พลังงานแสงอาทิตย์ทางเลือกที่ควรถูกทบทวน
With the impact of oil prices likely to be seen soon in consumers' electricity bills, attention is focused once more on finding other sources of energy.There has been much talk about alternative fuels such as gasohol, liquefied petroleum gas and bio-diesel from coconuts and palm oil. But these too depend on finite resources. The sun provides the only free, clean and limitless energy.
Solar cell systems can substitute for electricity used in homes, offices, hospitals, factories and even in cars. But as long as conventional fuels are available, incentives to develop solar energy tend to be limited and costs are high.
The government has initiated a solar home system project, the so-called Ua-arthorn electricity programme, with a goal to light up every house in Thailand, particularly in remote areas that lack access to mainstream electricity.
However, owners of housing units in urban areas where electricity from the national grid is available could also benefit by installing a hybrid system that combines solar energy and a conventional electricity supply.
The system allows the homeowner to use the electricity generated from the sun and sell any left-over power back to the Electricity Generating Authority of Thailand, explained Dr Porponth Sichanugrist, director of the Energy Technology Centre at the National Science and Technology Development Agency.
A key component is a bi-directional electricity meter that can be run forward and backward, so the process of sending excess electricity to a utility would automatically rewind the meter to show lower use of electricity.
The conversion is not cheap, Dr Porponth noted. ``With a high initial cost of about 800,000 baht a house, solar home systems are not popular among Thais. But it will be more advantageous in the long run when we are in an energy-shortage situation,'' he said.
The investment includes a 400,000-baht converter, the meter, electrical lines and 30 solar panels that can produce up to 1,000 watts per hour of electricity, sufficient for general use in a house with up to three air-conditioning units.
Currently, there are 50 solar homes in Bangkok but they involved the installation of solar cell panels on a conventional roof which are not as efficient in generating electricity, said Dr Porponth.
``Building a new house with a solar cell roof is more advantageous than installing panels on the existing roof because a flat panel solar collector has to be installed inclining 15 degrees to the south for the best solar reception. A solar cell roof can also reduce the heat in the house.''
He pointed to the success of the system in Japan where there are a total of 65,000 solar homes. The world's first and largest solar city is in Kiyomino with 79 solar homes. Each can produce three kilowatts of electricity or up to total of 222,665 units per year.
The Thai government also has ambitions to build a solar city when it develops Nakhon Nayok as a new administrative centre, with solar homes to stimulate the use of solar cells and promote the new city as environmentally friendly.
Dr Porponth said the biggest obstacle is the cost of production. Producing solar cells is still very expensive as the components need to be imported.
The Energy Technology Centre has received approval for a two-billion-baht budget to conduct the research and development of solar cell production to reduce the cost. The study will start in 2005 and run until 2012.
``If the government helps subsidise the cost to boost demand as in Japan, while we can develop the efficiency and materials of solar cells, the solar home system could be widely used in Thailand at a low cost,'' he added.