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1. In the Beginning
Since the beginning of time humans have been using solar energy, mainly to dehydrate
things: clothes, food and to make salt from the sea and salty lakes.
Nonetheless, it was only as late as the last millennium that the first commercially produced solar heater was invented and patented (US Patent # 4,084,578 ) in March 18, 1976 by Mr.Toshihiro Ishibashi of Kosai, Japan.
This first generation heater was a single valve flat plate metal encased in glass panel connected to an insulated water tank, thermosiphon water heater.
Given this is the first generation solar water heater, inherent weaknesses as expected, are a plenty: mainly its single valve, one cold in and one hot out bottleneck weakness.
This inherent weakness meant that solar water heaters are only feasible where sunshine is plentiful all year round and the need to incorporate an electrical immersion water heater as a back-up heater.
Also, since this is a pressurized system, the system is susceptible to leakages and worse, tank explosion should the pressure release valve fail to work.
In conclusion, the First Generation Flat Plate Single Valve Thermosiphon Solar Heater, though still produced and sold today (royalty free) is both ineffective therefore costly.
2. Evacuated Glass Tube Heater Tubes
In March 19, 1985, Mr. Billy Hunter; Billy of California, USA invented and
patented (US Patent # 4,505,261 ) his metal heater tubes filled with a low boiling
point liquid encased in evacuated glass tubes. His indirect heating system although
effective even in temperate countries are however costly and complicated.
High maintenance cost is needed and not being thermosiphonic in design, water pumps need to be installed to pump the hot water away from the heat exchanger.
3. Malaysia's Teoh Siang Teik "Microsolar"
On January 18, 2000, Mr Teoh Siang Teik, a Malaysian patented his Tubular
Multi-valve Direct Injection Infra-red Solar Heater (US Patent # 6,014,968).
This 3rd Generation thermosiphon water heater's novelty is in it 16 inner cold water tubes in 16 outer heating tubes that delivers hotter and higher volumes of heated water panel for panel, dollar for dollar.
This breakthrough in solar water heating solves all the inherent weaknesses of Mr. Ishibashi's 1st Generation Solar Water Heater without the cost and maintenance penalty of Hunter's 2nd Generation's Vacuum Heating Tube Indirect Solar Water Heating System.
4. China's Tsinghua University by professor Yin Zhiqiang
In the late 1980's, Professor Yin Zhiqiang of China's Tsinghua University
invented the all glass "Evacuated-Tube Solar Collector" (ETSC), China
invention patent 851001424.
The all-glass evacuated collector tubes, because it is made of an abundance element: silica-glass, became an instant success due to their high efficiency-low cost, low heat losses and long life span.
The heat loss coefficient of the water heater is less than 1.0 (Wm-20C-1), the solar water heater is able to utilize all the year round in cold climate. The tube's typical stagnation temperature is 200°C, Solar absorptance (AM1.5) is 0.93, Emittance (80°C) 0.06 and Heat loss coefficient <0.85W/(m2°C)
But it was not until the turn of the New Millennium that this 4th Generation ETSC Solar Water Heater was perfected for commercial sales and exports.
However, the novelty in the 4th Generation ETSC heater is that, unlike Mr. Teoh's invention, it does not depend on any inner cold water tube, but rely on "laminar flow" i.e. stratified flow of lighter hot water on colder water within the tube into the insulated solar water heater tank via thermosiphonic dynamics.
The All Glass ETSC Multivalve Direct Injection Solar Water Heater though simple in design and cheap to produce is indisputably, the Most Cost Effective Solar Heater in the World and is suitable for all climates, especially in temperate countries where freezing can cause water pipe burst, the ETSC robust double walled vacuum borosilicate glass tubes can withstand even the coldest winter condition.
At Solarwyse, we are pleased
to present to you the world's most cost effective solar water heater.