1) Current estimates are 20-30 years for the latest generation quality cells, but I very much doubt Toyota would spend that much money on the latest and greatest tech (especially as it won’t be used optimally).
2) Yes some UV gets through (about 1/3 to ¼) but others (who I will no longer let bring me down to his level) seem to think that clouds being transparent to UV will make everything OK even though the UV accounts for less than 5% of the useful energy received at sea level.
As I already said, I don’t believe this additional panel will do much to reduce the CO2 footprint (if you believe we should be doing so).
The difference between solar panels and (non-dark) paint is that paint will re-radiate mostly at 3000-6000 K, not 300K (visible wavelengths, not IR).
3) I said ‘many people’ wash their car, not “everyone”; now everyone with a panel would have to (to aid towards optimal use) – which was my point ;c)
4) Airbags, seatbelts, fog lights, headlights are all useful (some in certain circumstances), they help prevent occupants (and other road users) from dying, so on average they all add significant value even though they don’t earn money. Car tax and this additional panel aren’t useful, don’t add value but yes: they do earn money - but not for you. Leaving the car in the sun more will completely kill the argument about the benefit to aircon (hot car). Also, doing so will also accelerate the decay of the cells and paintwork. When the car is not being driven and it’s not used to charge or power something at maximum possible panel power, what’s exactly is the point of keeping it in the sun when not in use? The engine will have already topped up the battery (it has to otherwise one risks not being able to start the car). All it will do give ~1W to power the alarm and battery and convert the other 99% of the energy to IR and heat.
Damn that is a good point; for me that completely kills the utilisation and payback aspects.
5) Expensive but efficient panels, accounting for non-optimal factors, will result with insignificant payback. Inexpensive but inefficient panels, again accounting for non-optimal factors, will result with insignificant payback. Either way it doesn’t work with today’s tech. If people want to make real use of the energy they provide then they should rip them from those cars and use them more optimally, like strategically placed/angled roofs, or better yet on motorised beds, not on cars.
Now I think of it, this is where the harm is. The false notion that these things are useful has resulted with misallocation of what would otherwise have been a useful energy resource. Regardless of panel efficiency, we should wait for panels to used on all houses before we even consider mounting them to cars; the latter also being at significantly greater risk of breakages through crashing or vandalism – or even being stolen!
Couple that with the fact that you’ll never utilise full possible power anywhere near the maximum possible time (when mounted onto the car), it’s a dead duck. In fact, it's likely that the use of it on a car as increased the CO2 footprint (negative 'net energy') - how ironic!