Solar Concentrators have the task of converting light into a focused area on a collector that measures 10" x 10" in size. Solar concentrators are best used in application that need a lot of solar hot water heating . Solar concentrators consist of a parabolic dish that reflect light onto a small collector. This is similar to the concept of using a magnifying glass to focus light on a small area. When high temperatures are focused on a small area, the water can be heated very fast and can be used for solar heating . The collector is usually dark coated and has special properties that absorb 97% of the light waves. Inside the collector is an absorber. Inside the absorber is a system of pipes that is filled with a heat transfer medium (usually water with anti-freeze properties). The water is heated by the concentrated light and is then fed to the hot water tanks. A heat exchanger is installed in the building and is used to separate the cool water from the hot water. The cool water flows via a second pipeline back to the collector while the heated water goes to the hot water tanks. The heat exchanger come in sizes as small as a piece of paper to as large as garbage dumpster. In most cases though, one heat exchanger can be connected to 3 SolarBeam Concentrators if the required flow rate of solar hot water is 4 gallons/ minute. If a higher flow rate is required then a larger heat exchanger will need to be purchased.
The best solar hot water heating are the ones that achieve efficiencies of 85% at when heating water to 90 degrees Celsius. SolarBeam uses a proprietary material for its collector to ensure high light absorption capacity and low thermal emissivity. Most spectral-selective layers have an absorption rate of 90%-95%, and an emission rate of 5-15%.
The efficiency is influenced by the design of the collector: more specifically, it is influenced by the particular optical and thermal losses. The optical losses describe the proportion of the solar irradiance that cannot be absorbed by the absorber. In the case of solar concentrators, the shape of the parabolic curve is critical to ensure that all light is reflected on the 10" x 10" collector. If the shape is not perfect then efficiency decreases because some of the lights is reflected on areas outside of the collector. Also thermal losses are dependent on the temperature difference between the absorber and the outside air, on the insolation and on the construction of the collector. In the case of flat panels, as the difference between the absorber and outside air increases, the heat losses increase and efficiency reduces. Solar concentrators have the advantage that they do not lose efficiencies even when ambient temperatures are drastically different.
To store the hot water you can use unvented tanks that are offered in stainless steel, enameled or plastic coated steel or copper. Stainless steel is more sensitive to water with a high chloride content. Enameled tanks must be equipped with a magnesium or external galvanic anode for corrosion protection purposes. The best storage tanks are the ones made from copper. The advantages of copper are its lightness and the ease of fabricated it in different sizes.