Have you ever heard of solar thermal energy (STE) but weren’t exactly sure what the person was talking about?! STE is a highly efficient technology created to capture solar energy from the sun’s heat which is then used to run a heat engine which generates electricity. STE is not the same as photovoltaic (PV) energy or solar panels which capture solar energy through the sun’s light and heat turning it directly into electricity. Collectors of STE can be classified as low-, medium, or high temperature collectors. These solar collectors are also commonly known as solar hot water panels.
To read more about PV energy please see “What is Solar Energy”
As mentioned above there are three types of STE collectors: low-, medium-, and high-temperature collectors. Why are there three different types? Each type of STE collector is used to heat items in a slightly different manner. Low-temperature collectors are designed as a flat plate and are commonly used to heat swimming pools (solar pool heater). Medium-temperature collectors are also designed as a flat plate and are commonly used to heat water or air that is used by both commercial and residential consumers. High-temperature collectors concentrate the sunlight by using lenses and mirrors and are commonly used for the production of electrical power.
Solar Thermal vs. Photovoltaic (PV)
In “What is Solar Energy“ we discussed how PV energy/solar panels work. STE however captures the sunlight as heat using it to run a heat engine by heating a substance. Engine types used in STE include: stirling engines, steam engines, gas turbines, and many more. Meaning that substance could be either a liquid or a gas such as water, oil, nitrogen, helium, salts, air, etc. This also means that some STE collectors have the ability to freeze during the cooler months or boil during the warmer months, possibly destroying the whole system.
Over the past years STE efficiency has been seen and known to outweigh that of PV energy or electric energy when it came to heating water. Seeing as STE collectors have the ability to capture more energy, this was one that could not be competed with. However, with the decreasing prices of PV panels over the past six years also came the trend of air-to-water heat pump technology. Together this technology and PV energy have provided consumers with solar-electric assisted heat pump water heating (HPWH). With HPWH there is better performance as the solar collector is coupled with the refrigeration cycle which allows the refrigerant to expand inside the evaporator allowing it to absorb solar energy.
Solar Water Heating
Solar pool heater
Solar pool heaters or heating is the most cost-effective form of solar energy in many climates. Like other solar energy systems there is a start up fee but is cost effective when thinking in the future. With little annual costs for operating solar pool heaters, they are idea when compared to electric and/or gas heaters. Along with swimming pools (or lily ponds) many people like to add fountains as a feature to enhance the pools appearance. Solar powered pool fountains are also environmental friendly, plus there is no electric bill! Most solar powered water features (i.e. fountains) come ready-to-use, only requiring you to fill the product and place it in the sunlight. They also help keep the algae out of your swimming pool! Aside from the ready-to-use solar power features; there are also features which come with a separate solar panel that is connected to a pump. This panel is situated in a nearby location allowing it to receive energy to perform its duties.
Solar Roof Heating
Like solar thermal water heating, roof heating heats a tank of water which is used to then provide your home and/or property with hot water. During the winter months many may worry about the amount of energy being produced, but STE panels will provide enough energy in order to pre-heat your tanks sequentially helping you save on your energy bill. How do these panels work? Like solar panels STE collectors are fitted to your roof, the collectors absorb or collect the sun’s heat, heating up the water in the panels. The panels then release the water through your hot water cylinder coils heating up the water in the tank. Hence the amount of hot water you are provided with.
Since hot water is generated from the sunlight, you will have hot water year round and for many of years to come. Possibly with different outputs during the cooler, darker months but STE collectors will still be more cost effective in the long run. STE systems are said to save you between 50 and 75% of your hot water bills. These systems also require very little maintenance, making them ideal to those who want to save on hot water!