Solar Flywheel System

Goals of Innovation: Use low temperature solar heated fluid during the winter to significantly contribute to the home's heating requirement.

Description: This area of Vermont has approximately 8,000 Heating Degree Days. The winter sun is not intense and the days are short. Yet, it was determined a solar heating system could supply significant BTUs to the home.

By supplementing the 95% efficient Polaris propane water heater, the sun provides more than 75% of this home's total heat and domestic hot water. The combination of active solar collection and passive distribution provides for all but the highest hot water demands in the summer. Although the winter sun is too weak to heat the domestic hot water, it supplies a boost to the heating system.

Coming directly from the ground mounted solar panels, 75 degree fluid (antifreeze) circulates through radiant tubing to the 120 gallon water storage tank (with integral heat exchanger), as well as to 16 inches of sand leveled between the foundation's ICFs and beneath the slab containing the radiant heat tubes heated by the propane water heater. The combined thermal mass of the sand and slab makes the home feel, as builder Al Rossetto says, "As if the home is sitting on a beach in the Caribbean."

Obstacles: Radiantec designed and engineered the system and encountered no problems. It was key to understand the solar heating potentials and assure the system was designed according to home heating needs and component capacities. It is important that the homeowner check the gauages periodically to assure the system is functioning properly. This is true for any system, however.

Cost Information: The solar system was built into the home, not added on, so the cost was in line with a ﾓstandardﾔ heating system.

Additional Benefits/Drawbacks: The system works better than expected. By supplementing an efficient gas water heater, the sun provides more than 75% of the home's total heat and domestic hot water. The combined average monthly bill for heating and water heating is approximately $40.