solar hot water systems

Residential Solar Thermal System

Typical Residential Solar Thermal System (click to enlarge)

The Time Is Right for Solar! Arguments against solar panels have focused on prohibitive costs, but current federal, state and local utility incentives have made this the best time to go solar.

Have you ever felt warm water trickle out of a garden hose that’s been sitting in the sun? If so, then you’ve witnessed solar water heating in action.

Now imagine that same water moving slowly though a system specifically designed to heat and store water – that is the essence of solar thermal water heating. People have for centuries used water heated by the sun and stored it for bathing, hand washing, cleaning clothes, heating homes and much more. The solar thermal systems used today combine the most efficient techniques for capturing the sun’s heat with modern plumbing systems to produce cost effective hot water and reduce the need for gas or electricity to heat water.

There are a number of different solar thermal designs, but all are based on the same simple principle as the garden hose.  Each has its pros and cons, and each is suitable for a specific application.  Consult with your local installer to determine which is best for your situation.

Solar thermal energy (STE) is a technology for harnessing solar energy for thermal energy (heat). Solar thermal collectors are defined by the USA Energy Information Administration as low-, medium-, or high-temperature collectors. Low temperature collectors are flat plates generally used to heat swimming pools. Medium-temperature collectors are also usually flat plates but are used for creating hot water for residential and commercial use. High temperature collectors concentrate sunlight using mirrors or lenses and are generally used for electric power production. STE is different from photovoltaic, which convert solar energy directly into electricity. While only 600 megawatts of solar thermal power is up and running worldwide in October 2009 according to Dr David Mills of Ausra, another 400 megawatts is under construction and there are 14,000 megawatts of serious concentrating solar thermal (CST) projects being developed.

The panels we distribute are Medium Temperature collectors.  These collectors could be used to produce approximately 50% or more of the hot water needed for residential and commercial use in the United States.  In the United States, a typical system costs $5000–$9000 and 30% of the system qualifies for a federal tax credit + additional state credit exist in about half of the states. With this incentive, the payback time for a typical household is four to nine years, depending on the state. Similar subsidies exist in parts of Europe. A crew of one solar plumber and two assistants with minimal training can install a system per day. Thermosiphon installation have negligible maintenance costs (costs rise if antifreeze and mains power are used for circulation) and in the US reduces a households’ operating costs by $6 per person per month. Solar water heating can reduce CO2 emissions by 1 ton/year (if replacing natural gas for hot water heating) or 3 ton/year (if replacing electric hot water heating). Medium-temperature installations can use any of several designs: common designs are pressurized glycol, drain back, batch systems and newer low pressure freeze tolerant systems using polymer pipes containing water with photovoltaic pumping.