When are you *truly* green? The first time when you **charge a Tesla with solar panels**. It’s a phenomenal concept. We’ll explore if you can actually use solar panels to charge a Tesla *every day*. If possible, we will also calculate how many solar panels do you need to charge a Tesla.

Needless to say, using solar panels to charge a Tesla is as green as you can be. To calculate the viability of charging a Tesla with solar panels, we need to proceed in the following way:

- Check Tesla’s
**battery size**. We’re dealing with the**smallest 50 kWh battery**for Tesla Model 3 with 220 miles (350 km) range and going up to the**biggest 100 kWh battery**for Tesla Model S with 402 miles (647 km). These are all Lithium-ion (Li-ion) batteries. - Calculate
**what size solar system**we need to power Tesla’s battery in a day. Is it a 5kW, 10kW, or 15kW system? We’ll use the solar panel output formula to answer that. - Based on solar system size, determine
**how many solar panels**we need to charge a Tesla.

*Sounds rather easy, right?*

Alright, we’re going to use the basic solar panel output equation:

**Solar Output (kWh/Day) = Power Rating × Peak Sun Hours × 0.75**

We know what the solar output should be; anywhere between 50 kWh to 100 kWh. This just depends on which Tesla you have. Obviously, charging the Model 3’s 50 kWh battery will require fewer solar panels than charging Model S’s 100 kWh battery.

On average, you would need anywhere from **44 to 89 solar panels** with 300W rated power to charge a Tesla every day. You would need 1/2 of that if you were to charge it every 2 days, 1/3 of this if you would charge it every 3 days, and so on.

We will learn how to calculate how many solar panels you need to charge any Tesla car. We will go through the calculations together. For easier calculations, we have designed a **Tesla Charging Solar Calculator** (you just input Tesla’s battery size and peak sun hours, and get the number of 300W solar panels). Here’s how the calculator looks like *(you can find it and use it further on)*:

What’s more, we have used this calculator to generate a table with summarized data about how many solar panels you need to charge anything from Tesla Model 3 to Tesla Model S within a day.

Let’s start with figuring out what size solar system you need:

*Note:* Do keep in mind these are theoretical calculations that use certain averages and all-things-equal presumptions.

## How Big Solar System Do I Need To Charge A Tesla?

Essentially, big enough to produce 50 kWh, 60 kWh, 75 kWh, or 100 kWh, depending on your Tesla model.

To figure out the size of the solar system that is required to charge a Tesla every day, we need to use the upper equation. Specifically, we need to express ‘Power Rating’; this is the size of the system. Here’s how we do that:

**Power Rating = Solar Output (kWh/Day) / (Peak Sun Hours × 0.75)**

The 0.75 factor you see there is there to account for 25% energy loss any solar system suffers from (inverter loss, temperature loss, DC and AC cable loss, and so on).

The only variable that we need to determine is the **‘Peak Sun Hours’**. This is a measure of how much sunlight you get. In the US and Europe, for example, we get, on average, anywhere from 4 peak sun hours to 6 peak sun hours per day. Basically, in sunny California, you get 6 hours, and in cloudy New York, you get 4 hours.

Now we will calculate the system size for the smallest 50 kWh Model 3 battery and the biggest 100 kWh Model S battery:

### Solar System Size For Charging Model 3’s 50 kWh Battery

For Model 3, we know that we have to produce 50 kWh with solar panels in a day. This is basically it. There are other details as well we won’t factor in in our calculations, and you can read more about Tesla car batteries and their capacities on Tesla.com.

We will have two cases. In the first, we will presume that you have only **4 peak sun hours** worth of sunlight. New York, that’s you, for example. In the second, we will presume you live in sunny California and you enjoy **6 peak sun hours** worth of sunlight per day. Obviously, you will need a bigger solar system to charge a Tesla in New York than in California.

#### 1st Case: 4 Peak Sun Hours

We simply plug the numbers into the equation. We know that ‘Solar Output’ should be 50 kWh/day and that the ‘Peak Sun Hours’ is 4.

