It is tough to store chocolates during summer season. Is there any way to prevent chocolate from melting ?
Fridge or freezer are both good places to keep your chocolate so it doesn't get melty. If those aren't an option for some reason, then try finding a cool, dark place that won't get too much hotter during the day. A couple ideas:
1) A cellar. Cellars often stay 10-15 degrees cooler than the house they're attached too.
2) Cupboards - if choosing this option, pick a cupboard that has a tight fitting door, is somewhat large (so there's more air in there to stay cool) and that is close to the floor. All of these will help it stay cooler during the day.
3) Pack in an insulator - putting it in a cooler or surrounding it with styrofoam packing, for example. Alternately, you could try to find another insulating material/food already in your kitchen (maybe packing it in rice or flour might work? You might just end up with chocolate-y rice/flour).
Really, the fridge is your best bet if you have one.
For optimal chocolate storage, you shouldn't really store it in the freezer or the fridge. Chocolate is sensitive to temperature and the taste does change if it's cooled too far. Not to mention condensation usually occurs on the chocolate afterwards, and water and chocolate are generally non-mixy things.
But then again, you might not care too much about that, and I suppose it depends on what you're using the chocolate for (baking, eating, decorating, etc.) as to whether it would matter all that much.
Personally, I would suggest a microwave. It can act as an insulator of sorts. You could also use it to keep things warm too, sort of like a vacuum flask. Works for me.