Introduction

Solar power installed capacityhas increased from only 3.7 MW in 2005 to about 5248 MW in 2016. The Government of India has an ambitious policy Jawaharlal Nehru National Solar Mission, launched in 2010, of expanding solar capacity to 175 GW by 2022 through solar parks, ultra mega solar power projects, canal top solar projects, 100,000 solar pumps for farmers, and, solarisation of petrol pumps. Decentralised generation of electricity at the distribution side of the power supply network or closer to the load centre itself, can play pivotal role in meeting electricity demand in a reliable and environment friendly way.

Dispersed or decentralised generation exploits locally available energy resources and reduces the exploitation of conventional energy resources and the congestion in generating units. Decentralised generation based on renewable energy (RE) sources promotes higher penetration of RE resources into the grid. These plants have the unique advantage of operating in islanded mode (grid isolation mode), during an outage of the central grid. In such cases, grid connection can easily be restored as the grid is energised and electricity can either be transferred to the grid or drawn from the grid.

Micro grids are the building units of dispersed generation, which essentially exploits locally avail¬able RE resources. The micro grid is an emerging technology and is a smart grid with high reliability, limited greenhouse gas (GHG) emission, reduced transmission and distribution (T&D) losses. The smart grid architecture is in its infancy, and inte¬grates RE based distributed generation with the conventional system using control strategies over a two way communication link.

Indiahas one ofthe biggest power supplynetworks, with an installed capacity of more than 298 GW. Though electricity is one of the cleaner energy forms, 69 per cent of India's generation, amounting to 201 GW is from thermal power plants.

In July 2012, the Indian power sector witnessed one of the biggest blackouts; this was primarily due to peak power shortfall of 12,159 MW, amounting to 9 per cent and an 8.7 per cent energy shortage amounting to 86,905 GWh during 2012-13 (Load Generation Balance Report 2014-15).

Distributed electricity generation through RE sources can help in strengthening the power system to tide over such outages and also reduce the carbon footprint of energy generation. The associ¬ated economic benefits of decentralised generation are reduced operation and maintenance costs, increased productivity, reduction in fuel costs and increased efficiency.

Southern India currently harvests electricity from hydro and limited coal resources, from Nevyeli in Tamil Nadu. With three metropolitan cities in Bangalore, Chennai and Hyderabad, and many industrial, agriculture and commercial consumers, there is high demand for energy. The region has been facing very high energy (59,297 GWh, 19.1 per cent ) and peak power (11,669 MW, 26.1 per cent ) crisis over the years, which has, in turn, resulted in decreased power quality and load shedding, as admitted by the Central Electricity Authority (CEA) as per its Local Generating Balance Report, 2013-14.

Several studies have looked into the prospects of RE for decentralised generation (Ramach-andra & Krishnadas, 2012; Ramachandra & Shruthi, 2005), micro grid (Ramachandra, et al., 2014; Ramachandra et al., 2014) and stand-alone generation of remote area electrification (Hafez & Bhattacharya, 2012; Ibrahim,et al., 2002, Balamurugan et al., 2009). Energy potential analysis using spatial data are also carried out by researchers which gave new avenue for energy research (Kanase-Patil et al., 2009; Kumaravel & Ashok, 2012). However, most of the studies were done for a specified application in a region or for a cluster of villages. The present study analyses the solar energy potential for all of southern India. The solar energy potential of the region ranges from 5.2 to 6.0 kWh/m2/day annually. Taluk wise RE resources assessment has been carried out consid¬ering the seasonal variability of the resources and clustering high energy yielding regions.