“In the past couple years, we have seen a significant growth in consumer interest for solar water heating systems; however, with the economy, we’re finding people are delaying such large purchases,” said Bernard Kea, president of SunEnergy Hawaii. “The good news about our product is that it is about half the cost of a traditional system, yet it still provides the savings benefits on their electricity bills.”
Before incentives, the cost of a single residential SunCache unit is $2,750. Installation costs start at $450 up to $750 depending on installation complexity. Unlike conventional solar water heating systems, said the company, the passive system does not require pumps, sensors, or controllers, which means maintenance costs are minimal and the system has less chance to malfunction.
The SunCache system pre-heats cold water before it enters a conventional water heater. When a hot-water tap is turned on, cold water from the supply line flows through a copper heat exchanger embedded in the SunCache panel, extracting heat from the unit. The rotationally molded polyethylene panel contains 50 gallons of water, which collects and stores solar energy. A glazing over the panel reduces convective heat loss and helps the panel to hold heat through the night. The amount of heat that the system adds to cold water depends on weather, time of day, season, and recent hot water usage. Because the water heater maintains the desired temperature set point, occupant comfort is maintained.
“By extensively using plastic material we were able to reduce copper and aluminum content and keep system prices low,” said Eric Lee, president of Harpiris Energy and senior engineer in creating the SunCache system. “We have had a lot of success with the product in California and we’re really excited about the benefits it will bring to Hawaii.” SunCache is said to utilize technology that is the result of a nine-year, $2-million R&D program supported by the U.S. Department of Energy and the National Renewable Energy Laboratory.