Why Don’t We Have Solar Powered Cars?

Most of us agree that the days of the internal combustion engine are numbered. That’s because of the harm they pose to the environment both in terms of harmful emissions as well as the associated effects of drilling for oil. 

Electric vehicles are being seen as a viable alternative to ICE ones because they do not give off harmful gases. However, the energy used to charge them is generated from power plants that still rely on fossil fuels. 

In addition to this, there is a negative environmental impact when mining lithium and other precious metals that go into an EV battery pack. Though the technologies differ between ICE and EVs, neither one is a perfect solution to our problems.

Solar cars, or vehicles fitted with solar panels were at one point heralded as the future of mobility. The reason for this is perfectly logical. Solar cells harness sunlight to create electricity, which is then used to charge the onboard batteries.

When solar cells, also known as photovoltaic cells, absorb enough photons from sunlight, they dislodge their electrons that then move towards the surface of the cell. This movement creates an imbalance of charge between the front and back portions of said cell, creating a voltage potential. This flow of electrons creates the electricity needed to charge the batteries.

Since we have an ample amount of sunlight, wouldn’t it be a good idea to cover the external surface of each EV with solar panels? That will allow us to have unlimited free energy throughout the lifespan of the car, right?

Well, the problem lies in the efficiency of solar cells. As of today, most of them offer about 20% efficiency. They are only able to convert a small amount of sunlight into actual, usable electric power. In addition to this, it must be exposed to direct sunlight on a perfect sunny day to be able to capture the maximum number of photons.

The best way to overcome the efficiency problem is to have a large array of solar panels fitted together. This is why it is used as a power generating option for houses, buildings and EV charging facilities. But vehicles have a limited surface area, which makes things more difficult.

Based on the calculations by Engineering Explained, solar cells fitted to an average sized car can generate about 12kW of usable power on a sunny day. This would take days to fully recharge most EV battery packs, especially those with higher capacity ones.

Besides this, you’ll need nothing less than perfect weather to achieve the best results, which is something that doesn’t happen every day. This will leave you at the mercy of the elements on whether you’re able to drive your solar car on a particular day.

Then there’s the problem of degradation. Solar panels can last for about 20 years; however, their efficiency deteriorates with age. This means that the power that they can generate over time decreases. On average the degradation rate on regular panels is about 0.5% each year.

These issues, when combined, make the prospect of owning a solar car less attractive. More expensive solar panels, used for specific applications, do offer efficiency in the 50% range but the costs may not be suitable for mass market vehicles. 

Until we can make solar panels far more efficient than they are today, the dream of having a solar car is a non-starter.