Introduction
Electricity is a very good energy carrier which can be converted to any other form of energy and hence the demand is increasing in a higher rate (Ramachandra, 2011a, P: 176). Generation of electricity in India is mainly dependent on fossil fuels (fossil fuels: 78%, Hydro: 22%) in which coal is the predominant source (54%) (Planning Commission, Government of India, 2011, P: 4). Dependency on fossil based energy sources is resulting in fast depletion of non-renewable energy sources, apart from the problem of pollution, GHG emission, land transformation, deforestation, etc. The utilization of land for constructing the power plants, transmission lines, substations and distributing stations is an important ecological issue and also construction of these conventional structures is a tedious process, which disturbs the region’s ecology, hydrology and biodiversity. This has necessitated an exploration for sustainable sources of electricity generation which are renewable, clean and cost effective (Environmental Health and Engineering, Inc., 2011, P: 10, TERI Energy Data Directory & Yearbook, TERI Press, New Delhi, 2011). Renewable sources currently contribute only 10% to the nation’s power basket where coal is the dominant source (56.81%). India ranks fifth in the world with 15,691.4 MW grid-connected and 367.9 MW off-grid renewable energy based power capacity. Solar energy is the promising renewable source of energy which is widely available in the country. India receives an annual average insolation more than 5 kWh/m2/day and has over 300 clear sunny days in a year (Polo et al., 2010, P: 2395). India receives good solar radiations and yet utilization of solar energy is limited to 1% due to technological and economic barriers (World Institute of Sustainable Energy, Pune, 2011, P: 57). In this scenario, technologies like solar PV, rooftop solar, solar thermal systems are indeed helpful since these are decentralized, require no waste disposal area and consume very less water (Mitavachan and Srinivasan, 2012, P: 163). India receives abundant solar energy above 5 kWh/m2/day over 58% of its land area. Efficient solar conversion technologies have the capacity to augment the nation’s regional lighting, heating and motive electricity requirements. This can potentially avoid extension of electricity grid to remote places and hence minimise the need for further fossil fuel based centralised capacity addition. Promisingly, solar conversion technologies are being promoted for off-grid electricity generation through congenial policies in India (Ministry of New and Renewable Energy, GoI, 2011, P: 18).
Solar energy has a wide range of applications by converting it into thermal energy and electric energy. Parabolic trough system, central receiver system or parabolic dish system for solar-thermal energy conversion is used (Handbook of solar radiation, Allied Publishers, New Delhi, 1981) and photovoltaic cell (PV cell) is used for solar to electric energy conversion. Solar PV cell converts solar radiation into direct current (DC) electric power using photovoltaic effect (Ordonez et al., 2010, P: 2124). The domestic electricity demand in India can be met by installing solar PV modules in an outdoor area or using rooftop PV modules. Rooftop PV system generates direct current (DC) electrical power using photovoltaic effect. This power can be stored in a battery or used as per the requirement. It uses a part of roof area (depending upon the PV module size and output) for installing PV modules which acts as an energy source. The generated electricity is stored in batteries, used directly or it fed to the grid using inverter circuit (Ramachandra and Subramanian, 1997a, P: 946). The National Solar Mission (NSM) launched in 2010, targets 200 MW off-grid solar based photovoltaic (PV) capacity by the end of its first phase in 2013. Ministry of New and Renewable Energy (MNRE), Govt. of India (GoI), has already achieved more than 38 MW by 2011 [http://www.mnre.gov.in/schemes/offgrid/solar-pv/]. In this study potential assessment is carried out for Uttara Kannada district considering the seasonal variations in the district. Digitization of rooftop area is done to estimate the roof area required to meet the domestic demand of the household using solar PV modules.
- 1.1 Need of solar potential assessment in Uttara Kannada
Stratified random sampling of household through the structured questionnaire has been carried out to assess the domestic energy requirement. Domestic monthly electricity consumption in Uttara Kannada district ranges from 50 to 100 kWh (per capita consumption is 15 to 20 kWh). Electrical energy utilization for domestic purpose (lighting, heating, etc.) tops the consumption followed by irrigation. Few small scale and medium scale industries are present in Taluk places (towns) which have the electricity consumption of 150-200 kWh per month (or lesser than 500 kWh/month) (Alam Manzoor, Sathaye Jayant and Barnes Doug, 1998, P: 2). However the district is completely dependent on grid connected electricity supply which is not reliable and does not reach remote localities. Decentralized power supply system can meet the domestic and irrigation demand of the villages and also helpful in electrifying the remote consumers.Solar PV is a promising technology which can generate sufficient electricity to meet the household and irrigation demand (Ramachandra and Krishnadas Gautham, 2011a, P: 85). Large scale deployment of solar based technologies entails solar potential assessment considering seasonal variability of solar radiation.
Abundant solar energy (5.42 kWh/m2/day) available in the region helps to meet the lighting and heating energy requirements (domestic consumption) through decentralized solutions such as rooftop solar PV systems. It directly converts solar energy into electrical energy using photoelectric effect which can feed the lighting and heating appliances of the household. Study of season wise variations in solar radiation is helpful in allocating the PV modules and forecasting the electricity generation.