Solving the problem of charging an electric car with solar energy

Brad Hill from Slash Gear just provided a suggestion on how to solve an extremely challenging problem.

How many solar panels are needed to "charge for free" an electric car?

Most electric car owners will consider installing a charging station at home or utilize the ability to charge from the grid indoors. Charging the car overnight to be ready for commuting every morning may be more expensive than they think.

But what if the house is powered by solar or wind energy?

In recent years, installing solar power systems has become a clean, sustainable energy source for many households. They can save a significant amount of electricity if they have enough solar panels.

The question is, how many solar panels are needed to provide enough energy to charge an electric car?

It is important to note that there are many factors to consider when using solar energy to charge an electric car. First is the capacity of the solar power system, which affects the number of solar panels needed.

Most residential solar panels have an output capacity of about 250 watts, but there are larger panels with capacities up to 400 watts. Each individual panel generates between 1.2 to 1.5 kWh of electricity per day depending on the intensity of sunlight.

The next issue is the battery capacity and electricity consumption of the electric car.

Determining the number of charges your electric car needs per month is also an important factor in deciding how many solar panels are needed for charging.

And the last factor is the number of kilometers the owner will drive the car in a month.

It's time to calculate

According to a 2022 study from the US Department of Transportation, on average, an American drives a car for a distance of 13,476 miles (21,688 km) per year.

Some basic calculations show that on average, an American will travel 1,123 miles (1,807 km) in a month and over 37 miles (59.5 km) per day.

For example, suppose I own a Tesla Model Y electric car with a range of 310 miles (498.9 km), we see that it needs to be fully charged 4 times (actually 3.62 times) per month.

Multiplying that by the 81 kWh capacity of the battery, you get a figure of 324 kWh. Dividing it by the number of days in the month, the result is 10.8 kWh.

Divide 10.8 kWh by 5 hours of sunlight in a day (a safest estimate) to conclude that the solar power system needs to generate 2.16 kWh of electricity.

Because a significant portion of energy is lost during the conversion from light energy to electricity, the solar power system will only have about 78% output - divide by 0.78 and finally need 2.77 kW.

Then you can divide that number by the power output of the solar panels (250 W should be converted to 0.25 kW and 400 W to 0.4 kW) and the result is 11 panels of 250 W or 7 panels of 400 W.

This equation can also be applied to wind power. However, it is important to note that this equation has many variables because any small changes (range of electric car, battery capacity, number of hours of sunlight in a day, etc.) can lead to completely different results.

More importantly, without a solution to store the energy obtained from the solar power system, charging can only take place during the day.

Original article by AutoPro