Sunlight is omnipresent. Why, then, centralise such well-distributed energy into a multi-megawatt solar farm, and redistribute it, losing 25 per cent in transmission?
Guest Column
PS Deodhar, formerly chairman of the Electronics Commission of the Government of India, and the electronics advisor to India’s late prime minister, Rajiv Gandhi
Distributed solar power generation is the opposite of centralised generation. In centralised generation, electricity is generated at central power plants that are sometimes located hundreds of kilometres away from the load centre where the consumers are located.
Central power plants essentially need extra-high-tension (EHT) power transmission. As a result, these involve a high investment cost and suffer huge losses in transmission.
Distributed power generation is a method of generating electricity and other forms of energy from locally available energy sources such as sunlight, wind and biomass. They can meet the power needs of remote areas with the lowest investment, and also help to improve the quality of power in small cities and towns.
Distributed solar and wind energy generation can eliminate the need for inefficient ‘central’ solar and wind farms that are typically owned and operated by large electric utility companies. Small solar power plants can be locally owned by qualified small or medium enterprises (SMEs). These will also help to create much needed local employment.
Distributed power plants can cater well to the electrical power needs of a cluster of villages, ensuring power generation at the point of consumption, with zero transmission losses.
Distributed power projects directly benefit the consumers and it makes great sense to set up these where the power grid has not reached.
If the grid is available, small power plants with 5-300kW capacity can feed the energy generated at a low voltage into a local substation. This locally generated power will first feed the local loads and the excess will go elsewhere, ensuring the plant’s entire power generation capacity is used. Distributed power plants also have very little greenhouse gas emissions.
Locally available renewable energy projects can deliver in just a couple of months compared to two to three years, typically associated with larger-scale developments, and probably at a much lower cost.
Why then centralise such well-distributed energy into a multi-megawatt solar or wind farm, and redistribute it, losing 25 per cent in transmission? Further, why use large and expensive land resources adding to ecological problems, as well as the costs?
India has so far not focused on rooftop solar installations. This has to change since this approach is both a great environmental strategy as well as a sound business strategy. While each individual solar project would be smaller than a large-scale project, one has to remember that mini power plants today deliver over 1800 MW across North America and Europe.
In short, for the National Solar Mission 2020 to succeed, policy makers will have to view solar power generation from a developmental perspective. Energy security and rural electrification will get a huge shot in the arm from solar power projects that can quickly come up across the country as part of the current policy drive. Efforts are also required to promote community-based awareness, especially in rural areas.
The present situation
Solar energy generation is perfectly suited for India compared to many other sunlight-starved countries. The government has made a start by fixing an ambitious target of 22 GW solar capacity by 2022, which rivals that of China. However, the first phase of the Jawaharlal Nehru National Solar Mission (JNNSM) has mainly given subsidies and incentives to multi-megawatt solar installations and inexplicably ignored more appropriate distributed solar projects, which are widely promoted in countries like the US, the UK and Germany. As a result, in the last two years, India saw a flurry of multi-megawatt (2-200MW) PV solar power plant announcements—mostly with foreign technology and designs. Despite this, the JNNSM is nowhere near its 2012 target.
India desperately needs more renewable energy for hundreds of millions of homes and businesses in places where the power grid has not reached.
According to government reports, 400 million Indians today have no access to grid power. Giving them just a solar lantern will not serve any purpose. There is no better way to give electrical power to them than to exploit the local availability of sun, wind and biomass— focusing on distributed small-scale projects. Distributed small-scale projects enjoy important advantages over large-scale projects. These are less complex, faster to interconnect and bypass time-consuming land-use issues that often add years to project timelines.
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No transmission losses. Grid-connected multi-megawatt solar farms with capacities of 11kV and above not only suffer from the average distribution loss of 15 per cent (20 per cent on the power grid, not counting 10 per cent additional loss in theft) but also a further loss of 3-4 per cent in stepping up the expensive solar power generated at 400V.
Distributed solar, on the other hand, can use existing low-voltage transmission in a local substation, avoiding this 20 to 25 per cent loss of high-cost solar power. Distributed solar power of up to 2-300 kW is produced at a low voltage (400V AC, three-phase) and can be either distributed by a local mini-grid (if away from the National Power Grid) or fed into the substation of the National Power Grid.
Less expensive. There are no economies of scale in solar power generation from multi-megawatt solar plants. Costs of PV solar plants scale linearly from kilowatts to megawatts. So project management and land costs make multi-megawatt solar plants more expensive.
No restriction on location. Solar photovoltaic (PV) technology is clean and quiet, which means it can be sited on or within a locality. Distributed solar is also easy to adapt to site conditions and scalable to existing transmission capacities.
Mini grid protocol. Many small plants can be progressively linked via the small generator interconnection protocol (SGIP). The result is that distributed small-scale projects go through a quicker review and are less likely to encounter huge delays and bureaucratic wrangles while waiting for lengthy power grid extension.
Costs less than extending the National Power Grid. The 2003 plan of India’s Ministry of Power to extend grid power was abandoned because the investment required per house was Rs 23,000. In 2012, that figure would have doubled. With a local mini-grid, this cost will be much below Rs 20,000. More importantly, the energy is free of cost.
Grid stability. A large part of distributed solar power is consumed locally. Multi-megawatt plants, on the other hand, supply 100 per cent to the grid. Managing the grid becomes difficult with the increase in solar power penetration.
Less use of environmentally-sensitive land. Unlike large-scale solar projects, distributed small-scale projects don’t need thousands of acres of pristine wilderness. Instead, they can be sited on large industrial rooftops, unused terraces and backyards. This means they get through land use approvals and permissions faster.
High-voltage grid feed of solar farm power has only marginal benefits. Energy from 2-50 MW PV solar plants fed into the existing power grid is just a tiny fraction of power flowing through it. So it in no way substantially improves the supply. This small addition makes little difference in terms of solving the problems of blackouts and brownouts that consumers suffer. The hours of power loss will continue.
Low-voltage grid feed of distributed power helps 100 per cent use of solar power. PV solar is relatively expensive and when it is fed into the grid at EHT levels, it suffers a high transmission loss of over 25 per cent. So the cost of useful solar energy goes up by 25 per cent. In distributed solar plants, almost all the power generated is available for use.
Distributed solar power helps to create power SMEs. Distributed solar power from 50 kW-300 kW solar plants creates opportunities for SME investment in solar power generation. This will trigger local employment and open avenues for new local entrepreneurs.
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