Imagine coming back home to your driveway, then connecting your electric vehicle to a power source that is completely your own. You will no longer be visiting gas stations, nor will you be subjecting yourself to the ups and downs of electricity rates, just eco-friendly, quiet energy drawn from the sun. However, for those thinking about this move to energy independence, one big question pops up, and that’s How many solar panels do you actually need?
In this article, we will discuss how my solar panels to charge a car, the calculation to find the right number for your car, and factors that affect the numbers.
How Many Solar Panels To Charge a Car: The Short Answer
It would require a total of 5 to 12 solar panels to fully charge a car. This number variation is because the final number is a personal choice, and it is greatly determined by the efficiency of the car you have, the daily commute you do, and the amount of sunlight your place gets directly.
The Core Calculation: Three-Step Formula
The three-step formula is all that you need if you want to determine the number of solar panels to charge an electric car. Now, take a practical example to perform this calculation.
Step 1: Calculate the Energy Consumption of the Car
Watt-hours per mile (Wh/mi) is the unit of measurement for energy usage. This can be thought of as your car’s MPG for electricity.
The Average: In this calculation, we use 300 Wh/mi as standard, as most of the modern EVs consume between 250 to 350 Wh/mi
Average daily drive: Take 30 miles per day as your average daily drive
According to these numbers, every day, 9kWh of energy from solar panels is required to drive.
Step 2: Calculate Your Solar Panel’s Daily Output
The label on a solar panel will inform you of the maximum that it can produce when it goes through the ideal testing conditions, but in practice, the world is not that perfect. The daily power output of a solar panel totally depends on the number of hours of sunlight it gets.
Panel Wattage (The Engine): It refers to the given power of the solar panel during perfect testing conditions. You can consider it as the size of the engine. We use the 400W for the calculation as the power output range is between 400–450 W.
Peak Sun Hours (The Fuel): This is a crucial concept. It doesn’t mean total daylight hours. Instead, it condenses all the varying sunlight of a day into an equivalent number of hours at maximum, “peak” intensity. Your location is the primary dictator of this value.
Sunny States (AZ, CA, NV): 5.5 – 6.5 peak sun hours
Average Sun States (TX, CO, NC): 4.5 – 5 peak sun hours
Less Sunny States (WA, OR, NY): 3.5 – 4 peak sun hours
Step 3: Divide to Find the Number of Panels
Now, we simply divide your car’s need by one panel’s output.
Daily Energy Need / Daily Panel Output = Number of Panels needed
Now, put the numbers: 9 kWh / 2 kWh = 4.5 Panels
Then round up to five panels since a half panel cannot be used.
For an average driver having an average EV and living in an average place, it is enough to have 5 solar panels of 400W each to fully cover their daily commute.
Factors That Affect the Number
The estimation of the number of solar panels needed to charge an electric car will largely depend on these essential factors:
- The Efficiency of Your Electric Vehicle: EVs differ greatly when it comes to energy consumption.
- High Efficiency (Less Panels Required): Tesla Model 3 or Hyundai Ioniq 6, for instance, can reach efficiencies near 250 Wh/mi.
- The low efficiency of the vehicle (more solar panels needed): The bigger trucks like the Ford F-150 Lightning or Rivian R1T can be destined for an expenditure of 450-500 Wh/mi in unfavorable conditions (such as towing or aggressive driving), or even more.
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- The Daily Commute: Are you the one who drives 15 miles a day or 60? The average of 30 miles is merely a baseline. The major cause for the installation of additional panels is a long daily commute.
- Solar Panel Efficiency and Wattage: The roof area of a system consisting of high-efficiency 450W panels will generate more electricity than a system of 350W panels, which implies that you will require fewer of them.
- Your Geographic Location (Peak Sun Hours): This is a massive variable. Someone in Phoenix will generate nearly twice the solar energy from the same system as someone in Seattle, especially in the winter.
- Method of Charging:
- Grid-Tied (Suggested): The grid power is linked to the solar panel. Night-time charging of your car can be done with the credits that you earned by transferring extra solar energy to the grid. This makes the grid an efficient “battery,” which is why the panel calculation is successful.
- Off-Grid (Complex): This is impractical for the majority of houses since it needs a huge, costly battery bank to store power for recharge.
The Bigger Picture: Sizing a Solar System for Your Home and Car
- The majority of homeowners don’t make an extra small system for the electric vehicle, but rather they make a whole-home solar system larger or an existing one larger to cover their new electricity usage.
- To find out the annual kWh usage of your house, check the electricity bills for your house for the last twelve months.
- After that, include the consumption for charging the electric vehicle that you expect (for instance, 9 kWh/day * 365 days = ~3,300 kWh/year).
An experienced solar installer will calculate the kWh total for this and, together with your roof specifications and site, will design a system that covers the energy costs for your home and vehicle 100%.
In the end, the majority of the homeowners consider that the installation of 5-10 solar panels will be enough to meet their car charging requirements. The most reasonable way to go is to ask for a professional evaluation for a whole-house system, taking advantage of tax credits to reduce costs to a minimum. If you choose to do this, you can easily move to a future that is not only eco-friendly but also cheaper, and that will be entirely supported by solar energy.
