What is the difference between the two types of Solar panels:
Flat Plate vs. Evacuated Tubes?

Evacuated tube panels are more efficient than flat plate collectors; consequently they take up less space. They are, however, more expensive than flat plate panels. The flat-plate collector is the most commonly used system for homes. It is an insulated, weatherproofed box containing a dark absorber plate covered by one or more transparent or translucent covers. A collector is typically 2’ – 4’ wide, 5’-12’ long and 4” in depth. The absorber plate gathers the sun’s heat energy. This heat energy warms the antifreeze (or water) solution that flows through the attached tubes. Once heated, the liquid is pumped through the tubes to the heat exchanger, located in front of the storage tank. The heated liquid warms the cooler water in the storage tank. This warm water is then transferred into the backup storage tank. When the hot water tank falls below a preset temperature, the backup energy source — such as a natural gas or LP water heater or boiler -- maintains the preferred water temperature.

The evacuated-tube collector is made up of rows of parallel, transparent glass tubes. Each tube consists of a glass outer tube and an inner tube that is covered with a selective coating that absorbs solar energy but inhibits heat loss. The air is evacuated from the space between the tubes, thus forming a vacuum. This tube design eliminates conductive and convective heat loss. Evacuated-tube collectors warm the liquid in the tube more efficiently than flat- plate collectors and they perform well in both direct and diffuse sunlight. Evacuated-tube collectors are best suited for commercial or industrial use and are more expensive than flat-plate collectors.

We represent Heat Transfer Products vacuum tubes and flat panel collectors.