There are rooms(known as Saray) available in the temple to stay overnight. The cost of those rooms are very minimal. Its around Rs.150 per room. They provide blankets and mattress.
There is one camping site just near the lake. And few more camping sites are there at a distance of around 2km from the lake.
As it was evening time we decided to stay overnight in a camp rather than going back to Kullu. We stayed at Krishna Camps. It is situated at a distance of about 2km from the lake. They have around 15-20 camps. They charged us 800 per person including dinner, bonfire and breakfast next morning. The place where camps are located was very quiet and peaceful. They serve vegetable, chapati, dal and rice in dinner. The taste was good.
3 more groups stayed at that campsite. We had a good time talking with other groups and enjoyed our dinner with bonfire.