Harness the sun on your rooftop

Three R's - renew, recycle and reuse are buzzwords these days. The Karnataka government has been stressing on the importance of the 3R concept to curb pollution, check global warming and to promote a clean and green state.

The government has been focusing on promoting clean energy - solar photovoltaics (SPV) and wind power plants on rooftops across the state in general and Bengaluru in particular.

The net-metering scheme encourages individuals and institutions to take up solar photovoltaic power plants. It helps generate own power, reduce dependence on utility companies and sell excess power to the grid. Similarly, for the utility company, solar photovoltaic plants reduce peak-hour load, save their own energy, and reduce transmission and distribution losses as the power is connected to the grid at the site. Above all, it reduces pollution as solar and wind energy are non-polluting and renewable, unlike thermal power plants. 

The state government in order to encourage citizens to adopt solar energy has already made it compulsory to install solar water heaters on any building exceeding 600 sq feet without which power connection is not given.

But Bengalurians don't seem to be interested in setting up solar plants on their rooftops. In the last two years, after the revised Karnataka Solar Policy (2014-21), Bengaluru Electricity Supply Company (Bescom) has serviced just 250 rooftop projects with a total capacity of just under 5 MW.

Wind energy generators with hybrid windmill hasn’t even crossed three digits in Bengaluru. The cost of a hybrid wind power plant is 30% more than the conventional solar photovoltaic power plant while the average power generation is less than the solar plant.

The government buys power at Rs 9.56 a unit from those who have not availed subsidy and Rs 7.20 a unit for those who availed subsidy from the Centre. "Cost and delay in rate of return are the main concerns,’’ says Jagadishchandra Shetty, director Greensol Renewable Power Pvt Ltd. His company set up a 400 kV solar photovoltaic power plant on the roof of Chinnaswamy Stadium in Bengaluru.

C Nataraja, Bescom general manager (Demand Side Management) concurs with Shetty. "We are getting more requests from institutions and not from individual households," he says.

At the present market rates, one has to invest anywhere between Rs 80,000 and Rs 1 lakh to generate 1 kilo watt (kW) of energy. The space required is approximately 10ft X 10ft. A 1 kW plant can generate a maximum of 5 units of energy a day and can meet the energy needs of a medium household while a 2 kV plant helps run all electrical appliances - refrigerator, washing machine, mixer grinder, 1 or 2 fans, 3 to 4 lights and 1 AC for 6 hours a day.

The investment, however, will come down when one goes for a bigger plant. For one MW plant, the investment per kW is around Rs 60,000. The rate of return is also quicker,’’ Shetty points out, saying that one can breakeven in five years.  It, however, requires 5 acres space and Rs 6 crore investment to generate 1 MW solar photovoltaic power.

The government has set Bescom a target of adding 100 MW rooftop solar photovoltaic power plants a year. ``We are getting a lot of applications from outside the BBMP limits,’’ Nataraja says, expressing confidence of achieving the target.

Both Shetty and Nataraja say that with 30% subsidy for institutions and individuals extended by the Ministry of New  Renewable Energy (MNRE) and declining cost of solar photovoltaic panels and invertors more people are likely to go for rooftop SPV and wind power generation.

The government has sanctioned Rs 67 crore to Bescom to install SPV power plants on its buildings like Vidhana Soudha (70 kW), Raj Bhavan (20 kW), MS Building (70 kW), Visveswaraya Towers (120 kW) and others in the coming days. Bescom has also appointed two agencies to give a feasibility report on installing rooftop SPV plants in several other government owned buildings.

Vikasa Soudha already has a 100 kW solar photovoltaic unit installed long ago. Besides these proposals, Bescom is installing solar photovoltaic power plants on its buildings and a wind and solar hybrid at IAS officers association and at the Karnataka Urban Infrastructure Development Corporation Building (KUIDFC) at Indiranagar.

Solar Suits Karnataka
State has 240 to 300 sunny days a year with good solar radiation f 5.4 to 6.2 kWh­/m2/day. Assessment on solar potential in Karnataka estimates the energy potential at 20GW. Considering factors like availability of waste lands, evacuation infrastructure etc, the moderated potential may be around 10GW, says the State Solar Policy.

A joint venture company - Karnataka Solar Power Development Corporation Ltd (KSPDCL) by Karnataka Renewable Energy Development Limited (KREDL) and Solar Energy Corporation of India (SECI) to promote solar energy has been set up.