Solar Panels

How Many Solar Panels to Charge a Tesla (& Is it Worth it?)

By:Michael Johns

Charging a Tesla with Solar Panels

In this article you will learn how many solar panels to charge a Tesla.

You would imagine that solar power and electric vehicles complement each other perfectly. Afterall, to fuel a car like a Tesla you must recharge the batteries. Plus solar panels continue to be popular methods to keep deep cycle batteries fully charged.

But Teslas have huge batteries to help increase the overall range, so it’s going to take plenty of energy to recharge them. So along with working out how many solar panels you’ll need, we’ll discuss whether it’s worth it and if portable solar panels can do the job.

Tesla Fuel Efficiency and Mileage 

The first thing we need to understand is how much energy a Tesla uses. Essentially, how much electricity are you going to use when driving around in your day-to-day life.

Electric vehicle (EV) fuel efficiency, range, energy usage, and mileage can be confusing to understand. This is because the terminology has been jumbled up with traditional measurements of a combustion engine car. 

EV fuel efficiency (electricity usage efficiency) is called Miles Per Gallon Equivalent (MPGe). This is essentially a number which reflects how efficiently a car uses electric energy. To give you an idea, 33.7 kWh is comparable to a gallon of fuel in terms of energy content.  So putting 33.7 kWh of electricity into a Tesla is the same as a gallon of gas in a tank.

Just like MPG, the higher the MPGe number the more energy efficient a car is. You can see the efficiency of Tesla models in the table below. As you can see an electric car can travel over 100 miles on the equivalent of a gallon!

Model 3 (2022)113-132 MPGe26 – 30 kWh/100 mi
Model S (2022)101-120 MPGe29 – 33 kWh/100 mi
Model X (2022)91-102 MPGe33-37 kWh/100 mi
Model Y (2022)111-129 MPGe28 – 30 kWh/100 mi

In the table above you will also see ‘kWh/100 miles’. This is the number we can use to work out how many solar panels we need. It shows you how much electricity a Tesla uses to travel 100 miles. 

Tesla range

On average, a Tesla uses around 30kWh to drive 100 miles. 

This is a useful number to know as you can compare it to your utility bill. Electricity is priced per kWh on your energy bill. For example, you might be paying $0.19 per kWh.

This is handy as we can use this information to work out the cost of charging a Tesla and solar panels needed to offset this amount.

Solar Panel Power and Peak Sun Hours

The next piece of information we need is the power of an individual solar panel and amount of sunlight. 

Solar panels can vary in size. On average a residential solar panel delivers 250 Watts.

Solar panels only perform at maximum efficiency during peak sunshine hours. This is the middle of the day when the sun is strongest. In most regions this is 3 – 5 hours a day, between 11am and 3pm. During peak sunlight hours, we need solar panels to do the bulk of their electricity production. Effectively it means you have around 4 hours to generate power from a solar array.

How Many Solar Panels to Charge a Tesla?

solar panels with tesla

Below we work out that it takes 12 solar panels to charge a Tesla.

Of course, the numbers used to work out how many solar panels you need to charge a Tesla vary slightly depending on car model, panel power, and peak sunlight. 

To give you an idea, we will use the average 30kWh per 100 miles, 250 Watt solar panels, and 4 peak sun hours.

We will work out how much energy is used each day and how many solar panels we need to generate that electricity.

1. Work Out Daily kWh Consumption

So let’s work out how many kWh (KiloWatt-hours) of energy we use each day. The average American drives 40 miles a day.

We know that a Tesla uses 30kWh per 100 miles. We’re only using 40 miles a day which is 40% of this energy. 40% of 30 is 12kWh.

So a Tesla uses 12kWh a day.

2. Convert to Wh

Next we will convert 12kWh into Wh (Watt-hours). 1kWh is 1000Wh so we just multiply by 1000.

12kWh x 1000 is 12,000Wh.

So a Tesla uses 12,000Wh a day.

3. Divide by Peak Sun Hours

Remember we need to do all solar electricity production during peak sun hours. Which gives your solar panels 4 hours a day to do this. We need to produce 12,000Wh in 4 hours.

And 12,000 ÷ 4 = 3000.

We need to generate 3000 Watts an hour from solar panels.

4. Divide by Individual Solar Panel Wattage

Our solar panel system needs 3000 Watts of power and an individual solar panel is 250 watts.

3000W ÷ 250W = 12 solar panels.

It takes 12 solar panels to charge a Tesla.

Net Energy Metering vs Charging a Tesla Directly from Solar Panel

An important point for you to understand is how solar panel systems work at home. It is likely you will need to rely on Net Energy Metering to charge your Tesla. 

This is where you use the main grid to store energy to use later. During peak sunlight hours you want your solar panels to produce most of your electricity. Of course, this means you’ll be producing more than you can use during this time so the excess is sent to the main grid. Your utility company will credit you for the energy supplied to the grid. This allows you to store the economic value of energy for use later. 

By using Net Energy Metering you can then happily plug your car in to charge at any time knowing you have already produced the value of that charging energy.

If you try to charge your Tesla directly from solar panels you are going to be very restricted when you can drive and at the mercy of weather conditions. For example, you won’t be able to drive it between 11am and 3pm as this is peak charging time. Plus, you won’t be able to charge a Tesla at night as solar panels don’t work without sun.

Tesla bathed in sunlight

How Long Would a Solar Panel Take to Charge a Tesla?

As we have discussed, you generally won’t be charging a Tesla directly from solar panels so you can refer to the charging times for each specific model and charging options like wall connectors and mobile adaptors. In addition, if you have to require 12 solar panels to charge a Tesla, they will be generating up to 3000 Watts of power, this would be way too much for your charger and car to handle all at once!

For example, the level 2 charger that is suggested to install at home can deliver up to 19kW of power. So you can replace 19kW each hour at maximum. 

We already know that the average person will use 12kWh a day. So usually it will take 1 to 2 hours to recharge your Tesla every day. 

Can You Charge a Tesla with Portable Solar Panels?

Technically speaking a portable solar panel can be used to charge a Tesla, but it’s not very practical. It will take you days if not weeks to actually fully charge the massive batteries. 

For example, if you use a 200 watt portable solar panel you will produce a maximum of 800Wh of energy a day. And we need to produce 12kWh a day on average, that’s 12,000Wh! It would take you 15 days to do this with a big portable solar panel.

In other words, you’ll only charge it 2 or 3 miles of range on a good day…

So don’t bother trying to charge Tesla with a portable solar panel.

How Many Solar Panels to Charge a Tesla Summary

Want to know how many solar panels are needed to charge a Tesla? The answer is 12.

You’ll need to add a substantial amount of solar power to your home to keep your EV charged up. Of course, if you have the money and space for the installation it will save you a lot of money in the long run. Once you’ve recouped your investment, you won’t be paying to fuel your car with energy.

So it’s an awesome way to generate energy for your car but it’s not for everyone.