As mentioned before, the surface area and a large number of panels are key to an efficient solar energy system. On an electric vehicle, even the largest ones, there is not enough surface area to meet the demands of the impressive battery, which is exactly why Tesla has shied away from using solar panels to charge their vehicles in the past.  With the Tesla Model 3, you would need somewhere in the neighborhood of 50 kilowatts to fully charge the battery. To generate that much power, you would need around 200 panels and a whopping 4,000 square feet of surface area with excellent solar exposure. You would also need an inverter. Doing this would triple the weight of the vehicle. Inverters usually weigh 40 to 60 pounds. 4,000 square feet of solar panels would weigh over 8,000 pounds The Tesla Model 3 weighs 3,500 to 4,000 pounds Enough mounting brackets and racks could weigh up to 200 pounds  Inverters usually weigh 40 to 60 pounds. 4,000 square feet of solar panels would weigh over 8,000 pounds The Tesla Model 3 weighs 3,500 to 4,000 pounds Enough mounting brackets and racks could weigh up to 200 pounds  Tripling the weight of the vehicle would present many new problems. If you were able to make a complicated mounting apparatus to house all of those solar panels, cables, and the inverter without over encumbering the electric vehicle—a task that would be difficult in and of itself—you will totally ruin the efficiency and destroy the machine. There will be more drag on the vehicle from the un-aerodynamic monstrosity surrounding the car, and the extra weight is not going to do you any favors either. If not evident at first sight, the impracticality would soon become evident when you struggled to find a parking spot the size of a very large home. You simply can not get away with it.