Millennium Post

Harnessing the Sun

Harnessing the Sun
India appears to be waking up slowly to harness sunrays from rooftops. From nascence, the concept of harnessing the Sun from rooftops is yet to move the public mind. However, recent initiatives by a few government organisations signal some movement in this direction. Conversely, ground-mounted projects under the National Solar Mission (JNNSM) have registered an incredible growth – a strange paradox. Large scale ground projects demand vast tracts of expensive land, while rooftops are wasted spaces – free and easily available.

The Delhi Metro’s decision to mount rooftop panels to tap sunrays for satiating its power needs is a welcome initiative. Using the vast sun-drenched areas under its jurisdiction – at stations, parking lots and residential complexes – is a step in the right direction. Each station is slated to produce about 500 kWp or peak power (between 1,750 and 2,250 units of electricity per day).

This followed the recent inauguration, in the national Capital, of the Indira Paryavaran Bhawan, the ‘net zero energy’ green building (housing the Ministry of Environment and Forests), with 930 kWp rooftop solar power plant for cent per cent power generation. These signify a more serious intent in implementing the green growth agenda set by the National Solar Mission, which is a part of the National Action Plan on Climate Change (NAPCC).

On the other side, in a brief span of three years, ground-mounted solar projects under Phase I (2010-2013) of the solar mission and by state governments have taken a major step forward. From a meagre 30 MW, the installed capacity of solar power in the country has crossed 2000 MW. Being implemented in three phases, Phase-1, which focused mainly on grid-connected MW-scale solar projects, is well-poised to make India a global leader in solar power generation. Also, several state governments have declared their own state-level solar policies. The aggressive participation by the private sector has already resulted in the dramatic fall in solar tariffs, from around Rs 18/kWh to about Rs 7/kWh.

However, solar rooftop projects are still in a developmental phase. Most commercial buildings, malls, hospitals, offices as well as residential buildings, which opt for diesel generators as power back-up, are yet to unlock the value in their vacant terraces in a big way. Many are not aware that they can either set up their own solar energy generation system or lease space to developers. In this method, known as rent-a-roof scheme, the project developer sets up the complete PV system on the owner’s rooftop and sells the electricity generated to the discom which feeds it to the grid. The roof owner either gets a fixed rent or a share of the profits the developer makes. Rooftop installations have several advantages over-ground mounted projects. They are connected to the distribution system and power is ingested into a load centre. This avoids transmission and distribution (T&D) losses, nearly 30 per cent, incurred in centralised, larger plants. They create economic value for unutilised rooftops, do not face land availability issues like ground-mounted projects, and have a very high self-replication potential.  More importantly, solar rooftops can massively reduce consumption of diesel, used in back-up power across the country.

Despite these advantages, roof-top installations, targeted at 2,000 MW by 2022, is progressing at a slow pace. To encourage in-house consumption and to replace diesel power generation, the Ministry of New and Renewable Energy (MNRE) is implementing grid-connected rooftop projects in 19 select cities across the country. Systems varying from 100 kW to 500 kW are being installed.

Consumers pay 70 per cent of the cost and the rest is given as subsidy by the Ministry. The condition stipulates that systems must be grid-connected and should not have a battery back-up. A major deterrent in going solar is the prohibitive cost. A rooftop system that would energise domestic appliances such as lights, fans, television and computers may cost between
Rs 60,000 and 1.5 lakh. Further, serious thought has not been given to an integrated approach. ‘The small scale rooftop market is not organised,’ says Dr Tobias Engelmeier, Managing Director and Founder, Bridge to India.

To make the projects viable, some states, especially Chhattisgarh, Kerala and Gujarat, Tamil Nadu, are providing incentives in addition to the central subsidy of 30 percent. Rooftop projects in States rely largely on the MNRE for financial support. The forthcoming elections have led to a funding crunch and there is no certainty of these schemes going through for most part of this year.

Further, provisions for net metering, that will offer better financial incentives to solar-power generating households, have been introduced by eight states. Gujarat is set to implement net metering shortly. Under this policy, an electricity meter, that measures the power consumed by a household from the grid, and the power supplied (from the solar rooftop) to the grid, will be installed at homes. So, if a household generates 100 units through its rooftop solar panel and consumes 200 units of electricity, it will have to pay for the excess 100 units. In case, a house produces more than their requirement (at any given point in time), the additional power will go to the grid, for which the consumer will get a credit.

Any amount of power generated from renewable energy sources, like solar, would prove inadequate unless households, ritzy offices, government and commercial buildings, which bathe in incandescence conserve electricity. Corridors of power need to emulate the Environment Ministry and avoid waste of wattages. Passages and corridors may be fitted with time-switches, or switches coupled with motion sensors that will turn on lights only on sensing human presence. Even after the last train reaches its destination, metro stations keep the interiors illuminated till dawn, perhaps for security reasons, thus wasting enormous power. The axiom ‘a penny earned is a penny saved’ is more valid in energy conservation.

The author is an independent journalist
K V Venkatasubramanian

K V Venkatasubramanian

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