6. Results, analyses and discussion
6.1. Solar radiation in Karnataka
Karnataka receives global solar radiation in the range of 5.1–6.4 kWh/sq.m during summer, 3.5-5.3 kWh/sq.m during monsoon, and 3.8–5.9 kWh/sq.m during winter. The analysis reveals that, maximum global solar radiation is in districts such as Uttara Kannada, Dakshina Kannada etc. The study identifies that Coastal parts of Karnataka with the higher global solar radiation is ideally suited for harvesting solar energy.
Global solar radiation in Uttara Kannada during summer, monsoon and winter are 6.31, 4.16 and 5.48 kWh/sq.m respectively. Similarly, Dakshina Kannada has 6.16, 3.89 and 5.21 kWh/sq.m during summer, monsoon and winter. Where as Mandya district has minimum global solar radiation of 5.41, 3.45, 3.73 kWh/sq.m during summer, monsoon and winter. The results were implemented in GIS to obtain maps showing district wise variation of global solar radiation. Fig. 3 shows the district wise variation of global solar radiation during summer, Fig. 4 during monsoon, and Fig. 5 during winter.
6. 2. Present status in Karnataka
Though successive governments have installed 700 PV pumps, 26,000 PV domestic lighting units, 800 PV based TV and community units and 30,000 PV powered street lights, which together generate some 530 kW, a great deal needs to be done to deliver Photo Voltaic on a large scale. Table 1 gives the district wise utilization of solar lanterns, home lights, and street lights (1996–2002).
Many bulk applications of energy (like cooking and heating) need only a low-grade energy source, and hence it makes sense to make solar thermal devices available to households on a large scale. However, the installation of solar water heating devices appears to have slowed down, even though major savings can be achieved through the use of solar passive systems for heating and cooling buildings, apart from the few isolated architectural experiments, not much has been achieved in this area .
The total number of industrial and commercial systems installed in the state is around 150 in the range 1000 liters per day (35 systems), 1000 to 5000 LPD (72 systems), 10000 LPD (10 systems). Assuming that the system is used effectively for 225 days in a year the amount of equivalent electrical energy saved annually is 6 million units. In Bangalore city alone 4.2 lakh All Electric Houses (AEH) consume electricity for water heating. The amount of electrical energy that can be saved by installing solar water heaters is approximately 1.8 million units. The generation capacity required to meet their demand is 250 MW, which will cost the state Rs. 380 crore. But for installing the solar heating to All Electric Homes (AEH) in Bangalore city would cost Rs. 250 crore
The cost of domestic water heater is between Rs. 8000 and Rs. 10000. Government of India provides a subsidy of Rs. 3000 to each person who goes for it. Solar heaters save about 50 to 75 kWh of energy per month per household. By educating people about solar energy through mass media substantial saving in electric energy and fuel wood could be achieved. The reasons for low-level market penetration are high capital cost of the system, inadequate fund for disbursement of subsidy, absence of attractive financial package for buyers and lack of awareness of the technology.