Left side of chest is bigger than the right side. Can it be solved by exercise on the small side without surgery?

Asymmetry is common in male breasts.  There is insufficient information in your question to guide therapy.  I suggest submitting photos or scheduling an appointment with a plastic surgeon who performs a lot of gynecomastia surgeries.

Having some asymmetry is normal. If there is a noticeable difference that bothers you, you should follow up with a local plastic surgeon for a formal evaluation as treatment options will depend on the exam. 

Of course, only an in-person consultation can determine the underlying cause of the asymmetry and the possible treatments. Liposuction might be an option if the asymmetry is caused by unwanted fat, while excision-based surgery is required if the problem stems from excess breast tissue.  Ocasionally, these two procedures are combined to achieve the most desired results.Good luck and best wishes.