"GreenSky Energetics listened to our needs and was the first and only installer to propose a system to benefit both the brewery and the restaurant."
B. Danke - Wausau, WI |
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Solar Water Heating Technology
Understanding Solar Heating |
The basic solar domestic water heating system uses solar energy to preheat domestic water in a solar storage tank before it enters a conventional water heater. On good sunny production days, the water temperature can equal or even exceed what your water heater provides and your water heater will not turn on! Even on partly sunny days the system will increase the temperature of the water in the storage tank. On these days with the water already warmed, your water heater uses less energy to get the water up to temperature. On poor solar heating days, the water heater acts as a back-up system and heats the domestic water to its set point temperature. In a residential application, the system is designed with the number of panels and amount of storage to supply about one day’s worth of hot water. The system can be expanded to capture more heat from the sun and store in the tank. Once we have the heat in the tank, we can put it to work where we need it, for example to supplement your home heating system. This basic approach can be scaled up by increasing the number of collectors and solar storage capacity to fit the needs of commercial businesses ranging from restaurants to office building to breweries.
System Configurations
There are two basic configurations of solar water heaters: pressurized and drainback. The pressurized system always has solar fluid in the collectors. When the collectors get hot, the fluid is pumped to carry the heat to the storage tank. When the pump stops, the fluid remains in the collector and is subject to the seasonal weather conditions of heating and freezing. These systems provide good functionality when the day-to-day need for hot water is fairly constant. The solar fluid in a drainback system will drain back out of the collectors into a tank inside the building when the pump stops. This capability protects the solar fluid during long durations of the pump not running. The drainback style is best suited for applications with a variable day-to-day need for hot water. Which system configuration is best? One of the distinctions of GreenSky is that we take time to meet with you and understand your specific needs and situation. We do not have cookie cutter systems but will develop a system tailored to you.
Theory of Operation
Let’s look at how a typical drainback system works. The solar domestic water heating system is divided into two subsystems:
1) Solar loop
2) Domestic water.
Refer to the simplified diagram below showing the system’s basic components. The solar loop subsystem consists of solar thermal collectors, a pump, and a heat exchanger embedded in the solar storage tank. The domestic water subsystem consists of a solar storage tank filled with domestic water from the city supply, a traditional water heater, and a thermostatic mixing valve. Each sub-system is a closed loop system and prevents intermingling of the fluids.
The solar collectors capture heat from the sun. When the collectors reach a temperature higher than the water in the solar storage tank, the solar loop pump is turned on. The solar loop pump pumps fluid from the drainback tank to the collectors. The fluid is heated as it passes through the collectors. The heated fluid exits the collectors and flows through the drainback tank to the heat exchanger in the solar storage tank. The heat exchanger allows the fluid to give up its heat to the water in the tank. The cooler fluid returns to the pump and the cycle continues. The water in the storage tank can be heated by the solar loop to temperatures as high as 160F°. Opening a faucet draws hot water from the water heater and pressure from the city water forces preheated water from the storage tank into the water heater. (Colder city water is also introduced into the bottom of the solar storage tank.) Introducing this preheated water to the water heater eliminates or reduces the energy demanded by the water heater. The thermostatic mixing valve tempers the outgoing water temperature by introducing cold water when the preheated water exceeds 120F°.
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Related GreenSky Energetics Projects...
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One System, Multiple Homes | Bonduel, Wisconsin |
| This specially designed pressurized closed-loop solar domestic water heating system services two houses. The solar collectors are mounted on the garage roof of the apartment, situated less than 25 feet from the main house. The solar loop travels down... Cont'd here... |
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Red Eye Brewery and Pub | Wausau, Wisconsin |
| The solar water heating system on the Red Eye Brewery in Wausau is a terrific example of the positive impact from investing in renewable energy. The owners wanted to incorporate renewable energy into their facility as part of their mission statement:... Cont'd here... |
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Awning Mount | Combined Locks, Wisconsin |
| Here is one of our more creative collector mountings. Since the home has an east / west roof. the traditional roof mounting of the collectors wouldn't work. Using the generous amount of wall available on the southern wall, we were able to do an... Cont'd here... |
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Outagamie County Regional Airport | Appleton, Wisconsin |
| A twelve collector drain back system preheats 600 gallons of domestic water for the airport. The collectors are arranged as two arrays of six collectors. There are five storage tanks with internal, double-wall heat exchangers. A recirculation line di... Cont'd here... |
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