Skin peel procedures: I had light brown skin but due to sun exposure my skin turned dark brown.

Hi!  A skincare regimen that focuses on brightening and lightening the skin would also be very important in addition to the chemical peels.  There are many types of chemical peels on the market, with varying strengths and thus side effects/down time.  Discuss with your physician your goal and what you're able to tolerate for down time and hopefully they will choose the right peel for you.
Peels chosen and performed correctly rarely have any permanent negative side effects. 
Good luck,
Dr. Huo