Solar + EV Combined Savings Calculator
The ultimate green home calculator. Combine solar energy production with electric vehicle ownership to see your total annual savings, energy independence score, 25-year financial benefit, and CO2 reduction. This is the full picture of going clean energy.
Location & Current Energy Costs
Solar System
Electric Vehicle
Disclaimer
This calculator provides estimates for informational purposes only. Actual solar production, savings, and payback periods depend on site-specific conditions including local weather, roof condition, shading, equipment selected, installer pricing, utility rate structures, and policy changes. Always obtain multiple quotes from qualified solar installers and consult a tax professional for incentive eligibility. Results should not be considered financial advice.
Solar Annual Production
Solar kWh = System kW × Peak Sun Hours × 365 × 0.80 × Direction Factor
0.80 accounts for real-world system losses (inverter, temperature, wiring). Peak sun hours from NREL state data.
Home Energy Usage
Home Annual kWh = (Monthly Bill ÷ Electricity Rate) × 12
EV Annual Energy Need
EV kWh = Annual Miles ÷ Efficiency (mi/kWh)
After-Solar Grid Cost
Remaining Grid kWh = max(0, Total Need − Solar Production)
After Grid Cost = Remaining Grid kWh × Electricity Rate
CO₂ Reduction
Solar CO₂ = min(Solar kWh, Total kWh Need) × 0.86 lbs/kWh (EPA eGRID)
Gas CO₂ = (Annual Miles ÷ MPG) × 19.6 lbs/gallon
Energy Independence Score
Independence = (Solar Production ÷ Total Household Need) × 100%, capped at 200%
The Power of Combining Solar Panels with an Electric Vehicle
Solar panels and electric vehicles are individually compelling investments. Together, they create a synergy that can transform your household's energy economics and environmental footprint. A solar array that produces electricity for your home also produces electricity for your car — meaning the same investment that reduces your electricity bill also provides free transportation fuel. This combination represents the most complete vision of residential clean energy: generating your own power and using it for both home and transportation.
Understanding the Math of Solar + EV
The economics of combining solar and an EV are compelling at multiple levels. Consider a household in California with a $200 monthly electricity bill and driving 15,000 miles per year in a gas car. The annual energy cost is $2,400 in electricity plus approximately $1,750 in gasoline — a total of $4,150 per year. After installing an 8 kW solar system and switching to an EV, the electricity bill approaches zero (or becomes a small credit) and gasoline spending drops to zero as well. Annual savings of $3,500 to $4,500 per year fundamentally changes the financial math of both investments.
Battery Storage: Closing the Loop
The main limitation of solar + EV without battery storage is timing mismatch. Solar panels generate electricity during the day, but most EV charging happens overnight. Without storage, daytime solar excess is exported to the grid, and overnight EV charging draws from the grid. Battery storage systems like the Tesla Powerwall or Enphase IQ Battery bridge this gap — storing excess daytime solar to charge your EV at night with the electricity your panels generated during the day. In states with favorable net metering policies, the value difference between storage and no storage is smaller. In states with unfavorable export rates like California's NEM 3.0, battery storage becomes financially essential to capture full solar value.
Frequently Asked Questions
How much can I save by combining solar panels with an EV?
Combining solar panels with an EV creates a powerful synergy. Solar panels reduce or eliminate your electricity bill, while the EV eliminates gasoline costs. Together, a household can save $3,000 to $6,000 per year depending on location, system size, driving habits, and local electricity and gas prices. The solar array ideally generates enough electricity to power both the home and charge the EV, effectively giving you free transportation fuel.
Can solar panels fully power an electric vehicle?
Yes, in many cases. The average American drives about 15,000 miles per year, which requires approximately 4,000 to 5,000 kWh of electricity at typical EV efficiency. A 5 to 7 kW solar system in a sunny state can produce 7,000 to 10,000 kWh per year — enough to power both the home and charge an EV. In less sunny states, a larger system may be needed. Adding battery storage maximizes this by storing excess daytime solar energy for nighttime EV charging.
What size solar system do I need to power my home and EV?
To power a home and EV, add your home's annual kWh consumption to your EV's annual charging needs, then size your solar system to produce that amount. For example: 10,000 kWh home usage + 4,500 kWh EV charging = 14,500 kWh needed per year. In a state with 5 peak sun hours per day, you need: 14,500 ÷ (5 × 365 × 0.8) = approximately 10 kW system. This calculator estimates system sizing based on your current electric bill and driving habits.
What is the energy independence score?
The energy independence score represents the percentage of your total household energy needs (home electricity + EV charging) that your solar system produces. A score of 100% means your solar system produces at least as much electricity as you consume in total. Scores above 100% mean excess solar is exported to the grid under net metering. The score helps visualize how close you are to true energy independence.
Does battery storage improve the solar + EV combination?
Yes. Without battery storage, any excess solar generated during the day is exported to the grid, and you draw from the grid at night for EV charging. With battery storage, you can store daytime solar excess and use it for overnight EV charging — maximizing your solar self-consumption and reducing grid dependence. In states with poor net metering policies (like California's NEM 3.0 with lower export rates), battery storage is particularly valuable for capturing full value from solar production.
What is the payback period for solar + EV combined?
The combined solar + EV payback period depends on the net investment after considering both systems. Since the EV itself often costs more than the comparable gas vehicle but saves on fuel and maintenance, the EV portion has its own payback. The solar system has a separate payback of typically 6 to 10 years. Taken together, the combined investment is significant but the total annual savings — often $3,000 to $6,000 per year — can deliver a 10-year net benefit of $20,000 to $50,000 after recovering all costs.
How does the solar + EV combination affect CO2 emissions?
The solar + EV combination dramatically reduces household carbon emissions. Solar panels eliminate CO2 from grid electricity consumption, while the EV eliminates CO2 from gasoline. At the US grid average of 0.86 lbs CO2/kWh, a solar system that offsets 12,000 kWh per year prevents approximately 5.2 tons of CO2. Adding an EV that replaces a 30 MPG gas car driving 15,000 miles prevents another 2.2 tons per year. Total annual CO2 reduction: 7 to 10 tons, equivalent to planting 300 to 450 trees annually.
Data Sources
Data current as of February 2026. Rates and incentives are subject to change.