Just like other medium temperature solar thermal collectors—glazed flat plate and evacuated tube collectors—a Sunplate® has an absorber with fluid passageways inside an enclosure to isolate the absorber from ambient air temperature. So what’s the big idea?
A Sunplate® has no glass.
In fact, a Sunplate® has no transparent or translucent glazing of any kind to transmit solar energy into the solar collector interior. The cover of a Sunplate®—the part of the solar collector that faces the sun and absorbs solar energy—is opaque. It does not transmit light to the solar collector’s interior.
Sunplates® operate by a fundamentally different principle than other medium temperature solar collectors. Rather than transmitting solar energy through transparent or translucent glazing, an opaque cover absorbs solar energy at its exterior surface, which heats the opaque cover, then infrared energy is emitted from the cover’s interior surface to the absorber. Additional heat is also transferred to the absorber through conduction and convection. But unlike current medium temperature solar collectors, the interior surface of the cover plate is designed to be hotter than the absorber during normal operation. This increases energy transfer from the opaque cover to the absorber because infrared energy emittance increases to the fourth power of the temperature of the emitting surface.
Why opaque cover technology is a big deal
Opaque cover technology does not have the failure points of glazed flat plate collectors and evacuated tube collectors, the two legacy technologies that dominate the global solar water heating market today. These failure points, which reduce heat output and shorten collector useful life, are:
- glass breakage
- collector overheating
- loss of thermal insulation
- moisture intrusion
Opaque cover technology is a radical rethinking of the solar water heating collector that eliminates these failure points. The Sunplate solution is simple, elegant and rugged. Manufacturing cost is about the same as mass-produced Chinese evacuated tube collectors, which enjoy the largest global market share but generally last fewer less than 10 years before failure.
Designed to last longer
Sunplate® Opaque Cover Technology was invented by people who have more than 30 years of experience working with thousands of solar collectors. While Sunplates® will cost less to manufacture, they have been designed to be more durable than glazed flat plate and evacuated tube solar collectors. Sunplates® have fewer potential points of failure, so they will deliver designed thermal performance not just during the first few years after installation, but for several decades.
Sunplates® for all seasons
A Sunplate® sacrifices some performance, compared to a glazed flat plate collector, in windy and very cold weather, but this shortcoming is more than offset by the manufacturing cost savings—opaque cover Sunplates® cost about 40% less than glazed flat plate collectors to manufacture. Evacuated Sunplates®—with or without glass—can be used when higher temperatures or very cold weather operation are required.
Learn about how our technology works.