Our south-facing roof is where the sun does its work. There are two areas side-by-side: solar thermal for hot water/heating and photovoltaic for electricity.
Solar thermal: The water
that is circulated in the roof is stored in two 500-gallon tanks in
the basement. When the temperature on the roof is 10 degrees higher
than the water stored in the tanks, pumps circulate the stored water
to the roof to be heated. The pumps shut down when both temperatures
are equal. Even during periods of high thin clouds the system will work, though not as efficiently. The diagram on the right is from industry guru Michael Potts.
Two pumps are required to raise the water from the basement to the
top of the roof. One of them turns off after the natural siphoning
process takes over. A visual indicator registers how much water is
being circulated in the system--great fun to watch.
Here is one of our
two "megatanks" used to store the solar-heated water. My wife Debbi
quickly embraced the idea as well as the tank. We are now harvesting
the sun's energy to keep the interior warm. This is a significant
milestone in our lives--a goal finally achieved after 25 years of
dreaming and planning.
The radiant tubing in the floors was covered with 1 1/2 " of light concrete, then layered with oak. The floors are pleasantly warm to the feet and the heat is evenly distributed throughout the house...slowly rising, naturally.
During the coldest days of winter, the sun seems to shine with unusual brilliance. While neighbors worry about a rising heating bill (we know the feeling having once lived in an electric-heated house), we can accept the sun's gift without any state or federal taxes.
The solar-heated water also provides the basis of our hot tap water as well as circulating through the radiant tubing in the first and second floors of the house. Propane provides any necessary backup as well as gas for cooking and clothes drying.
The mastermind behind the design of the solar radiant heating system is Eric Olsen of EarthStar Energy Systems. He recently revisited our home to "tweak" the technology. What a masterful system it is, now that we've received his thorough and simple explanation of how it all works!
Eric has started an Institute for Biodynamic Shelter in Waldoboro, ME 04572 (207 832-5157). He has written a powerful mission statement.
Email Eric Olsen