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| − | '''Bulbs''' have an efficiency of only 5%. '''Halogen lamps '''are only slightly more efficient. They are, therefore, not suitable for solar systems. '''Fluorescent lamps''' of the tube or compact type are 5 times more efficient and can last 5,000 hours and more. They need a good and efficient electronic ballast for operation. Fluorescent lamps with electronic ballasts cost about 10 € for [[Alternating_current|alternating current]] (AC) and 20 € for direct current (DC) (prices as of 2002). | + | '''Bulbs''' have an efficiency of only 5%. '''Halogen lamps '''are only slightly more efficient. They are, therefore, not suitable for solar systems. '''Fluorescent lamps''' of the tube or compact type are 5 times more efficient and can last 5,000 hours and more. They need a good and efficient electronic ballast for operation. Fluorescent lamps with electronic ballasts cost about 10 € for [[Alternating current|alternating current]] (AC) and 20 € for direct current (DC) (prices as of 2002). |
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Revision as of 14:11, 27 July 2009
Lamps
Bulbs have an efficiency of only 5%. Halogen lamps are only slightly more efficient. They are, therefore, not suitable for solar systems. Fluorescent lamps of the tube or compact type are 5 times more efficient and can last 5,000 hours and more. They need a good and efficient electronic ballast for operation. Fluorescent lamps with electronic ballasts cost about 10 € for alternating current (AC) and 20 € for direct current (DC) (prices as of 2002).
Audio and video devices
Most appliances such as TVs, receivers or video recorders operate on AC. There are a few exceptions including some DC TVs. Color TVs consume more than black & white ones. There are considerable differences between individual brands. TVs should not be operated in stand-by. Controllers and inverters may disturb operation of TVs and radios.
| Power demand of color TVs
|
| Size
|
Power
|
| 17 cm
|
20 W
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| 25 cm
|
40 W
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| 37 cm
|
60 W
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Transistor radios and cassette players are operated by batteries at a voltage below 12 V. Since batteries are expensive, such appliances should also be connected to the solar system through a voltage converter.
Water pumps
Some tens of thousands of pumps powered by solar generators are currently in use worldwide. A variety of pumps for low water demand are available on the market. These include single-stage centrifugal pumps for lifting heads < 10m and diaphragm pumps for larger heads, both DC- and AC-operated. They are surfacemounted, floating or submerged pumps. DC pumps with brushes need regular replacements.
The energy requirement (E) for a daily water demand (Q), a pumping head (h, water level to tank inlet or pipe outlet) and a pump efficiency (η = 0.2-0.4, depending on type and pumping head) is
E [kWh] = h [m] x Q [m³/d] / 367 / η
Refrigerators
Refrigerators are available for AC and DC. DC refrigerators are more expensive. They cost more than 600 €. The size has only a small effect on the price. Only low-consumption refrigerators of the compressor type are suitable for solar systems. A 100 l high-quality refrigerator without an icebox may consume approximately 300 Wh at 24°C and 450 Wh at 32°C. Ice production, a high demand for cold drinks and a low-efficiency type can easily double or triple this figure. Box types are more efficient. Special types are available for vaccine storage. Starting at low voltage levels (<11.5 V) is a problem for many refrigerators.
Source: Klaus Haars, GATE-ID technical brief: Electricity from Sunlight, Solar Energy Supply for Homes and Buildings, Eschborn, 2002.
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