controlling sun derived heat gain

1) have a small solar panel incorporated in the dash inside of the windshield or back window, to power a small fan to keep the interior of the vehicle from getting hot. when parked in warmer climates or when the inside temp reaches over 100'f. (the solar panel would prevent the vehicles battery from going dead over a multi-day period of non-use)..
2)another comfort feature would be, to incorporate a radiant heat barrier and a layer of insulating material between the sheet metal and head liner. reducing the heat gain when parked in the sun…
3)a solar reflective material imbedded in the vehicles glass would be a great addition..
thank you for innovative designs and producing a product with lasting value and reliability.