How many solar panels to charge a Tesla or other EV? For a typical driver doing about 12,000 miles a year, the answer is usually around 6 to 10 panels of 400W added to your home system. The exact number depends on how far you drive, how efficient the car is and how much sun you get.
Solar Panels to Charge a Tesla: Step by Step
- Annual miles: e.g., 12,000
- Efficiency: many EVs use about 0.25-0.35 kWh per mile at the wall, including charging losses (check your car’s display and the EPA label)
- Annual kWh: 12,000 × 0.28 ≈ 3,360 kWh
- System size: 3,360 ÷ your PVWatts kWh per kW
- Panels: system watts ÷ 400
| Miles per year | kWh per year (at 0.28/mi) | Average sun (1,350 kWh/kW) | 400W panels |
|---|---|---|---|
| 8,000 | ~2,240 | ~1.7 kW | ~5 |
| 12,000 | ~3,360 | ~2.5 kW | ~7 |
| 15,000 | ~4,200 | ~3.1 kW | ~8 |
| 20,000 | ~5,600 | ~4.1 kW | ~11 |
These are estimates. Sunnier areas need fewer panels; cloudier areas need more.
Daytime vs Nighttime Charging
Most EVs charge overnight, when solar isn’t producing. That’s fine with net metering, since daytime exports offset nighttime imports. Under net billing or TOU rates, midday charging (if the car is home) or a home battery captures more value.
Charger Options
- Level 2 (240V) charger, typically on a 40-60A circuit
- Solar-aware chargers that follow surplus production
- Some inverter and battery systems coordinate EV charging
Should You Use a Home Battery to Charge Your EV?
A 13.5 kWh battery holds roughly 40-50 miles of driving. It’s usually better for evening home loads, with the EV charging from solar directly or from the grid off-peak.
Cost
At Berkeley Lab’s 2024 median of about $4.0/W, adding 2.5 kW costs roughly $10,000 before incentives if added at install time. Compare with what you’d pay the utility for the same kWh.
Adding Panels Later
If you already have solar and then buy an EV, adding panels later is possible but can mean a new permit, new interconnection review and possibly a second inverter. It’s usually cheaper to size for a planned EV in the original install. Ask your installer whether your inverter has room for extra panels.
Find Your Car’s Real Efficiency
The EPA label lists efficiency in kWh per 100 miles, and fueleconomy.gov lists it for every EV by model year. The label figure includes charging losses from the wall. Your car’s trip meter shows real-world use, which changes with speed, temperature and climate control. Winter driving often uses noticeably more energy.
| Efficiency | kWh per mile | kWh for 12,000 miles | 400 W panels at 1,350 kWh/ |
|---|---|---|---|
| 25 kWh/ | 0.25 | 3,000 | about 6 |
| 28 kWh/ | 0.28 | 3,360 | about 7 |
| 33 kWh/ | 0.33 | 3,960 | about 8 |
| 40 kWh/ | 0.40 | 4,800 | about 9 |
Smaller efficient sedans sit near the top rows, and larger SUVs and trucks near the bottom. Look up your exact model.
Worked Example: Panels by Location
For 12,000 miles at 28 kWh/100 mi (3,360 kWh a year), using example PVWatts outputs:
| Location type | kWh per kW (example) | Added kW | 400 W panels |
|---|---|---|---|
| Cloudy, northern | 1,100 | 3.1 kW | 8 |
| Average | 1,350 | 2.5 kW | 7 |
| Sunny Southwest | 1,600 | 2.1 kW | 6 |
Panel counts are rounded up. For the whole-home sizing method, see how many solar panels do I need.
Worked Example: Daily Charging and Charger Size
3,360 kWh a year is about 9.2 kWh a day. A Level 2 charger on a 40 A circuit draws up to 32 A continuous (the NEC sizes EV charging as a continuous load at 125%), which at 240 V is 32 × 240 = 7.7 kW. That covers a day’s 9.2 kWh in about 1.2 hours. Tesla’s Wall Connector can deliver up to 48 A on a 60 A circuit, or 11.5 kW at 240 V.
| Charger | Circuit | Continuous amps | Power at 240 V | Time for 9.2 kWh |
|---|---|---|---|---|
| Level 1 (120 V outlet) | 15–20 A | 12 A | 1.4 kW | about 6.4 h |
| Level 2 | 40 A | 32 A | 7.7 kW | about 1.2 h |
| Level 2 | 60 A | 48 A | 11.5 kW | about 0.8 h |
Level 1 at about 1.4 kW is closer to what a few panels make at midday, which can work well for solar-matched charging if the car is home. See watts to amps and 120V vs 240V split phase.
Worked Example: Solar vs Grid Cost per Mile
Using the EIA 2024 U.S. average residential price of about 16.5 cents/kWh, and LBNL’s 2024 median installed price of $4.0/W (illustrative):
- Grid charging: 3,360 kWh × $0.165 = about $554 a year, or about 4.6 cents per mile.
- Added solar: 2.5 kW × $4,000 per kW = $10,000. Over 25 years at 0.5% yearly degradation, those panels make about 79,000 kWh, or about 12.6 cents per kWh before financing.
At the national average rate, grid charging is cheaper per kWh than the added panels in this example. At higher rates, such as 30 cents/kWh, the panels come out ahead. Under net billing, timing matters too. See net metering vs net billing and solar payback period.
Smart Charging Options
- Scheduled charging: set the car or charger to start at midday on weekends or work-from-home days, or overnight off-peak on a TOU plan.
- Solar-surplus charging: some chargers and home energy systems adjust charging current to match excess solar.
- Battery coordination: some home batteries and gateways can limit EV charging during outages to protect backup reserve. See critical loads panel explained.
Step-by-Step: Adding EV Load to a Solar Plan
- Look up your EV’s kWh/100 mi and your yearly miles.
- Calculate yearly kWh and add it to your home’s use.
- Size the array with PVWatts.
- Plan a Level 2 circuit and check main panel capacity (the solar breaker and EV circuit both need space).
- Decide on charge timing for your rate plan.
- Ask installers to quote with and without the EV load. See solar for 1,000 kWh per month.
FAQ
How many solar panels to charge a Tesla Model 3?
Commonly around 6-8 panels of 400W for 12,000 miles a year in average sun.
Can I charge my EV directly from solar panels?
Not without an inverter and charger. Most homes charge through the home system.
Is it worth adding solar for an EV?
Often, if your electricity rate is high and you have roof space.
How many kWh does it take to charge a Tesla?
It depends on the model and battery size. Divide miles driven by the car’s miles per kWh, or multiply miles by its kWh per mile from fueleconomy.gov. Charging losses are included in EPA label figures.
Can solar charge an EV on a cloudy day?
Yes, at reduced output, and grid-tied systems simply draw the rest from the grid. Under net metering, sunny-day surplus offsets cloudy-day charging.
Sources: NREL PVWatts; NREL Solar program; U.S. DOE/EPA fueleconomy.gov EV efficiency data; Lawrence Berkeley National Laboratory, Tracking the Sun (2025 update); DOE/EPA fueleconomy.gov; Tesla Wall Connector specifications; EIA average residential price 2024; NFPA 70 (NEC) Article 625. Accessed Oct 2026.
Related: Mokin 140W GaN Charger Review, EcoFlow Delta 3 Max Home Backup