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BW Businessworld

Bright Future For Solar Rooftops

Solar power plants may face acute problems in India, but rooftops will succeed by Rajendra Shrivasrav

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Rajendra Shrivasrav

I am deeply committed to development of solar power in India. I support all efforts to add solar generation capacity from MW size solar power generation units connected to the grid and from teeming small size rooftop installations connected to homes. There is no competition between the two types.

I supervise installation of rooftops for internal consumption of electricity for industrial companies in Haryana. These rooftops will save these companies from buying a certain percentage of power from the state grid at the rate of Rs 7.5 to Rs 8 per kilowatt hour. This tariff, prescribed in 2015, will increase at the rate of seven per cent a year in the coming years.

The rooftop investment viability is based on the avoided cost of buying from the grid, and needs no subsidy from the central or state government. Rooftop solar units power the owner’s premises — the last mile of the discoms’ supply — and hence strengthen the distribution network of the discoms. They also cut carbon dioxide emissions. A 100 KW rooftop solar unit could save 3000 tonne of CO2 over its 25-year lifetime.

I believe the future of ground-mounted large-capacity (50 MW and above) solar power plants in our country will face acute challenges, such as grid disturbance problems, the lack of capital investment by the government to provide an exclusive green transmission corridor, expensive battery banks to support photovoltaic plants supplying into state-owned transmission networks, and high-decibel politics between the state and centre. In this melee, rooftop devotees will race ahead of big-ticket solar plants in India.

Just imagine, rooftop units will democratise investment in solar power, and millions of Indians can become stakeholders. Compare this to the limited number of public and private-funded companies (50-odd Indian and global investors) involved in setting up large MW scale solar plants in India. India’s rooftop target is 40,000 MW, and ground-mounted solar generation target is 60,000 MW. It requires more than four lakh acres of unencumbered land to reach this target. A lot of roof is available, but not enough land banks, for setting up tens of thousands of large solar projects.

The often touted claim of Rs 5 per kilowatt hour from solar developers is not the real cost of photovoltaic generation. It is only the price of solar electricity offered by the developer to the state. But for solar plants to operate in any state, the central or state governments, and their power generation and transmission companies, must bear indirect and direct costs, to save the grid from collapse due to the un-schedulable nature of solar and wind power. This is the real challenge in India, and the big limitation to reach 60,000 MW target in coming years.

In this context, it is instructive to recall the order passed by V. S. Verma, Member, Central Electricity Regulatory Commission (CERC) and Adjudicating Officer, on 10 August 2010, on a matter between TNEB and Southern Regional Grid Management. His deep anguish and frustration about lack of grid stability is worth a read (Adjudicating Case No. 1/2010) on the subject, “Maintaining grid security of the Southern Regional Grid by curbing over-drawals and effecting proper load management by TNEB”.

The order details how grid stability was threatened for weeks by renewable energy (wind power plants). TNEB blamed its overenthusiasm to add wind power in their grid and expressed regret for doing so. The threat to grid frequency and Unscheduled Interchange (UI) will increase and grid collapse precipitate in any state, once the solar power plant installed capacity starts exceeding 10-15 per cent of the total grid capacity. In states with solar plants and wind power, they add up to increase the threat of grid collapse. Availability-Based Tariff (ABT) and UI mechanisms of electricity regulators go for a toss once solar adds between 2,000 MW and 3,000 MW in most of the states.

This is a real worry. The CERC document, available in the public domain establishes with clear data and statistics, the limits of sudden loss of power in MW for typical state grids, irrespective of the reasons for such a drop.

Some of the typical states as listed by CERC: (1) Maharashtra grid 19,804 MW (250 MW power drop limit), (2) Gujarat grid 13,499 MW (250 MW power drop limit), (3) Tamil Nadu grid 13,498 MW (250 MW power drop limit), (4) Uttar Pradesh grid 13,003 MW (250 MW power drop limit), (5) Rajasthan grid 10,642 MW (250 MW power drop limit ), (6) Punjab grid 10,023 MW (200 MW power drop limit). The figures in brackets are statutory limits of disappearance/drop of power supply to the state grid, else the grid frequency will take huge hit, and grid management by state and regional load dispatch centres will become unmanageable.

The question is: Will solar power not add thousands of MW each morning, and this much solar power will disappear by evening, threatening the survival of the grid it is connected to? I have serious doubts whether large capacity grid-connected solar power plants or solar parks are sustainable in the Indian grid. Over time, as solar grid-connected capacity increases, big solar plants will be shunned by state utilities, and for those that are already in business, the power purchase agreements will not be worth the paper they were written on.

The author is former MD, Alstom (Nuclear) and Country Director of EDF in India. He currently advises companies in the alternative energy business

(This story was published in BW | Businessworld Issue Dated 28-12-2015)