I doubt such a concept can work. Solar isn't strong enough on such a small area to power an AC
My guess is that it doesn't make sense for the car makers, financially.
For a gas powered car - it would need enough panels to generate sufficient power, but it will likely also need a battery to store excess power to help power the AC once the car gets too hot. To run the AC full time would likely be too much power, and there isn't always direct sun to power the solar.
For an EV or hybrid - they have already have a battery storing power, and the AC can run off of it. Tesla has this feature already. They can add solar but it's expensive without enough benefit. On the other hand, EV users don't want waste battery and will disable the feature unless they have very easy access to charging daily. Tesla can disable the feature when the battery is at a certain level, but then again you want this running whenever possible. Perhaps an option to run it only in morning hours (when the risk of "forgetting to drop off at daycare" is highest) can conserve battery and promote usage.
