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Thursday, February 16, 2012
Air-conditioning with direct solar
Air-conditioning is considered as a luxury, even in tropical countries where the day temperatures are well above 35C, and humidity high. The increasing electricity cost makes air-condisononing unaffordable to many people, though it is necessary for simple comfort. One of the main reasons why the cost of power is high and still keeps rising is, the way the power is generated and distributed. • The primary cost is the fuel cost and its ever increasing trend • The inefficiency of power generation and distribution • All house hold appliances are made to be compatible with AC power distribution. • Even solar generated power (DC direct current) is converted into AC (alternate current), in order to be compatible with AC grid. The above issues can be easily addressed by following the simple method, outlined below, so that air-conditioning becomes affordable to everyone. We are discussing about various renewable energy source options, particularly about solar energy for air-conditioning in this article. The centralized power plants operate in remote locations with an easy access to fuel source. They generate power from coal, oil or gas and then transmit power through a common grid to various consumers. During this transmission, there is a grid loss up to 10%.First it reaches a sub-station, where the high voltage power such as 11Kv/22kv/33Kv is stepped down to 220V/440V as the case, may be. During this process, there is a loss of power up to 5%. When this low voltage power reaches your home, you have to convert them into DC supply, using AC/ DC converter. For example, you need to use your laptop or PC, you need a converter. During this process, there is again a loss of power up to 5%. The efficiency of power generation by fossil fuels is only about 35%, and the balance 65% is emitted as waste heat in the form of greenhouse gases. The net power efficiency at the point of usage at our home will be only about 25-27%. Only 27% of the heat value of the fuel is converted and supplied, reaches you in the form of electricity. The rising cost of fuel and inefficiencies in generation and distribution, are the major factors for such high cost of power. Imagine, how many decades we have been using this power using the same technology, and paying our bills! One can easily justify why we should switch over to renewable energy source. It makes a great sense of economics and environmental protection! Since we have been using such power distribution systems for so many decades, all the house appliances are manufactured to be compatible, to the power supply. Unfounately, many of our electronic appliances can operate only on DC current. This has forced us to use many converters at our homes, of various specifications, for various uses. That is exactly why we are using a rectifier to convert the solar power, which is a DC current, into Ac current, so that we can use air-conditioners readily available at stores, which are AC power compatible. But this conversion results in power loss of at least 5%. It will be easier and economical to use directly, solar DC power into DC powered Air conditioners. The solar panel should be connected directly to a split air conditioning unit, through a charge controller and battery bank. The power supply to the unit will be 48VDC, connected to the outdoor unit. The compressor used in this air conditioner is DC operated, scroll compressor, which is more efficient and operates smoothly, and it can be connected directly to your solar panel, without using a rectifier. You can also use a small wind turbine to connect to this air-conditioning system. You can even use this system in your caravan, when you are not driving! As a matter of fact, all your house appliances from TV to Vacuum cleaners can be directly connected to your solar panel without any rectifiers.