(2) Mini Hydro Plants:
Total installed capacity is less than 2 MW with individual unit capacity ranging between 100 KW to 1 MW.
(3) Micro Hydro Plants:
Those plants which are of less than 100 KW installed capacity with individual capacity ranging between a few KW to 100 KW.
In Indian conditions, small hydro can be broadly categorized into two types as small hydroelectric project sites in the hilly regions where small streams are available.
Small hydro especially in the plains where the canal falls, utilizing regulated discharges for irrigation and water supply to towns.
The total number of small hydroelectric schemes in operation at the end of 1988 was 89 with an installed capacity of more than 171 MW. The on-going small hydro schemes numbered 87 with an aggregate installed capacity of 198 MW. About 255 small hydro projects were under investigation in various parts of the country.
The north and north eastern areas of India are hilly and mountainous. These areas are sparsely populated and accessible with difficulty. Extension of grid lines from plains is very difficult and expensive.
Setting up of diesel based stations is also difficult and uneconomical because of high cost of transportation. But these areas are blessed with a number of hilly streams which can be utilized for generation of electricity through microhydel. The energy can be distributed to the surrounding villages through isolated grids.