Almost 70% of India’s population depends on agriculture either directly or indirectly. While 44% of the 140 million hectare agricultural lands depend on irrigation, the rest relies on the monsoon. Most electrical consumption in agricultural sector is used for operating pump-sets for irrigation. In 2006-07, India’s agricultural sector accounted for 22% of the total electricity consumption, up from 10% in the 1970s. There are about 21 million irrigation pump sets in India, of which about 9 million are run on diesel and the rest are grid-based. Grid electricity for agriculture in India is provided at a highly subsidized low tariffs-in most cases, flat rates are charged based on the ratings of the pump. This is largely due to logistical difficulties faced with metering and charge collection. But this practice of providing electricity to farmers at highly subsidized rates has led to increasingly high consumption patterns and widespread use of inefficient pumps across the nation. These factors, among others, have led to an invidious irrigation–energy nexus. Apart from this, limited and unreliable supply of grid electricity has led to farmers’ extensive dependence on diesel for water pumping.
On an average Eastern India receives 1600 kWh m-2 of solar radiation per year with 250 sunny days, favouring the use of solar energy for water pumping. Some past studies revealed that Solar-PV-based irrigation pump sets are competitive at today’s cost relative to diesel-based pumps based on cost per unit of electricity or work done. Economic analysis showed that small and medium pump sets of 1 HP and 2 HP capacities used to lift water from depths up to 70 and 160 m respectively are cost competitive. Therefore, the Solar PV pumping system is a viable alternative in economic and environmental terms to diesel pumps in areas where there is no or highly unreliable grid connectivity.
In spite of the aforesaid facts, the key barrier to the large-scale dissemination of solar PV water pumps is the high capital cost incurred by farmers compared to the much lower capital cost of conventional pumps. Solar PV is a competitive option in the face of diesel, its adoption being contingent on the ease of access to subsidies. Another factor to be considered is the space requirement for the installation of a solar PV pump set. For every kWp installed, a space of 10 m2 is necessary. For example, in order to install a 10 HP pump, 74.6 m2 of land would be necessary. This factor limits adoption by small-scale farmers to whom land availability is a major concern. If it is assumed that a moderate 50% of the total diesel pumps in India (of the 9 million pump sets) are replaced by solar PV, the total potential for savings in diesel fuel will be approximately 185 billion kg per year. In terms of carbon dioxide, approximately 470 billion kg could be abated annually.
Moreover, cropping intensity of eastern Indian agriculture can be increased if a stand alone irrigation system like SPV based pumping system is available at affordable cost. To achieve this, considerable R & D efforts are required to reduce the price of both SPV panel as well as the SPV pump to suit the requirement and affordability of local farmers. The Ministry of New and Renewable Energy (MNRE), Govt. of India, has a program for the deployment of various solar PV applications, including water pumping systems. Under the program, the MNRE will provide a capital subsidy of 30% of the benchmark cost and/or 5% interest-bearing loans for installation of systems with a maximum capacity of 5 kWp.