more valuable than exporting it in most states: retail electricity rates run 25–45 cents/kWh while grid export (feed-in) tariffs often pay only 3–8 cents/kWh.

Most modern EVs and Level 2 chargers support scheduled charging:

• Tesla: Set a “Scheduled Charging” time in the app or via the touchscreen.
• Ford: Use the FordPass app to set a departure time and let the car schedule backward.
• GM (Chevy/GMC/Cadillac): myChevrolet app scheduled charging with off-peak and on-peak windows.
• Hyundai/Kia: Built-in departure time scheduling via the Bluelink or Kia Connect apps.
• Smart EVSE: Chargers like the ChargePoint Home Flex and Emporia Vue Smart Charger can schedule around utility TOU rates automatically.

If you can’t charge during the day (work, school), the next-best option is overnight super-off-peak charging — typically midnight to 6 AM — which avoids peak rates while leaving daytime solar production available for other home loads. See our EV Charging Cost Calculator to compare time-of-use vs. flat-rate electricity costs.

Net metering and how it affects the calculation

Net metering is the policy that lets you “bank” excess solar production with your utility and draw it back at night or on cloudy days. Under traditional 1:1 net metering, a kWh exported earns you the same credit as a kWh consumed — making the grid act like a free battery and making solar sizing straightforward.

But net metering policy has shifted significantly. California’s NEM 3.0 (effective 2023) cut solar export compensation from full retail (~$0.30/kWh) to $0.05–0.08/kWh. Florida moved to avoided-cost rates (~$0.05/kWh). Roughly 38 states plus Washington D.C. still have some form of net metering or net billing, but the trend toward lower export rates is clear (NC Clean Energy Technology Center, Q1 2025).

What this means for solar + EV sizing:

• States with strong net metering (New Jersey, Massachusetts, Illinois): You can size your solar system for annual production equal to annual EV consumption and trust the grid to balance timing differences.
• States with weak net metering (California, Florida): Size your system slightly smaller, pair it with a battery if budget allows, and prioritize daytime self-consumption over oversizing and exporting.
• States with no net metering (Alabama, Tennessee, some others): Battery storage is nearly mandatory to get full economic value from solar. An EV with V2H capability can partially fill this role.

Our calculator uses your state’s average electricity rate to estimate savings. For the most accurate ROI in weak-net-metering states, enter your self-consumption rate in the advanced settings.

Real-world ROI: solar + EV in high-rate vs. low-rate states

The economics of pairing solar with EV charging vary dramatically by state. The dominant factor is your retail electricity rate — every cent higher your rate, the faster your solar investment pays back. Here’s a comparison of a standard scenario (3.2 kW system, $9,760 installed, 4,000 kWh EV annual consumption) across four representative states:

Note: savings estimates assume 100% of solar production offsets EV charging at the retail rate, no net metering degradation, and 0.5% annual panel degradation. Electricity rates sourced from EIA Electric Power Monthly (2025). The Section 25D residential solar tax credit expired December 31, 2025 — these figures do not include it.

The takeaway: solar + EV is a slam-dunk investment in Hawaii and a strong one in California, New England, and other high-rate markets. In low-rate states like Washington and Louisiana, the electricity savings alone may not justify a system sized only for EV charging — but if you’re already sizing solar for whole-home coverage, the incremental cost to cover EV charging is modest. Use our Panel Upgrade Estimator to check whether your electrical panel can support a Level 2 charger before committing to a solar + EV installation plan.

V2H and V2G: using your EV as a battery

The most sophisticated pairing of solar and EVs goes beyond one-way charging. Bidirectional charging technology — V2H (vehicle-to-home) and V2G (vehicle-to-grid) — turns your EV’s battery pack into a massive, mobile energy storage system. A Ford F-150 Lightning carries up to 131 kWh of usable capacity: roughly 10x a typical home battery like the Tesla Powerwall.

As of 2026, EVs with confirmed bidirectional charging capability include:

Source: TMH Energy / Mobility House, EcoFlow, Electrek (2025–2026). Tesla vehicles do not currently support bidirectional export. Most new EVs from Volkswagen, GM, and Toyota are expected to add bidirectional capability in 2026–2028 model years.

In a solar + V2H setup, the workflow looks like this: solar charges the EV during the day; at night, the EV powers the home, avoiding peak grid rates. During a power outage, the EV provides backup power. In states with low net metering export rates (California, Florida), V2H can increase the effective value of solar production by 3–5x compared to exporting excess generation at avoided-cost rates. V2G programs, where your utility pays you to discharge during grid emergencies, are expanding — the first U.S. residential V2G power plant using Ford F-150 Lightning trucks went live in late 2025 (Electrek). Check with your utility for local V2G pilot enrollment.