Power from solar grid can resolve power shortages in small towns

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The most attractive features of solar energy are its omnipresence and the fact that it comes free. The current photovoltaic (PV) solar cell may have an efficiency of just about 17-18 per cent, but what matters is its ability to transform solar energy into usable electrical power from a free, non-polluting energy source.

By P S Deodhar

Friday, October 15, 2010:  Currently, PV solar energy is indeed the best option since no better technology breakthrough (that’s usable on a mass scale) is in sight. The credit, therefore, goes to the government for taking a bold initiative and setting an ambitious target of generating 2500 MW of solar electric power by 2012 and 20,000 MW by 2020. The primary aim of the Jawaharlal Nehru National Solar Mission (JNNSM) is to speedily augment the inadequate electrical power that’s hampering inclusive development.

The sun delivers more energy to the earth in one hour than what the world currently uses in a year. It is omnipresent, wasteless, renewable and free. Therefore, primarily it is the innovativeness of policies that will enable us to realise our dream of a cleaner and greener India. The nation will benefit from huge productivity gains due to availability of reliable power to our people by just focussing on one important feature—it is free and available at any place. We have solar grid to get rid of our total dependence on the copper grid.

Power shortage blues

People in smaller towns and those in rural regions like farmers, artisans and their children are worst affected by power shortage and its quality, from the copper grid. There is a huge majority of communities in hinterlands where copper grid has not reached even 63 years after Independence. Working people suffer from productivity loss since rural economic activity currently stops at sunset and thereby each rural household loses close to 15 man hours each day.

In the rest of the country, the quality of power reaching consumers and businesses is ridden with problems of long blackouts and wild voltage fluctuations. Due to this, there is not only a huge loss in national productivity but it also causes malfunctioning and total destruction of power appliances, machinery and light bulbs.  Solar power can correct this since unlike a copper grid, a solar grid is available even in the deep hinterland. This would be preferable than to wait for the copper grid that indeed is a long term project, with its associated operational delays.

Unfortunately, our objective to improve power reliability and quality in small towns will not be realised with the current PV solar power policies. Unless the current policy undergoes important changes in order to quickly exploit and benefit from the omnipresent solar power to augment the weakest links in the copper grid, much time and money will be lost without any benefit to the target group—people living in villages and small towns.

With changes suggested in this article, we can meet the mission’s objective to make available stable, reliable and uninterrupted power to a vast population that lives outside metros and big cities. Let us examine these issues in depth.

Policy lacunae

The current policy focus is to start with large solar power plants. That’s why, today it allows power purchase agreement only with large solar energy plants of over 1MW capacity feeding power into a 33kV grid but nothing to smaller solar plants, 5kW and above, as is done in every other solar country—US, Germany, Spain, etc.

About 33kV and higher portion of the grid are basically a ‘low impedance nodes’ and, therefore, has more stable voltage than at high impedance nodes from where small towns and rural areas are served—from 11 kV and a lower voltage grid, primarily since these have high line impedance. The feeder current capacity is mostly inadequate as one goes down to 440V feeders. Usually, huge losses of power occur at these fag end delivery points of the grid. An impedance analysis of the power grid done by the IEEE reveals that injecting alternative power at high impedance nodes speedily improves the resultant power quality in the neighbourhood, rather than feeding solar power at low impedance nodes. That’s why in countries like Germany, Spain, US and China, grid feed is allowed even in a 230V single phase line from even 5 kW solar power generators.

The two biggest problems of all consumers in small towns and rural areas are blackouts and poor quality fluctuating power. Big industrial customers drawing power from 33kV lines or higher grid points generally receive good quality power. Those receiving power from low voltage feeders suffer the most. It is true that the solar energy delivered into the 33kV grid will provide additional power from solar plants but this addition of 2-3 per cent power fed at these low impedance high voltage grid nodes will not, unfortunately, improve the quality of power that people in non-metro areas chronically suffer from. It is important for the Ministry of New and Renewable Energy (MNRE) to think why, unlike India, every other country in the world allows solar power to be fed into the grid even at 230 V. We need to understand why.

Business paradigms

The first important need for growth of PV solar power usage is to ensure that even small power feeders get PPA to sell the power that they feed in. Without adequate return on investment, people would not venture to invest in rooftop and backyard plants in capacities of 5 to 10 kW and above. One would not see investments in solar power in rural areas and small towns—the places where grid fed PV solar power will make greatest sense. It is essential to load these plants to their full capacity when the sun is shining. ROI will be attractive if all the harvested power is sold. This is possible only when the plant is fully loaded at all times to its maximum harvesting capacity throughout the time the sun is available. Benefits of this are many and attractive in several ways.

First, solar power generated locally in power starved areas and fed into the terminal points of local grid will improve faster when injected power is above 30 per cent of the local consumption. This has been proved in rural areas both in the US and Europe.

Second, in most of such locations, undesirable use of lead acid batteries can be totally avoided. Why should one store energy in batteries if one can feed it into the grid and draw what he needs. Batteries will then be used only where the grid is absent. We essentially worry about excessive use of lead as it is a deadly pollutant.

