1. Use a one-handed backhand, its superior
2. Get a good shoulder turn, (shoulder facing the side fence)
3. Step into your shot
4. Dont open up your swing until the ball is crossing the net toward your opponent
5. Keep the head still and eyes locked on to the ball
6. Keep a relaxed hitting arm and extend fully towards your target, arm should be almost straight at contact (slight elbow bend) and completely straight during the follow through.
7. For power bend the knees and get low, then use the legs to help create power on your stroke.
I can hit a backhand about 100 mph if i really try to rip it, granted i cant do that consistently but im just telling you i know how to generate serious power with a one-hander, the above mentioned are the keys to making it solid and potentially explosive.