Here’s how we calculate the solar system size for Tesla Model 3 in colder climates:

Power Rating = **50 kWh/Day** / (**4 h** × 0.75) = **16.67 kW Solar System**

So, if we want to charge a Model 3 every day in a less sunny climate, we would need a 16.67 kW solar system. That’s quite a big system. If we were to use 300W solar panels, we would need **56 such solar panels** to charge a Tesla Model 3 every day.

*Note:* You could charge Tesla Model 3 50 kWh battery every 2, 3, or 4 days for example. For that you would need fewer 300W solar panels; 28 panels, 19 panels, and 14 panels, respectively.

#### 2nd Case: 6 Peak Sun Hours

If you have the pleasure of living in a country or state that receives more sunlight (solar irradiance), you’re in luck. You will need a smaller than 16.67 kW solar system to charge a Tesla Model 3 every day.

How much smaller? Well, let’s calculate. Instead of 4 peak sun hours, we will use 6 peak sun hours here to account for more sunlight:

Power Rating = **50 kWh/Day** / (**6 h** × 0.75) = **11.11 kW Solar System**

11.11 kW solar system is considered an above-average in size but not ‘very’ big. With such a system, you can generate 50 kWh of electricity per day; exactly the same quantity of electricity that Tesla Model 3’s 50 kWh battery can hold.

If you were to use standard 300W solar panels, you would need **37 solar panels** to charge a Tesla Model 3 every day in a sunny state or country (think California or Spain). That’s a lot but not impossible.

Now let’s have a look at what happens if we double the Tesla’s battery capacity to 100 kWh. Enter Model S and 100 kWh battery:

### Solar System Size For Charging Model S’s 100 kWh Battery

Model S has a battery with two times as much capacity as Model 3. That naturally means you will need *twice* the size of the solar system to charge the battery. Hence you will need two times as many solar panels to charge a Tesla Model S.

If we repeat the same two case calculations – for less sunny (4 peak sun hours) and more sunny (6 peak sun hours) climates – we get this:

Power Rating (Less Sunny) = **100 kWh/Day** / (**4 h** × 0.75) = **33.33 kW Solar System**

Power Rating (More Sunny) = **100 kWh/Day** / (**6 h** × 0.75) = **22.22 kW Solar System**

That means you will need anywhere between 22.22 kW and 33.33 kW solar system to charge a Tesla Model S (depending on how much sunlight you get).

How many solar panels do you need to charge a Tesla Model S every day? Well, if you are to use the standard 3ooW solar panels, you would need anywhere **between 74 and 111 solar panels**. That’s quite a lot.

If you would like to charge Tesla Model S every 2, 3, or 4 days, you would need on average 46, 31, or 23 3ooW solar panels, respectively.

We have simplified all these calculations for you by designing a Tesla Charging Solar Calculator:

## Tesla Charging Solar Calculator

Here’s how this calculator works. You need to know what size battery your Tesla car has; it could be anywhere between 50 kWh and 100 kWh. You also need to know how many peak sun hours your get in your area.

The calculator calculates how many 300W solar panels you need to charge your Tesla in 1 day:

### Summarized Table For Charging Tesla With Solar Panels

There are small 50 kWh Tesla Model 3 and big 100 kWh Tesla Model S batteries. You might get 4, 5, or 6 peak hours a day. Based on these variables, we have calculated how many 300W solar panels you need to charge any Tesla in **1 day **if you receive an average of **5 peak hours** per day:

Tesla’s Battery Capacity (in kWh): | Number Of Solar Panels Needed (300W): |
---|---|

50 kWh (Model 3) | 44 solar panels |

60 kWh | 53 solar panels |

70 kWh | 62 solar panels |

75 kWh | 67 solar panels |

80 kWh | 71 solar panels |

90 kWh | 80 solar panels |

100 kWh (Model S) | 89 solar panels |

Hopefully, these theoretical estimates will serve as an illustration of how many solar panels are needed to charge a Tesla. If you have any questions, you can pose them in the comments below and we’ll try to help you out.

If I have a bank of deep cycle batteries attached to my solar power system, it will allow charging overnight from the stored power. How will this cut down on panel numbers?

Hi Dave, no, not really. In the calculations, we have presumed that you do have batteries that can capture the generated solar electricity, and charge your Tesla already.