The Affordable Solar Project (ASP) is seeking to make efficient, easy-to-install solar water heaters that are affordable enough to make them a real option for the majority of the population
The heaters consist of vacuum tubes that track the sun across the sky contained within a unit that can be mounted on either angled or flat surfaces. The tubes direct the sun’s radiation to an internal heat pipe which acts as a solar energy absorber. The solar energy is then transferred to a workable vapourizable fluid which rapidly rises to a condenser at the top of the heat pipe. This transfer the heat to water in the tank. As the heat is lost, the vapour condenses into a liquid and returns to the bottom of the heat pipe and the cycle starts all over again.
The unit incorporates a pressurized system which ensures strong water flow and refills automatically. Since there is no water inside the tubes, there is no danger of freezing and because each tube is a self-contained loop if one of them breaks the rest of the unit can continue to operate efficiently. The heaters don’t require a controller, circulation pump or a feeder tank and have been designed to be cheaper and easier to install than separated collector and tank units. They can heat water in all climates, even in below-freezing ambient temperatures and an insulated tank retains collected heat for up to 72 hours. The plug-and-play design ensures immediate production of piped hot water from the sun.
According to ASP, evacuated tube collectors are far better than conventional flat plate collectors as the tubes are hermetically sealed within an evacuated glass tube which eliminates convection and conduction heat losses and isolates the tube from adverse ambient conditions. The collectors use a heat pipe for super-efficient heat conduction whereas flat plate collectors circulate water within insulated areas and are prone to leakage, corrosion and restriction of flow due to air lock.
Averaging over a year, the group maintains that a correctly sized solar system should be able to provide 60 to 70 percent of a households hot water needs. ASP have also just changed their tentative pricing schedule in order to make the larger units more affordable.
“The goal is to provide the best units possible at a price cheaper than or comparable to conventionally fuelled water heaters” Randy Martin said. “Units would come in a range from those suited for 2 people, which would cost only $550 (Before the Federal 30% tax credit, which would bring the unit's cost down to $350) all the way up to units suited for a family of 7, which would cost only $1100 ($770 with the Federal Credit).”
ASP’s solar water heaters should not cost too much more than a new electric or gas system. Although the collectors are visible on the roof, they have been designed to blend in with the roof quite easily. They can also be fitted on a flat roof or on the ground through the use of a mounting frame which should be installed at a 20 degree angle to ensure optimal heat pipe operation.
At present ASP is seeking public funding in order to go into full production. They are also giving away solar electric setups in return for funding contributions.