How much is the voltage of electric car's batteries? I was thinking about a DIY electric van (Mercedes Sprinter) with 3x200 watts solar panels on the roof. I'm not sure but let's say the EV batteries are 460 volts and solar panels are are there any inverters or battery charges that can charge 460 volts battery with 18-20 volts?
What really matters is the energy capacity of the batteries measured in kWh. The base Nissan Leaf has a 30 kWh battery.
With 3 x 200 W solar panels in optimum orientation and illumination would generate 0.6 kW. With 100% output and 100% inverter efficiency (both of which are impossible) you would charge the battery in 30 / 0.6 = 50 hours of continuous sunlight. Of course, since the Earth rotates this will take at least 100 hours.
\$\begingroup\$ I recently spoke with a power engineer for PGE (local power company) who has owned two Nissan Leaf cars in succession. He keeps detailed records, of course. He told me he gets an average of 4.1 miles/kWh in his most recent Leaf. (Almost exactly the average I'm getting with the 2018 Toyota Prius Plug-In Hybrid I own.) Assuming the equivalent of 600 watts at the equator at noon and 100% efficiency charging could both be sustained continuously, this translates into moving less than 2.5 miles per hour. (Earth's rotation on daily insolation expectation may differ from the equator, of course.) \$\endgroup\$– jonkApr 13, 2019 at 2:13