Solar Energy is available in abundance and is sustainable & environment friendly having immense potential in meeting the energy requirements and mitigation of green house gas emissions. Government of India announced Jawaharlal Nehru National Solar Mission (JNNSM) to give fillip to generate solar energy in the country. Ministry of New and Renewable Energy (MNRE) has sanctioned in 2010, a mission mode project to National Institute of Wind Energy (NIWE), formerly Centre for Wind Energy Technology (C-WET), Chennai for setting up the world’s largest net work of solar radiation resource assessment stations all over the country to overcome the deficiencies in the availability of investor grade ground measured solar radiation data crucial for planning and implementation of solar power projects. The project is implemented by NIWE, Chennai in two phases, in the first phase, 51 SRRA stations were set up by October, 2011, in 11 States 1 Union Territory and in the second phase, 60 SRRA stations (in 28 states and 3 UTs) and 4 Advanced Measurement Stations (AMS) by June,2014. NIWE, Chennai has also established 6 SRRA stations in Maharashtra for Maharashtra Energy Development Agency (MEDA), Government of Maharashtra under consultancy mode. SRRA project envisages assessment and quantification of solar radiation, data processing, quality of data, modeling and making of solar atlas of the country, besides the collection and analysis of solar and meteorological data, crucial for planning and implementation of solar power plant.
A typical SRRA station consists of two towers of 1.5 m and 6 m tall each for measuring solar and meteorological parameters respectively. The 1.5 m tall tower houses a solar tracker equipped with Pyranometer, Pyranometer with shading disc and Pyrheliometer to measure global, diffuse and direct irradiance respectively. The 6 m tall tower houses instruments for measuring ambient temperature, relative humidity, atmospheric pressure, wind speed & direction, rain fall and a state of-the-art data acquisition system. The solar sensors are traceable to the World Radiometric Reference (WRR) and the meteorological sensors are traceable to World Meteorological Organization (WMO). Each SRRA station is totally powered by solar panels. A trigger switch is also installed at each SRRA station to track the cleaning status of the SRRA stations on a daily basis. Data is sampled every second and averaged over a minute and transmitted to the Central Receiving Station (CRS) established at NIWE through GPRS mode.
The AMS is set up for quantification of attenuation of solar radiation due to the presence of aerosols in the atmosphere and for the measurement of the reflectivity of the earth (Albedo), incoming long wave radiation and atmospheric visibility for research and developmental activities. The four AMS installed are at National Institute of Solar Energy (NISE), Gurgaon, Indian Institute of Engineering Science and Technology (IIEST) - Howrah, Pandit Deendayal Petroleum University (PDPU), Gandhi Nagar and Prathyusha Institute of Technology and Management (PITAM), Tiruvallur. GIZ, Germany is providing technical assistance to attain and sustain high quality standards on quality measurements, checks, generation of reports and Solar Atlas of India. The applied quality control on the solar radiation data is based on Baseline Surface Radiation Network (BSRN) rules by the World Meteorological Organization (WMO), elaborated by the Management and Exploitation of Solar Resource Knowledge (MESOR).
NIWE has launched the Indian Solar Radiation Atlas, with 3 km X 3 km spatial resolution, on 03.06.2015, providing details of solar resources at any location. At present annual average values of GHI, DNI and DHI are provided along with the administrative details pertaining to the 3 km X 3 km grid. 1 to 3 years quality ground measured solar data has been used for geographical adjustment and validation of the long term (1999-2014) data from Meteosat-5 and Meteosat-7.