Can A Portable Solar Charger Be Used for An Electric Car

The quest to save our planet before it turns out to be a smothering ball of hot lava is still ongoing. More and more countries are trying to lessen the over-dependency of its economy on gas, which destroys our little green planet. One area everyone is focused on is automobiles.

Electric cars do not use fossil fuel, they work on battery power, which can be charged either at home or the general charging station, just like a gas station.

Keep in mind that the cost of operating a gas-powered car in the US is twice that of an electric car.

But what if we could drop this cost farther down a notch? What if we were to go all green and use solar power as an alternative energy source? This will appeal to all environmentalists, I am sure.

The question on everybody’s mind is can a portable solar charger be used to charge an electric car? A portable charger can be used to charge an electric car but it is going to be very inefficient due to solar energy production inefficiency and a very slow charging speed.

Can we charge electric cars with solar?

Having an electric car that is solar powered seems like an excellent step to achieve a green sustainable planet, if that matters to you, you should know that more and more electric cars continue to dominate the market and steal the market share away from their counterpart ( internal combustion engine).

Right now, the electric car world is witnessing an increase in demand for electrical cars and research technology geared towards the efficient charging of lithium-ion batteries.  Some electric car enthusiasts are looking for a seamless way to integrate the fast charging process of lithium-ion batteries with portable solar chargers.

At the current state of technology, this seems inefficient and a mirage because the numbers do not add up.

CEO of Tesla is all for Solar Power

We are now living in a world that is increasingly concerned about the burning of fossil fuel, which the CEO of Tesla and Space X, Elon musk called it the dumbest experiment in history.

Well if you look at it, we are going to run out of oil soon, we should start reducing our dependency on it and look for alternative renewable energy, such as solar energy for electric car charging.

Solar panels provide a source of electricity generated from the sun, which is about 150 million miles away.

Why are we not using solar power to charge our electric cars?

Western governments are still selling large quantities of oil.  The US government, for instance, has an 11-year reserve of oil.  This amount of oil can generate huge revenues which may be causing the US decision-makers to delay the increase in the use of solar energy to charge electric cars or to provide energy to the general public.

Furthermore, apart from the politically motivated reason slowing down the inevitable switch from oil to solar, there is also a big technical issue with solar. Solar energy generation is weather dependent.  Also, the conversion to electricity could be more inefficient.

Scientists around the world and tech companies are still trying to develop better solar panels year in year out.  Yet the most efficient portable solar panels are only 23% efficient.  This number is far too low to have any real effect on the charging of an electric car using solar panels, but let us find out how much solar energy an electric car needs.

How much energy is produced by a portable solar panel and is it Enough for an EV?

We have seen that some factors determine how much power we get from a portable solar panel.  Some of these factors can be manipulated such as the size of the panel; number and angle position of the panel.

However, there are uncontrollable factors such as the hours of daylight received which depends on the weather and the current season.  Determining the amount of power generated by the portable solar panel also largely depends on the type of solar panel and its rating.

In the solar industry today, the two predominant types of portable solar panels are monocrystalline which consists of silicon grid cells but far more efficient than polycrystalline, which is the second type of solar panel.

The sun generates an enormous amount of solar power, but only about 1000 watts per square meter reaches the earth’s surface under ideal condition or “peak sun”.

Only about  15-20 % is converted by a typical 250 watts monocrystalline portable solar panel.  This means that the solar panel will only be able to produce 150-200 Watts in good outdoor sunlight.

Let us calculate, we get approximate four hours of sunlight every day, on a very good day we can get 800 watts of energy, you can also calculate how much power your solar panel generates when you click on this link

But is 800 watts of solar power enough to power your electric car for a whole day? Let us find out.

How much energy does an electrical car need?

With the high rise of electric cars on the roads today, there is still a limited number of charging stations for electric cars,  the number of electric cars sold each year far exceeds the number of public charging stations available.  The ratio, according to a survey report on evadoption is 28:2.

Now we need to understand just how much electricity we need from our portable solar charger, if you underestimate this you will end up adding extra cost because the initial cost of setting up a solar system of any sort is always high.

It is always best to get this part right, the amount of power you will require from your portable solar panel will largely depend on the size of your electric car battery, the battery capacity inside an electric car is measured in kWh (kilowatt-hour).

Most of the time, electric car batteries come in the range of  20kwh minimum to as high as 100kwh, for example, the Nissan Leaf has a battery capacity of 40kwh, while the tesla model S  has a battery capacity of 100KWH.

If you are a homeowner, consider installing a portable solar system in your house to charge your electric car, and possibly reduce the cost of your utility bill.

