Scarcity of electricity coupled with the increasing unreliability of monsoon rains and prevalent costly diesel pumping systems pose an economic risk to small and marginal farmers. A complex set of factors including global warming, competitive land use and lack of basic infrastructure is creating new challenges for India’s vast agrarian population. The ever increasing mismatch between demand and supply of energy, and electricity in particular, is posing challenges especially to farmers in remote areas. This coupled with the increasing unreliability of monsoon rains is forcing farmers to look at alternate fuels such as diesel for running irrigation pump sets. Currently, India uses 12 million grid based (electric) and 9 million diesel irrigation pump sets (C-STEP 2010). However, the high operational cost of diesel pump sets forces farmers to practice deficit irrigation of crops, considerably reducing their yield and income. Solar water pumping systems constitute a cost-effective alternative to irrigation pump sets that run on grid electricity or diesel. The performance of a solar water pumping system is discussed in this paper; the system consists of a photovoltaic (PV) array, a permanent magnet (PM) DC motor and a helical rotor pump. Coupling with solar wind energy is added advantage for electricity generation. Simulation and field test results are presented.
Energy is a key ingredient for the overall development of an economy. India has been endowed with abundant renewable solar energy resource. India is large country and the rate of electrification has not kept pace with the expanding population, urbanization and industrialization and has resulted in the increasing deficit between demand and supply of electricity. This has not only resulted in under electrification but also put heavy pressure on the governments to keep pace with demand for electricity. People not served by the power grid have to rely on fossil fuels like kerosene and diesel for their energy needs and also incur heavy recurring expenditure for the poor people in rural areas. Wherever the rural areas have been brought under power grid the erratic and unreliable power supply has not helped the farmers and the need for an uninterrupted power supply especially during the critical farming period has been has been a major area of concern. India receives a solar energy equivalent of 5,000 trillion kWh/year with a daily average solar energy incidence of 4-7 kWh/m2 . This is considerably more than the total energy consumption of the country. Further, most parts of the country experience 250-300 sunny days in a year, which makes solar energy a viable option in these areas. Among the solar technologies useful in agriculture are water lifting and pumping with solar photovoltaic systems. Water pumping by solar power is a concept which has won widespread interest since the early seventies. Solar energy can be utilized to operate pumps, utilizing either the thermal or light part of solar radiation. With a solar pump, energy is not available on demand, and the daily variation in solar power generation necessitates the storage of a surplus of water pumped on sunny days for use on cloudy days. In view of the fluctuating water demand of any irrigation scheme, solar energy needs to be reserved in the form of either electricity in batteries or lifted water in a storage tank. The suitability of solar power for lifting water to irrigate plants is undeniable because of the complementarity between solar irradiance and water requirements of crops. The more intensively the sun is shining the higher is the power to supply irrigation water while on the other hand on rainy days irrigation is neither possible nor needed. Small scale irrigation is one of the most potential applications of solar power. The main advantage is that solar radiation is intense when the need for irrigation is high. Further, solar power is available at the point of use, making the farmer independent of fuel supplies or electrical transmission lines. The solar pumps have the potential to revolutionize small scale irrigation in the developing countries in the near future. The technical feasibility of solar (photo voltaic) pumps have been established.The major limiting factor has been the high cost and the lack of familiarity of the technology which require concerted effort in training of technicians and large scale introduction in a region with adequate technical support. However with the incentives and initiatives undertaken by MNES/State Govt the scheme may be propagated in rural areas for small irrigation system in far flung rural areas where electrification is a costly proposition. The model scheme is to introduce solar water pumping and support irrigation schemes to provide a sustainable economic activity to farmers in non-electrified or under electrified rural areas .Various agencies and financial institutions are in place to assist in developing credit scheme targeted for non-electrified rural area.
Cost effective: The life cycle and the cost to ultimate beneficiary make the SPV systems cost effective as compared to conventional systems. IN addition the farmer is saved from the capital investment he has to make for drawing lines from the grid to his field/farms. The govt. may save huge resources which otherwise may be uneconomical to network every agriculture field under the state electricity grid.
Reliable: The SPV is more reliable, consistent and predictable power option as compared to conventional power system in rural areas.
Free fuel: Sunlight, the fuel source of SPV system is a widely available, inexhaustible, and reliable and free energy source. Hence the SPV system has no monthly fuel bills.
Low maintenance: The system operates on little servicing and no refueling, making them popular for remote rural areas, hence the operation and maintenance is very low. The suppliers provide maintenance at a very low annual maintenance contract rates.
Local generation of power: The SPV system make use of local resource-sunlight. This provides greater energy security and control of access to energy.
Easy transportation: As SPV systems are modular in nature they can easily be transported in pieces/components and are easily expandable to enhance the capacity.
Energy Conservation: Solar energy is clearly one of the most effective energy conservation programs and provides a means for decentralized PV-generated power in rural areas.
Water conservation: The SPV sets are highly economical when combined with water conservation techniques such as drip irrigation & night time distribution of (day time pumped & stored) water. The SPV system leads to optimum exploitation of scarce ground water.
Environmental friendly: The use of sunlight as a source of fuel leads to clean, eco-friendly and decentralized generation of energy which saves the fossil fuel, controls deforestation and prevents environmental pollution.