Solar water heater have been used for over 100 years and the 1st set of solar water heater were commercially available in before the 1900’s. These system were basic black tanks placed on top of the roof. The black paint absorbs the sunlight and heats up the water in the tank. The concept today is evolved to a much great level of technology and temperatures reaching 400 F are possible. However the basic principle of solar water heating is the same. The sun’s radiation is absorbed and transferred to the water directly or indirectly through a heating fluid and a heat exchanger’s loop.
Modern day solar heating is now possible in almost any temperature or climate with the introduction of vacuum tube solar water collectors. The vacuum tubes are similar to a thermos and as such loose less than 3% off the heat they capture. This means solar water heaters can provide water heating year round regardless of the outdoor temperature. The evacuated tubes are also able to deliver high temperature water for commercial solar heating and industrial use which has greatly evolved the way solar energy is being used.
In North America most people know solar water heating in the form of solar pool heaters. These black plastic mats sit on the roof of houses and provide free energy for pool owners. However they are limited in their capacity. Modern High Performance solar water heaters can be used to provide both pool heat in the summer and space heating in the winter. The popularity of solar heating has tripled in the last decade with states such as Hawaii mandating solar water heaters on all new home construction.
Traditional Photo Voltaic panels capture about 15% of the solar energy where by modern day solar vacuum tubes can capture 60-80% of the energy. This makes solar thermal much more efficient when heat energy is required such as home heating, domestic hot water and pool and hot tubs.
Solar Thermal energy is also used to create electricity by creating high temperature steam that drives turbines. The largest solar power plant in the world uses solar thermal energy to generate 392 MW of power. The Ivanpah Solar Thermal plant is located in the Mojave Desert uses concentrated mirrors to reflect the sun’s energy to large heating towers providing thermal energy to create supper steam to drive the turbines.
A major advantage of solar thermal energy is that it can be easily stored for use as needed. This is done by using highly insulated solar hot water tanks to store the energy. The energy can then be pulled out during the evenings or as needed. Unlike solar PV there are no costly batteries, charge controllers or inverters that that are needed, just a simple solar water tank is all that is used.
For homeowners and commercial businesses that want to save money and invest in Green Energy, solar thermal water heater systems are more practical to provide direct heat energy than using Photo Voltaic energy to create heat. A home owner can buy a simple solar domestic hot water heater for as little as $3000. The investment also is eligible for tax incentives that in some states in the US can be as high as 80% of the cost. This make solar water heating an ideal investment with great returns for residential and commercial heating applications.
One of the 1st solar commercial water comapanies