In the summer, make sure it’s not very hot when your outside. (not above 80F). Make sure he has frozen bottles, wet veggies, & Ice water. I have a portable fan I lugg outdoors for my bun.I set it on low!  And they don’t need much light. I hear they have superb vision…

Rabbits don’t need direct sunlight, if that is what you are asking. I have never read anything that said they have problems like we would without vitamin D, or anything else. In fact, it really is best to keep them out of direct sunlight at all times. If they are in direct sunlight, it is VERY important they have a shaded area in order to move out from the sun. I kind of view rabbits like I do my tarantula. Everyone says that tarantulas hate light, but my girl loves to sunbathe. She loves to come and sit in the light, the brighter the better. But I also always make sure she can go into the dark, and that the light doesn’t raise the temperature of her enclosure to dangerous levels.
Also remember that rabbits are most active in the early morning and late evening, when the sun is literally the least bright. While some of ours might be odd (like my tarantula), most are going to prefer to avoid a lot of sun.