Rooftops as power houses

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Power from the sun.
Power from the sun.

Rooftops are set to play an important role in enabling energy security by tapping renewable resources.

R. Balaji

Rooftops are to go green. No, this is not about setting up roof gardens but a more high-tech form of harvesting the sun's energy — through solar power generation systems.

Come Monday, the Ministry of New and Renewable Energy (MNRE) will make available applications online for pre-registration of projects to set up grid-connected rooftop and small solar power plants.

Project proponents will be able to preregister on from 11.00 a.m. onwards, says the MNRE's Web site. This will be the first step to accessing the massive subsidy planned and attractive tariffs being provided by State electricity boards to promote use of solar energy. The online portal, for registration and initial short-listing of rooftop projects, will be activated from noon of July 15.

This is an initiative under the Jawaharlal Nehru National Solar Mission of the Government of India to set up 200 MW of off-grid solar power for rooftop systems by 2013 and about 100 MW of grid-connected power backed by generation-based incentives. The Rooftop Photovoltaic and Small Solar Generation Programme is expected to meet with enthusiastic response from investors.

Generating interest

In Tamil Nadu, according to officials, there are more than 100 potential investors hoping to tie up for grid-connected solar power projects.

Apparently rooftops will no longer be uninteresting, used merely for drying laundry or cluttered with plumbing materials and remnants of concrete pillars.

Mr K. S. Sudarshan, Chief Operating Officer, Ozonegroup, which is setting up a 42-acre self-contained township in Chennai, says the rooftops of the buildings at the township, Metrozone, will house over 1 MW of solar power generation capacity at an investment of over Rs 20-25 crore. This would be an off-grid set-up. The real-estate developer is also planning 0.15 MW and 0.75 MW of solar power facilities at its projects in Bangalore which could be linked to the grid.

Ozonegroup sees it as a viable project supported by the 30 per cent capital subsidy from MNRE, assured and maintenance-free source of power that is insulated from cost escalation.

Carbon revenue under the Clean Development Mechanism will be a potential source of revenue, he said. Power from the solar generation unit would be supplied to residential and commercial spaces in the township, apart from being used to light up the common areas.

Cost equation

Mr Balasubramaniam Mantha, Asia-Pacific Sales, Solar Semiconductor Pvt Ltd, while addressing a gathering at the Tamil Nadu Energy Development Agency, the nodal agency for promoting renewable energy in the State, said that State Governments plan to set up solar power projects in government buildings, and in the private sector, developers of commercial buildings, residential units, hospitals, hotels and theatres have evinced interest.

In the backdrop of a chronic power shortage in most cities and increasing costs of power generation from captive sources, solar power, a capital-intensive technology for now, is actually gaining ground.

Power from diesel generation costs about Rs 16 a unit and is going up by about 5 per cent annually. Grid-connected power costs about Rs 5.50 a unit for commercial users. But a 25 kW solar rooftop system pays for itself in six years and continues to work for nearly two decades after that.

A 25 kW system costs about Rs 60 lakh. MNRE's subsidy of Rs 18 lakh brings it down to about Rs 42 lakh.

This unit generates 41,250 units a year for 25 years with the equated yearly instalment working out to about Rs 2.94 lakh on an interest rate of 5 per cent (IREDA refinance). Compared to a diesel powered unit, the Net Present Value is Rs 1.15 crore. (NPV is Rs 12.49 lakh compared to grid power).

In commercial space

A spokesperson for Moser Baer Photo Voltaic, a leading manufacturer of solar energy equipment, said developers are one segment of potential investors looking at setting up grid connected or off grid solar power project using the rooftop space.

For instance, mall as well as residential project developers are looking at rooftop solar energy units. Retail space is a major power guzzler and developers are under pressure to exploit renewable energy.

DLF, which put up a solar unit at a mall in Gurgaon, is now looking at more such investments across its malls in various locations, the spokesperson said.

Malls are power intensive and are bound to look at renewable energy options. In addition, just about anyone who is interested in cutting back on power costs, including industrial units, is looking at solar energy.

Recently, Moser Baer commissioned a 200 kW rooftop solar photovoltaic power generation facility for Omax Auto, an auto components manufacturer.

While declining to give details of the costs involved, the spokesperson said that a unit like that would save the company about 30,000 litres of diesel, annually. The breakeven for the investment would be achieved in two years' time.

(This article was published in the Business Line print edition dated July 11, 2010)
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