You can open PPF Account in your nearest SBI branch or sum nationalised bank like PNB or Post office. PPF has a maturity period for 15 years. Minimum amount to open PPF account is 500. In a year the maximum amount that you can deposit in PPF is 70000 (to get tax rebate) i.e they consider it as a higher limit. If you deposit more than 70000 also no problem. They will not give interest for the amount exceeded Rs. 70000. The amount you invest is compounded annually.

Hope this will help.