Update 6-1-2022: After 3 months with the rear Tesla mesh shade in or out I decided it doesn’t seem to make allot of difference. So I took it off and stored in in the well in the boot. I figure once the radiation passes through the glass it will turn to heat in the shade or the seats, so best just to have nice air flow to remove that heat, like other sedans with large glass rear windows. I’m keeping the front one in though. As I’m 186cm so sit close to the roof and so I prefer that the mesh gets warm not my head. (I can also easily put the rear one up if I carry rear seat passengers on a hot day).
Update 03-10-2021: After a couple of weeks of spring weather, I noticed when parked, on the street at home during the day, the car interior temp would rise to high 40s, even with the windows cracked open, which didn’t seem right. When I went to check, the air inside didn’t feel that hot, so I figured the heat sensors were affected by the surface heating of the full front dash and touch screen sitting in full sun. So I tried laying a windshield shade over the dash and that worked well. Sensor temp dropped to the high thirtees. So when parking in full sun, I am going to use the windscreen shade to keep inside temps lower. (A hot dash isn’t unique to Tesla, it would have happened in my old car too, I just didn’t know about it).
21-08-2021: In Sydney and regional New South Wales summer temperatures reach 45 Celsius often and some days up to 48 to 50. Tesla Shop says their optional glass roof mesh sun shades, “reduces heat transmission into the cabin by blocking two-thirds of solar thermal load”
So, because I have been travelling in 49 and 50 degree temps in the past, such as near Albury and Moree, I thought it a good idea to get the front and rear shades.
I bought the genuine ones from the Tesla shop and they fitted really easily. However, one thing to note, is that when I sat in the back seat to fit the back shade, the mesh ends up about an inch lower than the glass roof. So without the shade my head clears the roof, but with it the mesh sits on my hair. So, if you are carrying a rear passenger of my height, (6’2”) you might like to unclip the shade for that trip.