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How to power up the rooftop

According to reports, except the nice feeling, Dutchman Toine van Megen, an Indophile who has been living in this country for over 40 years, gets nothing for the electricity he pumps into the grid from his rooftop solar power plant.

If everyone could afford to be like the former executive of Suzlon and the co-Founder of Auroville Consulting, there would be a vibrant solar rooftop movement in the country.

Today, industries, educational institutions and commercial establishments such as shopping malls are putting up rooftop solar — for reasons as diverse as depreciation benefit, meeting renewable purchase obligations, and energy security.

However, very few home owners have taken to it, because domestic rooftop solar just does not pay.

The case of Tamil Nadu is illustrative. You can put up a 1 kW solar plant under the State’s capital subsidy scheme, or avail yourself of the State’s generation-based (tapering, six-year) incentive, or just not opt for any subsidy or incentive, which is the only option available if one wants to go in for more than 1 kW system.

Calculations (available on show that the returns are 4.7 per cent with subsidies from both State and Central governments, 1 per cent with Tamil Nadu’s generation based incentive and minus-2.35 per cent without any subsidy or incentive.

The situation looks better when electricity tariffs go up, but to counterweight that are a whole lot of assumptions — maintenance costs, generation, the uncertainty and the ‘cost’ of getting the subsidies. The only way to attract home owners to put up rooftop solar is to pay a remunerative feed-in tariff, which could taper over time, says Vivek Jayakumar, Executive Director, of the Pune-based Arbutus, a solar consultancy.

By Auroville Consulting’s calculations, an investor will get a 15 per cent return if he gets paid Rs 11.50 a unit. The expenditure would be defrayed by levying a small green cess — 1.08 per cent for the first five years, 1.94 per cent for the second block of five years and 0.26 per cent for the third.

At the highest domestic tariff, these translate to a rise of 6 paise per unit for the first five years, 11 for the second block and 1 for the third.

Do this, and you could have 15,000 MW of rooftop solar in the State in 15 years. And knowing that is a nice feeling.

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