Solar Panels for EVs: What to Know
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- May 15
- 4 min read
Solar Panels for Electric Vehicles: What California Homeowners Need to Know
By Francie Finn | May 14, 2024
With the rise of electric vehicles (EVs) and a growing interest in sustainable living, the connection between solar power and EV charging is becoming increasingly important for California homeowners. Charging your EV with clean solar energy offers long-term environmental and financial benefits, along with increased energy independence.
Whether you're already driving an EV or planning to purchase one, this guide will help you understand how solar panels can power your vehicle more affordably and sustainably — especially in a state like California with high utility rates.
How Many Solar Panels Are Needed to Charge an EV?
The number of solar panels required to charge an EV depends on factors such as:
How many miles you drive per day
Your vehicle's efficiency (miles per kilowatt-hour)
The wattage and efficiency of your solar panels
On average, most homeowners will need 5 to 12 solar panels to support vehicle charging — assuming you’re not charging the battery from empty every day.
Daily Driving and Energy Use
To estimate your needs, consider how far you drive daily and how efficiently your EV converts electricity into mileage. For example, if your EV travels 4 miles per kWh and you drive 60 miles per day, you’ll need about 15 kWh of electricity daily to charge your vehicle.
With a 5 kW solar system, that amount of energy could be generated in just over 3 hours of direct sunlight. A 10 kW system would do the same in less than 2 hours. Most solar panels today range from 400W to 550W, meaning a 10 kW system would consist of approximately 25 panels at 400W each.
What Impacts Solar System Size for EV Charging?
Several factors determine how many panels you’ll need:
Vehicle Efficiency: The more efficient the EV, the less energy required per mile.
Panel Performance: Orientation, shading, tilt, and weather affect output.
Sunlight Availability: Homes in sunnier areas will need fewer panels.
Charging Patterns: Charging mostly at night may require a battery to store solar energy.
Charging Costs: Grid vs. Solar
Charging from the Grid
In California, with residential electricity averaging $0.32 per kWh, charging an EV at home can become expensive. For example:
An EV with a 75 kWh battery would cost $24 to charge fully.
If you drive 14,000 miles per year and your car uses 30 kWh per 100 miles, that’s 4,200 kWh/year, costing about $1,344 annually from the grid.
Charging with Solar
Installing a solar system locks in your energy rate for 25+ years and avoids rising utility costs. After your system pays for itself, typically in 6–10 years, EV charging becomes essentially free — aside from minimal maintenance.
To calculate long-term cost, divide your solar system cost by the total energy it will produce (in kWh) over its lifetime. The result is typically far lower than paying your utility provider.
Do You Need a Battery?
Green Line Construction recommends a home battery for EV owners in California. Here’s why:
Most people charge their EVs in the evening, when solar production drops to zero.
Without a battery, you'll draw power from the grid — often at peak Time-of-Use (TOU) rates, which are significantly higher.
A battery stores excess solar generated during the day for evening use, making charging more affordable and reliable.
Homeowners serviced by PG&E, SCE, or SDG&E will especially benefit from battery storage under California’s NEM 3.0 rules.
How Much Electricity Does an EV Need?
EV batteries are measured in kilowatt-hours (kWh), just like your home’s electricity usage. Battery capacity and energy consumption vary by model, but here's a general idea:
EV manufacturers recommend maintaining your battery between 20% and 80% capacity to extend its lifespan. You won’t need to charge fully every day.
Green Line Construction designs solar systems customized to your home's energy use and driving patterns. Our team helps you plan ahead and right-size your system for current and future needs.
Already Have Solar? Do You Need More Panels?
If you already have solar and plan to buy an EV, consider this:
If your system already generates surplus energy, you may be covered.
If not, adding 6–11 additional panels (depending on your EV) may be necessary.
A battery can further reduce reliance on the grid for nighttime charging.
We’ll help evaluate your system's output vs. your total household and EV energy needs to see if expansion is required.
Get Started with a Green Line Proposal
Ready to see how solar can support your EV plans?
Schedule a free consultation with a Green Line advisor.
Email us your latest utility bill and mention that you're considering an EV.
We’ll provide a custom solar quote that includes:
System size and layout
Expected energy production
Estimated savings
Optional battery and EV charger packages
Financing options
Let Green Line Construction help you power your vehicle and home with clean energy affordably and efficiently.
Author’s Note & Content Protection
Written by Francie Finn on behalf of Green Line Construction
This article reflects my professional insights and research on solar energy and electric vehicles, with a specific focus on practical benefits for California homeowners. The content is intended to educate and guide readers exploring energy-efficient home and vehicle solutions.
All materials are the intellectual property of Green Line Construction and are protected under applicable copyright laws. T
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© 2025 Francie Finn & Green Line Construction. All rights reserved.
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