How Many Solar Panels to Charge a Tesla?

Someone just wants to know whether they can charge anything at home, like TV, electiric bike or even car. The answer is yes. You can charge anything with a battery. At this time, someone wants to use the solar panels to charge the Tesla, you definitely can do it.

Before the first step, you need to size the solar power systems, now you will find that the load drives everything. At this time, you need to know how much energy the 450w solar panel need to generate to replace the energy discharged from the solar battery.

At most times, 10 solar panels rated at 300 watts each will be required to charge a Tesla electric vehicle if the daily mileage was around 30 miles, which is the average commute distance in the USA. The energy needed is about 6kWh, representing about 6.5% of A Tesla S 85kWh battery.

 Tesla Models With Battery Sizes And Range

Model	Battery Size (kWh)	Range (miles)	Battery Weight (pounds)	Number of cells
S	85	402	1200	7104
3	50/82	220/353	1054	4416
X	100	348	1200
Roadster	100	244	1836
Cybertruck	120	460
Y	80	244

How Long Would It Take to Charge a Tesla with Solar Panels?

You had better use an inverter to power the normal Tesla charger. In this case the charging time would be the same as the regular charger time, if the solar panel array is correctly sized.

If you choose to use a home charger, a Tesla would be charged in a day.

There are still two needed factors to consider when sizing solar panels is the size of the individual panels and the irradiance in your geographic location.

Of course, you need to know that there are several factors affecting solar system output, irradiance (the sun’s energy) in kWh/m2/day is by far the most important.

It’s also called peak-sun-hours and is used by solar installers to estimate solar panel array size.

Irradiance is found by consulting historic database values such as this is found on the site GlobalAtlasInfo – see the image below:

The image shows the irradiance for Houston, Tx as 1552 peak-sun-hours per year, which equals 4.25 peak-sun-hours per day. I’ll use this value for our calculation.

Keep in mind: Don’t imagine that you can connect solar panels directly to the Tesla battery to charge them up. It seems to make sense, but this isn’t how it works.

The safest way is to use an inverter and plug in the regular charger. There  will be losses associated with the inverter, but these will be minimal if it is sized properly i.e. about the same rating as the solar panel array in watts.

Solar power required = 11kWh (for 60 miles commute)/4.25 peak-sun-hours = 2588 watts

Number of solar panels required = 2588/300 = 8.62 (9) solar panels 300 watts each

How Many Solar Panels Does It Take to Charge a Tesla Overnight?

Solar panels can’t store electricity so a battery bank will be needed to charge at night. The size of the battery energy storage system can be calculated using the value of battery discharge in kWh.

In the case of a 60 mile commute for a Tesla S, this is 11kWh

Energy required = 11kWh/charging time (say 8 hours)  = 11000/8 = 1375Ah

Number of batteries required = 1375/200 = 6.87 (7) batteries each 200Ah 

Cost of batteries approximately $3000