Solar energy could ensure continuous electric supply during 2020 dry season!

Convert to Solar Power!

An important crisis for the Government of Sri Lanka (GoSL) dealing with a faltering economy, is that related the power generation. For not a single power plant has been constructed in the past five years; with very long lead times for power projects, it mean that generation of electricity lags seriously behind the need. The Ceylon Electricity Board (CEB) may close the gap by purchasing power from private power producers, which would result in high costs of electricity and colossal expenditure for the state. Whereas part of the solution could come from solar energy, as it is envisaged adding 800 MW of solar energy to the national grid with public-private partnerships in high-insolated regions of the country, such as Pooneryn, Mannar and Moneragala. Also with the encouragement, within the next five years, of roof-top solar power systems, by making available to households and small businesses, bank loans with low/concessional interest rates, giving them access to low-cost energy. Also many holistically ‘green’ proposals to promote such agricultural water-conservation systems as drip irrigation and sprinkler systems, through the Agrarian Services Department, saving on fuel by enabling tax free importation of solar powered water pumps and solar photo-voltaic (PV) cells.

Certainly, solar PV cell installations are much easier to set up than other forms of power plants. The proximity of Sri Lanka to the equator means that sophisticated tracking devices may not be required in most cases, a simple stand for a panel array often sufficing, so no large-scale construction is necessary – especially in the case of rooftop-mounted PV panels. An electricity-generating system based on PV panels may, hence, be installed quickly and economically in locations with high insolation.

However, hitches may arise in connection with the distribution of the generated electricity. Solar power is intermittent, not steady. The quantity of power produced depends on the amount of sunlight available, which can vary according to cloud cover, and to the time of day. This requires some method of stabilisation to make the power usable. But the biggest problem of all is that Sri Lanka, not possessing a great deal of industry, uses very little electrical power during the day.

Unfortunately, power consumption peaks in the evening to night hours, between 6 p.m. and 9 p.m., when people switch on their lights and other domestic facilities; that more than double the off-peak demand, causes energy planners the biggest headache of all. As the abundantly available and cheap power of the sun cannot be used during this peak period; to end the energy crisis using solar energy requires some kind of storage. Storage would also solve the problem of stabilizing the intermittent supply.

Batteries could be used, but they add to the expense, and their disposal or recycling creates additional expenditure. South Australia has installed a 100 MW Tesla battery storage system, intended to stabilise the system, which has reduced considerably on the cost of electricity for consumers. Now it plans to expand this capacity by 50 MW, to bring the total storage capacity to 193.5 MW hours, and make the battery system capable of replicating some of the features of a traditional coal or gas power station. There is still the draw back in that, this system may well be too expensive for Sri Lanka.

The government has, for some time, considered another storage alternative, a scheme for pumping water into a reservoir, to be released through a hydro-electric power station. It planned a 600 MW plant and storage reservoir, costing US$ 800 million. However, no action has been taken to implement it.

What the government has not, hitherto, considered is solar thermal power plant, with heat storage – which retains sufficient thermal energy to enable generation well into the peak hours. Such plants cost much more than solar PV cells, but are becoming cheaper. The cost would probably be less than that for solar PV cells combined with electrical storage facilities. There were two more, related proposals made: first was to take action to develop sea-water based refrigeration systems for multi-day fishing craft, encouraging the use of solar power in such equipment; and the second was to experiment with introducing small-scale solar-powered refrigeration facilities for the storage of milk.

Earlier, the concept of using solar power for refrigeration originally saw development in Sri Lanka in the 1960’s, when J.C.V. Chinappah developed an ammonia-adsorption refrigeration system. Unfortunately, the system failed to be recognized in its home country, but did find use overseas, in cool rooms and ice machines. The implementation of the solar-power related proposals may well kindle a revival of the spirit of experimentation, which gave birth to Chinappah’s solar refrigerator.

At present, there are over 600 applications from small-scale solar producers (under 5MW) having registered by paying over Rs. 1,000 million for over three years, capable of supplying 1,500 MW of solar power. However, the CEB has refused to accept, quoting a conflict in regulations. The tariff approved for solar power below 5MW is Rs. 23.10 per kWHr, but CEB engineers claim the rate offered need be reduced as solar panel costs have come down in the world market.

A possible way forward would be to request solar-power producers to implement their proposals immediately and meanwhile remove conflicts in regulations. In addition, without reducing the agreed rate, incorporate five-hour storage batteries to allow solar power to handle peak demand during 6 to 9 p.m. If half of the proposed solar-power joins the grid early, the country would be able to tide over the power crisis until LNG power plants come into stream. For the greatest challenge for the Government is to ensure continuous electricity with minimal hydro power produced during the 2020 dry season.