EXV4 model equipped with solar panel charging system designed to develop up to 500 watts of energy from the sun to recharge the main drive system 72 volt battery pack in the vehicle. This option can help extend range and lengthen battery life. Solar system is fully automatic. Also vehicle can be re-charged by its main on board charger at anytime.
Improved range varies on the amount of solar insolation in your area, efficiency of the system and driving scenario. For example a graph we use shows Boulder, CO having an average of 4.87 full sun hours in a day. The minimum watts it takes to drive the vehicle 1 mile is about 250 watts. 4.87 x 500 watts = 2435 watts produced in an a single day / 250 watts per mile = extending the range a maximum of 9.75 miles per day. In city driving scenarios watts per mile could increase to as much as 500 watts and the solar system isn't 100% efficient. These numbers are just to give you an idea of what you could see from the system. There are a lot of variables that can lower the miles gained by the system.
For improved battery life basically if you are keeping the batteries at a higher state of charge the battery can handle more cycles. The deeper the state of charge the less overall life cycles the battery will see. Think of it as bending a piece of metal until it breaks. The further you bend it the sooner it breaks. This same concept applies to a battery. It can handle only so many cycles.
See EXV4 model for full vehicle specifications.