Theoretically, imagine entire body of Model S/X is covered in solar panels (roof, trunk, hood). Will generated solar energy be higher or equal to vampire drain?
Figure 150 Watts per square meter, max. Measure the area available then do the math. Not rocket science. ~Larry
I think there was another discussion about putting solar panels on a Model S a month or so back. Solar panels vary output based on angle of the sun, how cloudy it is, etc. The further north (or south in the Southern Hemisphere) you go, the less efficient a panel is going to be, even in direct sunlight. On a sunny day you can probably get enough panels on a Model S to beat vampire drain, but you might not be able to in a place like Seattle in the winter.
Should be able to produce more than vampire drain - let's say you manage to squeeze a .5kW array onto the car - could generate 2.5 to 3 kW max on a sunny day in the right part of the world. Perhaps not enough to justify the inclusion, although I personally feel this kind of configuration will become commonplace on certain types of vehicles as we see PV tech improve, especially with regards to Perovskite and thin film panels. Broadly speaking a LWB panel van (VW Transporter, Renault Traffic etc) should afford 7 - 8 m2 space using the roof and bonnet, allowing for a maybe 1kW system, thus perhaps 5 to 6kW could be achieved with the same caveats. There are some issues associated with this. Obviously seasonal and locational sensitivity - this kind of thing would be great here in Brisbane during summer but not so great elsewhere. There are some technical factors too - the panels will provide a relatively low voltage which will have to be stepped up drastically to charge the high voltage pack. Not to mention you have to park your car in the sun all day - not ideal for most :tongue: A better idea for all intents and purposes is to put the same array on the roof of your house - let it power your house, charge the car and collect more sunlight (depends on the roof positioning). Plus you get to park your baby under cover too. Note: this option may require a house. House sold separately.
Not to mention the extra weight in the wrong place (high up) and the cost. Toyota charges $1500 for a panel that can barely run a ventilator fan. Also a solar panel is only good if the car is parked outside. Most folks in the South try to park under some shade whenever possible.
In a Model S, the battery management system uses about 40 watts. To keep the computer(s) and the GSM modem fired up also takes additional power. This is all handled by a relatively small 12 volt deep cycle lead acid battery. That battery often needs replacement after a year or two due to the cycling load. When the 12 volt battery is run down, the high voltage traction pack is engaged and it charges the 12 volt battery through a DC to DC converter. If there was a solar charger for the 12 volt battery, then it might be possible in many situations to cover the drain from the battery management system, reduce the impact on the cycle life of the 12 volt battery, and reduce the number of cycles that engage the high voltage battery and the losses associated with then charging the 12 volt battery from the traction pack. That alone could result eliminating about 1 kWh of traction pack losses per day. It could mean that there would be zero losses of range at an airport parking, even in a garage with less than full sun.
