To convert the sun’s radiant energy into heat energy is the key in solar energy heat utilization. Because solar energy is scattered, it’s important to put it together to use with the solar water heater system. So the solar collector is a key part of the various devices of solar energy utilization and flat plate solar collector is commonly used in solar water heater, etc. China solar collector predominated in the market in the 1980s but gradually slipped to about 12% now. There are many factors:
1) Direct system flat plate solar water heater can’t be used in winter and is complex for maintenance because of its freezing and having to be empty in winter.
2) All-glass vacuum tube water heater can be used throughout the year in most regions.
3) Due to technological innovation, the price of all-glass vacuum tube greatly reduced and the rapid increase of production enterprises promote the solar water heater market is expanding fast.
The domestic market pattern of the current household water heater, therefore, is due to factors such as the characteristics of the product and price, etc. It is predictable that all-glass vacuum tube water heater will still occupy a leading position in household water heater in low block market. Foreign market has always given priority to flat panel solar collector because of different design concept in the wonderful solar water heater system . Foreign systems usually adopt indirect system, separation system and closing pressurized system. These systems have high initial investment generally, but the system is reliable, not polluted and has low maintenance cost and long life. For such systems, flat plate solar collector reflects its own technological advantages:
1) It is mostly suitable for pressurized system and dual cycle solar water heater.
2) It’s conducive to combine the solar water heater and architecture.
3) The system works long life and needs low maintenance cost.
4) In most case, it can provide more living hot water.
5) Flat plate solar collector for solar energy heating system can be convenient to solve the overheating problem of the system.
Therefore, in the solar system engineering and split type solar water heater, flat plate solar collector has obvious advantages than all-glass vacuum tube collectors in the system life, maintenance, etc. Against the gap between domestic and foreign flat plate solar collector, the following measures should be taken to improve the quality and performance of china solar collector:
1) Research and development is suitable for flat solar collector selective coating which should have high absorption rate, low infrared emissivity, excellent heat resistance and processing cost.
2) Flat plate solar collector should be made by low iron high transmittance glass plate. There are multiple manufacturers which have begun to produce a low iron glass applying to solar collector which decreases the quality gap between home and abroad.
3) Pay attention to the optimal design of the collector, improve the manufacturing process, ensure the stringency of the structure and reduce the heat collector loss.
4) Toughened glass is chosen as the collector plate to improve the quality of collector components. Optimize the structure design to ensure that the collector can withstand hail, wet in the rain, air drying, pressure and thermal shock performance test. Improve working time of the collector and reduce system maintenance cost.
5) In order to adapt to the cold regions, solar heating and air conditioning as well as special requirements such as industrial heating should develop the most efficient flat plate solar collector. Make double flat and transparent honeycomb technology industrialization as soon as possible to increase its cost performance and making efficient flat plate solar collector has the strong market competitiveness.
6) Track advanced foreign technology and craft of plate collector, develop new solar collector system and improve the plate collector market share.