Third, for us medium size grid tied rooftop and backyard plants in small towns will be far better rewarding than the big ones. For example, in the US, the total grid tied rooftop PV solar power projects grew by 81 percent in 2008 (to 196 MW) and an additional 93 per cent in 2009 (to 385 MW). The fastest growing solar industry sector was the non-residential rooftop and backyard market that grew at 109 per cent. This segment includes rooftop PV solar installations for commercial and government buildings, factories, warehouses, schools, colleges and universities. In fact, solar power projects have grown by over 62 per cent a year for the past five years in the US.

There are great merits in promoting the growth of solar plants especially on rooftops and backyards lying unused today. Let us consider how many thousand square kilometres of rooftops and backyards in the country currently lying unused? Like in the US, India too has commercial and government buildings, factories, warehouses, schools, colleges and universities with very large unused terraces and backyards. We can have at least five gigawatts of solar power pushed into the grid from small towns to augment shortages.

Fourth, off grid plants make little sense when grid power is present even if it is intermittent. Self use power is never even 40 per cent of plants harvesting potential since plant power is designed to meet the peak demand. If all such off grid plants are eligible for grid feed, the country can harvest full available energy from each plant. Only when all such excess power is injected in a grid can more solar power be harvested from investments made by the country under the JNNSM scheme.

Huge private investments will be made only when an identical subsidised rate per unit is paid to smaller grid fed solar plants for the excess power that such plants will have. This is what has happened in advanced nations like the US, Germany, Spain and China. The energy needed in small, non-industrial towns is at night. So, say, a 50 kW plant with grid fed capability can deliver power into the local high impedance grid during the day and draw that power at night. So, to bring about quick improvements in the availability of quality power in energy starved areas, our best option is to follow the Europeans and Americans and feed solar power into a local low voltage grid.

The technology to measure such an energy feed is universally established and is in use everywhere in the world, enabling the power utility to pay those who feed solar power into the grid.

Other reasons to promote distributed solar power generation

There are many more reasons to promote distributed solar power generation, rather than buying solar power only from big plants of 1 MW and above. Most important among them is that there is practically no financial advantage in having just the large plants. The cost per watt of solar power remains the same, irrespective of the size of plant invested in. Setting up a 10kW plant will cost just 10 per cent of the cost of a 100kW plant; or the cost of a 1 MW plant will be 10 times the cost of a 100kW plant. This is because the basic PV panel constitutes a significant part of the plant’s cost and its power capacity is about 250Wp to 300Wp. One just has to add more panels to build a larger plant.

Supports power SME growth: Since the economies of scale do not operate to any advantage in this particular case, experts consider distributed generation to be a better concept than generating in bulk. This, in turn, means that such smaller but more effective solar energy plants could be created by medium sized enterprises to service local areas, creating local jobs.

Distributed feed advantages: Consider a 10 to 50kW solar plant in areas near a town feeding their power into the local lower voltage grid. Let us remember how grid behaves. Injected energy will find its way to meet the local demand first. This will immediately improve the stability and reliability of the power available to the local people served from that feeder. In such a case, many local investors will come forward to invest in several smaller power plants within a town or a village. Investment in all these plants will also be profitable when the government buys power from these plants at the same rate that they currently pay to big plants feeding power into the 33kV grid.

If an industry in a small town sets up a 50 or 100kW plant for its own captive use, it always has a lot of excess power to feed to the grid. This excess solar power will not only help the country harvest more power but also load such plants to their full capacity so long as the sun is shining. Once this happens, a large number of local entrepreneurs will set up such small plants. The experiences of solar power installations across the world show that smaller solar power plants are easier to maintain than bigger plants. This also helps in generating local employment.

Utilisation of unused spaces: Another major problem with solar power plants is that unusually large area is required per kilowatt of power. As much as 1 sq m of space is needed to generate 100W of peak power. The location has to be such that there are no trees and tall structures casting shadows on a solar array. The place also needs to be secure and free from birds and monkey menace. It is easier to find such locations in barren non-arable land around towns and rural areas—each accommodating plants of 10 to 100 kW plants. Imagine how many thousand sq km of terraces and backyards even in public and government buildings remain unused or used as garbage dump. All these are ideal to install solar plants up to 50kW. SMEs could be given these spaces helping them to get into power generation business. Government should seriously use this opportunity to ensure that SMEs benefit from solar opportunities as much as big corporate enterprises.

Is the policy unfair to small enterprises?

The government should not forget that one can challenge the current policy of buying power only from big solar plants in which only large corporations can invest money. Suppose local people invest and develop power with a 20kW plant set up at a remote village to provide power to 50 to 100 hamlets, how can they be denied subsidies at the same rate that a big corporation gets for producing over 1 MW of power. Today, we just dole out capital subsidy and that is no match to annual revenue if the solar power is fed into the grid. One can be sure that our laws will not allow the government to discriminate and deny equal opportunities to all entrepreneurs. In fact, a village that invests in its own power plant needs to be encouraged since the state has been unable to invest and feed power to that village. Before the matter reaches that legal tangle, it is better that the government looks at its subsidy policy and ensures that there is justice for all.

The author is former chairman, Electronics Commission, Government of India and advisor to Rajiv Gandhi

Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine

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