FLAT PLATE SOLAR HOT WATER SYSTEM
A Flat Plate Collector is a heat exchanger that converts the radiant solar energy from the sun into heat energy using the well-known greenhouse effect.
For most residential and small commercial hot water applications, the solar flat plate collector tends to be more cost effective due to their simple design, low cost, and relatively easier installation compared to other forms of hot water heating systems. Also, solar flat plate collectors are more than capable of delivering the necessary quantity of hot water at the required temperature.
A solar flat plate collector typically consists of a large heat absorbing plate, usually a large sheet of copper or aluminium as they are both good conductors of heat, which is painted or chemically etched black to absorb as much solar radiation as possible for maximum efficiency. This blackened heat absorbing surface has several parallel copper pipes or tubes called risers, running length ways across the plate which contain the heat transfer fluid, typically water.
EVACUATED TUBE SOLAR HOT WATER SYSTEM
Evacuated Tube Collectors collect the heat through a number of annealed glass tubes that each have their own heat-absorbing plate inside. There are loads of different designs, but the basic principle is the same for all designs.
Basically each tube is like a little greenhouse that traps sunlight inside the glass tube which is used to heat either the water directly, or a special heat transfer fluid that transfers the heat to the water.
This system used for solar air conditioning, heating or commercial process. Evacuated tube heat pipe collectors can more easily attain the higher temperatures needed, they can collect and retain heat even when it is very cold outside.