5 February 2012
Solar Hot Water

Solar hot water can be one of the most economical forms of alternative energy. Unlike solar electric panels that convert approximately 15% of the suns energy to a usable form; solar hot water panels collect and retain approximately 80% of the suns energy.

With a solar hot water system installed, the water heater rarely needs to operate during the day. This offsets the electric or propane that would otherwise be used to heat the water and results in a tremendous energy savings.

If you are interested in utilizing solar hot water in your home or business please contact us.

Browse solar hot water panels and accessories in our online store.
Solar Domestic Hot Water Panels
Live System Data! Minimize
To see how a solar hot water system works in action.
Check it out at the Live Monitoring Website.

This system was installed by Aurora Power & Design in January 2011. The system was installed at the Boise City Hall and was designed to closely demo a residential sized system. The detailed monitoring was installed to accurately determine the amount of hot water produced and utilized by the building.
 
How Does Solar Hot Water Work? Minimize
There are two types of solar hot water systems; drain down systems and closed loop systems. Drain-down-systems operate at atmospheric pressure and have an overflow tank. At night when they are not operating they drain back down into the tank. Closed loop systems operate at above atmospheric pressure and use an expansion tank. At night closed loop systems do not drain. Closed loop systems must also be filled with propylene glycol in order to prevent freezing in the winter.

Aurora Power & Design installs closed loop systems in all of our new installations. Closed loop systems can operate at higher temperatures, and are more reliable.

A simplified solar hot water system is shown below.



First solar radiation strikes the panels and heats the working fluid. The hot working fluid is then directed through a double wall heat exchanger where heat is transferred to the domestic hot water. The double wall heat exchanger is often built into the domestic hot water tank for a cost savings. The cool working fluid is then pumped back to panels with a circulating pump.

An expansion tank is added to allow the fluid to expand and contract as it heats and cools. An emergency pop-off valve is also added to prevent the rupture of the plumbing should the expansion tank not be large enough to accommodate the fluid. Aurora Power & Design also adds temperature and pressure gauges to properly configure and monitor the system.
 
How Does Solar Space Heating Work? Minimize
Solar space heating operates the same as a solar hot water system except that the heat energy is used to heat air instead of domestic hot water.

Solar Space Heating system layout
 
Why are solar hot water panels more efficient than solar electric panels? Minimize
Solar hot water panels are more efficient than solar electric panels because their black internal surfaces are able to absorb nearly all frequencies of light. Solar electric panels on the other hand can only absorb a range of frequencies that match the band gap of the semiconductor.
 
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