Transitioning from a gas-powered car to an electric vehicle (EV) is a smart move, but charging that EV with home solar panels is where the real financial magic happens. The Solar-to-EV Savings Calculator helps you visualize exactly how much money you keep in your pocket every year by bypassing the gas pump and driving on sunshine.

How to use the Solar-to-EV Savings Calculator

This tool removes the guesswork from EV charging by using the “eGallon” concept—which represents the cost to drive an EV the exact same distance you could drive a standard car on one gallon of gasoline.

Here is the math behind the curtain:

• The Gas Baseline: It divides your annual mileage (12,000 miles) by your gas car’s MPG to find how many gallons you buy a year, then multiplies that by local gas prices.
• The Solar Baseline: It divides that same annual mileage by your EV’s efficiency (miles per kWh) to find the total electricity needed. It then multiplies that by your solar Levelized Cost of Energy (LCOE).
• The Result: By subtracting the solar cost from the gas cost, it reveals your true annual savings and generates a visual breakdown of your fueling expenses.

How to Use This Tool

Follow these simple steps to calculate your custom savings:

1. Set Your Gas Baseline: Adjust the sliders for your local gas price and the MPG (miles per gallon) of the gas car you are comparing against.
2. Choose Your EV Specs: Use the convenient preset dropdown to select the type of EV you own (or plan to buy). You can also manually adjust the efficiency in miles per kWh.
3. Input Your Solar Cost: Enter your home solar Levelized Cost of Energy (LCOE). If you aren’t sure what this is, leaving it at the US average of $0.06/kWh is a highly accurate starting point.
4. Review Your Savings: Scroll down to the dashboard to instantly see your custom “eGallon” price, your total annual savings, and a clear visual comparison of your fueling costs.
5. Export Your Report: Click the “Download PDF” button to save or print a clean copy of your results.

Frequently Asked Questions (FAQs)

Is it really cheaper to charge an EV with solar panels than buying grid electricity?

Yes. While charging an EV from the standard utility grid is almost always cheaper than buying gasoline, utility rates are constantly rising. By charging your EV using a home solar system, you lock in a fixed, ultra-low rate for your electricity (often between $0.05 and $0.08 per kWh), maximizing your EV savings and insulating yourself from inflation.

What exactly is an “eGallon”?

The eGallon is a term created by the Department of Energy to help consumers compare EV charging costs to gas prices. It represents the cost of fueling an electric vehicle to drive the exact same distance that a similar gas-powered car could travel on one gallon of gasoline.

What is Levelized Cost of Energy (LCOE)?

LCOE is the truest way to measure the cost of solar power. You calculate it by taking the total net cost of your solar panel installation and dividing it by the total estimated kilowatt-hours (kWh) those panels will produce over their 25-year lifespan. This gives you a steady “cents per kWh” rate to compare against your local utility company.

How many solar panels does it take to charge an electric car?

This depends on your driving habits and your EV’s efficiency. The average American drives 12,000 miles a year. For a highly efficient EV (like a Tesla Model 3), this requires about 3,400 kWh of electricity annually. Depending on the wattage of the panels and your local sun exposure, you typically need to add 7 to 10 standard solar panels to your array to completely cover your EV driving.