A solar thermal system collects solar energy using vacuum tube collectors, transfers the heat to a storage tank, and uses a controller to regulate backup heat sources. The tube collectors absorb UV rays, trapping the heat inside glass tubes surrounded by a vacuum. This heat is transferred to a glycol mixture and then to a storage tank for later use in heating buildings or water. A controller monitors temperatures and operates pumps and boilers as needed to provide heat day and night.

2. Thermal Solar Collector Solar Thermal Technology is made of a tube collector, collection tank, controller panel and usually a boiler and/or heat pump. The tube collector is a vacuum tube that absorbs the UV light and turns it into heat The following is some information on these items. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

3. The Collector The collectors on a system is almost like the leaves on a plant. It is pointed toward where it will gain the most exposure from the sun and is collecting the solar radiation to create the thermal heat. The figure above gives the process of how this transformation from solar energy to thermal energy happens. The glass tubes of the collector is made up of two tubes. The outside tube is clear while the inside tube is black. In between the two tubes is a vacuum. The black tube attracts the UV rays that are carrying the solar energy. Since it is energy, it can easily pass through the vacuum. Once the UV hits the black tube, that is when the solar energy is transformed into solar thermal heat. Heat cannot travel through a vacuum, so it is trapped inside the tube. The temperature inside the tube continues to build up and is conducted up the copper pipe to the manifold. Inside the manifold of the collector, this heat is transferred to a glycol mixture that is then taken to the storage tank. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

4. If there was a heart to the solar system, this tank would be it. The hot mixture from the collectors is pulled into this tank and passed through a heat exchanger. The heat is transferred from the hot mixture in the heat exchanger and into the water in the storage tank. That water can then be sent through a radiant floor system, a water coil, or a hot water heater for domestic hot water heat. The second heat exchanger is where a flash boiler would be hooked into for backup heat. The figure gives a cutaway of the tank and lists its parts. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

5. The Controller If the storage tank was the heart, the controller (See Figure 1-4) is the brains. This device is what communicates to the system to tell it when to shut the primary solar system off and rely on the backup system until the solar system can get back up to temperature. This device is connected with sensors in the tank and collectors. It knows at all times what the temperatures are and when to start and stop the pumps. Most generally, a solar system will need a backup device for times that the collector can’t meet its full load of heat due to very cloudy weather or at night when there is no sunlight at all. Because of this occurrence, for most installs that have gas available, a 95% efficient, modulating, wall-mounted boiler is used. For conventional, forced-air systems, a heat pump also might be added. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

6. FAQ QUESTION: Can solar energy save you money? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

7. FAQ ANSWER: Yes! There is typically around a 3-6 year payback period for most types of heating applications. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

8. FAQ QUESTION: Can solar work during cold weather? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

9. FAQ ANSWER: Yes! Unlike older flat collectors, the vacuum in the tube collectors trap the heat and allow it to be unaffected by extreme cold temperatures. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

10. FAQ QUESTION: What is the life expectancy of a solar thermal system? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

11. FAQ ANSWER: To be honest, no one knows the life expectancy on this system. We do know, however, that these systems have been installed in other countries for over 20 years now. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

12. FAQ QUESTION: What is the difference between the tube collectors and the flat collectors? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

13. FAQ ANSWER: Both types of collectors will efficiently create the thermal energy. The tubes is more of a “well rounded” collector because where the flat panel has no vacuum and will los e heat in the wintertime, the tubes will not. Another nice thing about the tubes is, because they are round, they can pick up the maximum solar rays when the sun is at any position in the sky. The flat panel is capable of only picking up the max solar rays when the sun is directly above it. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

14. FAQ QUESTION: Is there any maintenance to a solar system? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

15. FAQ ANSWER: Not really. The only thing that really needs to be done is to make sure that the bulbs are clean. If there is any dirt, dust, or any other residue that is on the bulbs, it will take away from the efficiency of the collector. Just get a hose and spray down and then wipe away any of the buildup on the bulbs. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

16. FAQ QUESTION: What kind of temperature can a solar system produce? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

17. FAQ ANSWER: Currently, we have seen temperatures reach up to 380° F. This is not the maximum temperature that it can perform, it is the max that we allow it to reach because it will start to boil our mixture if we don’t. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

18. FAQ QUESTION: If the bulbs are made of glass, wouldn’t they break easily? Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

19. FAQ ANSWER: With glass, there is strength in a circle. There have been many tests performed on these glass tubes and it has been determined that it can withstand up to a hail ball at the size of 1-1/4”. That size would be about the size of golf balls. Courtesy of SolarAg Systems 1001 N Wayne St. Portland, IN 47371

20. Solar Tube Strength Test