If you are living in the United States this is advisable because you can earn investment tax credit when you purchase a solar system. This is equal to a 30% off of the price of the solar system, and you also get state tax credit where they deduct a part of the cost of your solar panel from your state tax.

Before we go into much details of how many portable solar panels is required to charge an electric car fully, we need to understand the mechanism of the solar-powered system

The portable solar panels do not provide electricity in a way that the appliances we have at home can use, why? Is because it outputs direct current (DC) while most of our home appliances are powered by alternating current (AC) unless you want to store electrical energy in a battery, then we use DC power but most of the times AC is in use.

Think of it this way, when you are leaving one country, let us say Europe, to go to another country like the United States, you will need dollars.  You have to exchange euros to dollars at an exchange office, let us call that “exchange office” our inverter,

An inverter is simply an electronic device that changes direct current to alternating current.  Before your generated solar electricity can be used to charge the battery in your electric car, it must be converted to alternating current.

But this will mean a consumer has to buy two separate systems, the portable solar panel, and an inverter.  Another option is to go for microinverters, which is simply a plug and use device, found in most portable solar panels.  This solar panel has a unit that converts the DC to AC built-in.

This is a far more efficient way to convert to alternating current and does not take up much space.

How many Solar panels do we need For An EV (rooftop type)

Since the typical truly portable solar panel is not powerful enough to charge an EV (could take days).  We will assume that you will be adding them to your carport or to your roof so that more electricity will be generated. Nevertheless, getting a good inverter is necessary, to convert from DC to AC.

After getting a good inverter, either the typical inverter which is referred to as the string inverter or the microinverter, you need to determine how many solar panels you will require if you are going to install it at home.

For a 12 hour change on a Chevy Volt, you need to produce about 1500 w. Just calculate how many watts your typical panel will produce and divide that number by 1500 to determine the number of panels required. Make sure that the mounting surface of your roof is wide enough if not,  you have to build a standalone solar charging station at home.

If you plan on owning more than one electrical car or adding more rooms at home, as pointed out previously, the number of panels required will largely depend on the size of the electric car battery.

Let us take a Nissan leaf for example. It has a battery capacity of 40 kWh, which is equivalent to 40,000 watts hours.

Note that, your electric car battery capacity might be different from this, the Nissan leaf I am using for this example is the 2017 model, so other models might have higher or lower battery capacity.

You can also get your electric car battery capacity at your car manufacturer’s website since you cannot just pop the hood and check the battery details as you can in a typical gas-powered car.

To get the exact number of how many solar panels required, let us take a look at how much power is output by a single solar panel.  Although this quantity is not a constant value and it varies due to factors which we have discussed above, you can still get a good affordable portable solar panel.

A typical 250 watts solar panel can generate 30 to 35 kWh of AC power in a single month, this number is derived from the assumption that on a normal sunny day we get a minimum of four hours of sunlight, i.e 1000 watts in a day or 1Kwh.

Summing it up to 30Kwh in a month though some months experience more hours of sunshine than others.  But let us take the minimum value of 30Kwh.

Since a single portable solar panel at its best can provide 1 kWh every day, this means you will need approximately 40 to 45 panel to fully charge the battery of the Nissan leaf assuming you start charging with a fully depleted battery,  45 panels will work best since some power will be lost due to heat.

However, the average road driver is said to only drives 30 miles per day, going by the charge mileage of the Nissan leaf, this roughly gives us 8 Kwh a day, which means 8 to 12  portable solar panels will be required.

But this number is only realistic if the solar panel is solely for charging the electric car and not for use at home.  On days when the weather is cloudy, it going to be difficult to even top up the charge on your electric car.

Portable solar panels on the roof of your electric car

Most people will be wondering why don’t we just put a portable solar panel over the roof of our electric car and charge the battery, to some people electric cars and solar is a match made in heaven since both of them have something to do with electricity.

Well, you might be right, but the physics hasn’t gotten to that extent yet to support it.

An electric car has very little surface area to gather the required solar power required to even top up a significant amount of charge.

Some gurus out there will show you that it works on paper, but in real life, it is not efficient enough to be feasible.

Although some electric automakers are putting portable solar panels embedded into the roof of the car, this can only power the car AC or starter motor of the electric car.  These portable solar panels do not provide enough juice to power the whole electric car


Although portable solar panels on the rooftop of an electric car and the roof of our homes is not an efficient way of charging an electric car, because of the inefficiency of solar technology. Maybe in the future, the technology will improve and there will be portable solar panels on the roof of an electric car that can charge the battery fully.

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