I’ve heard a lot of myths about how sunlight is a good way to clear acne. While sunlight used in moderate dosages can help both fight 
acne and reduce the appearance of acne and scars, it isn’t a catch all method and it can definitely back fire on you if you’re not careful. Our skin when it comes in contact with sunlight produces vitamin D. Vitamin D is not only known to help the skin, but also helps promote healthy hair growth, bone health and lately has been associated with helping with the flu.
If you plan on using the sun to help clear your acne, please keep in mind a couple important things:
Limit direct sun intake to 15-20 minutes: Spending too much time unprotected in the sun can lead to a whole host of problems a lot worse than acne. You’re not going to burn it off or anything like that, so limit your direct intake to 15-20 minutes. Much longer and you WILL make your acne worse due to sunburns and damage to your skin.
Sunscreen will not make your acne worse: While the oily part of the sunscreen CAN possibly irritate acne a bit, its not nearly as bad as being in the sun for long amounts of time without any sunscreen. The most important part is to make sure that you thoroughly wash your face after you come inside and get the oil when you’re done being outside.
Harsh acne products + sunlight = BAD news: Make sure to read the warnings on any acne treatments that you may be 
undergoing as some of them greatly increase your sensitivity to sunlight. In this case, its best not to use the sun to help lighten up any of your acne as you’re probably only going to make it worse. There are some pills and prescription patches that are especially known to increase suspectabilty to sunlight so make sure you follow all instructions!
When it comes down to it, getting a bit of sun will help your fight against acne, but its not a catch all solution. Getting outside once in a while, combined with a healthy diet, good hygiene, and a good acne regiment are all important parts of clearing up acne.