They develop a solar roof for electric cars with invisible photovoltaic cells – Technology – Hybrids and Electrical

When we talk about autonomy in an electric car, anything that extends it a little more will be welcome. Lately we are seeing the application of photovoltaic panels in cars grow, such as in the Hyundai Sonata Hybrid, as another way to get energy and then turn it into motion. Until now, adding such a roof was clearly notorious, but the Fraunhofer Institute for Solar Energy Systems has just introduced a sunroof for electric cars that not only promises great efficiency but also has virtually invisible cells So the roof can be chosen in any color and blend with the roof of the car.

According to its creators, the photovoltaic cells of the roof in question have a nominal power of approximately 210 W / m² and on sunny days can provide up to 10 kilometers of extra autonomy To an electric car. Throughout a whole year, they estimate that they can increase car autonomy by 10%; Although this data is very relative, the calculation is based on solar radiation from Freiburg in Brisgovia in a car with an energy consumption of 17 kWh / 100 km and an annual mileage of 15,000 km.

Solar energy can also be used to power the air conditioning or heating systems, two auxiliary elements that normally feed from the main battery and reduce autonomy. This new sunroof, which will be presented to the public at the next Frankfurt Motor Show, also has another interesting novelty. And it is that its developers have achieved that the roof can be manufacture in any color, with solar cells integrated invisibly in the roof.

This is possible thanks to the application of a special paint called Morpho-Color® that lets sunlight through and with which the color fan is "almost infinite". According to its creators, the loss of relative efficiency due to this coating it is only 7 percent, something that is tried to compensate thanks to the tile interconnection system with which the photovoltaic roof cells are constructed: monocrystalline silicon cells overlap each other and are electrically connected with a conductive adhesive, which minimizes the gap between cells (electrically inactive surface) and makes better use of the available space on the roof of the car.

There is also less losses due to resistance, The voltage can be higher than a conventional sunroof (which facilitates the arrival of electricity to the battery) and the car overheating is reduced. The end result is a photovoltaic roof that could well go through one more panoramic roof, thus reducing the visual impact of filling the car body panels with photovoltaic panels.