Solar + EV Planner

An average US driver covers about 12,000 miles per year. At 3.5 mi/kWh and 10% charging losses, that's roughly 3,800 kWh per year at the wall. In a sunny state with 5.5 peak sun hours, you need about 2.4 kW DC of solar — six to eight 400 W panels.

Heavier drivers, less efficient EVs (trucks, large SUVs), or cloudier states all push the panel count higher. Use the calculator above with your actual numbers — the math scales linearly with miles and inversely with efficiency.

Once your solar panels are paid off, charging from solar is essentially free — just a small share of inverter and panel maintenance spread across the kWh. Grid charging costs your utility rate per kWh divided by your EV's efficiency.

At 14¢/kWh and 3.5 mi/kWh that's about 4¢/mile from the grid versus less than 1¢/mile from owned solar. Both beat gasoline by a wide margin — even at $3.50/gallon, a 28 MPG gas car costs 12.5¢/mile.

Not if your utility offers net metering at or near the retail rate. Your daytime solar exports get credited against your overnight charging draws — the grid effectively acts as your battery for free.

If your utility uses export rates well below retail (California NEM 3.0 credits exports at roughly 25% of retail), a home battery starts to pay back faster, especially paired with time-of-use rates. Our battery sizing tool walks through a full sizing pass.

Yes. The federal Investment Tax Credit applies to the full installed cost of any residential solar system you own through 2032 — including capacity added specifically to cover EV charging. The credit doesn't care what the kWh are used for; it cares that you own the system.

A separate federal EV tax credit (up to $7,500) may apply to the car itself if income, price, and assembly requirements are met. The two credits stack — they cover different things.

Size for the car's annual usage, not the charger's peak draw. A 7.2 kW Level 2 charger can pull power faster than your solar produces in the moment, but it only runs a few hours a day — the annual kWh is what determines panel count.

Net metering smooths the moment-to-moment mismatch between when the sun shines and when you plug in. If you're fully off-grid, sizing changes — see our off-grid calculator.

Cold weather hits both sides: EV efficiency drops 20–40% in winter (battery heating, cabin heat, denser air resistance), and solar production drops with shorter days and lower sun angles. We use annual averages, so winter dips and summer peaks roughly cancel for a fixed rooftop system.

If you live somewhere with brutal winters and you charge mostly overnight, bump the miles-driven figure up 10% or efficiency down 10% to stress-test the math. Snow-covered panels also lose a few weeks of production each year — typically less than 5% annually.