Tuesday, August 04, 2009
What Kinds Of Hot Water Solar Collectors Can You Build Yourself?
There are 3 main types of hot water solar collectors commonly used in homes: flat plate and
evacuated tube systems. There are a number of different "recipes" for building each kind. But here
is a quick description of their similarities and differences.
First, there are pool solar collectors. These are usually a type of flat plate design, but there
are enough differences between solar pool heating systems and solar hot water heating systems that
some explanation is necessary.
Pool solar collectors, are usually designed as rows of UV resistant black polypropylene pipe that
is heat welded together. Because pool heaters require lower water temperatures than hot water for
showers or for heating a house, the collectors do not need to be encased in a box. In fact, the
polypropylene plastic is not intended to withstand the high temperatures needed for other domestic
hot water use, and should not be enclosed by glass.
Although solar pool heating systems are about the simplest solar energy system that you can build
or install, the solar collectors themselves are not so easy to make. The polypropylene pipe does
not respond to adhesives, and the process and equipment needed for heat welding is cost prohibitive
for a do-it-yourself project. And using a substitute material may not be wise because of its
tendency to break down with ongoing exposure to the sun and chlorine from the pool. For this
reason, it is probably easier to buy the solar collectors even if you choose to install the system
yourself.
Evacuated tube solar collectors are also tricky to build. Although they are used for domestic hot
water and for heating a home with hot water, the materials require special handling. They use
special glass tubing with double walls. The air trapped between the walls act as insulation,
similar to the way dual pane windows trap air for insulation. The innermost tube can be filled
either with water or with a heat transfer fluid to prevent freezing in cold climates. Obviously,
this kind of system is more complex to build and install than a simple hot water heating system.
Again, it might be easier to buy the solar collectors unless you have a lot of skill and
confidence.
Flat plate solar collectors, also used for residential hot water and heating, are usually easier
for a do-it-yourselfer to build. The design is fairly simple and straightforward. Flexible tubing
for the water is attached to an absorber plate and positioned inside of an insulated metal box. A
glass cover is used, which allows the sun to heat the water. As the water is heated, it is pumped
into an insulated storage tank and held for use as needed for bathing or washing dishes. With the
help of a good set of instructions, building and installing a hot water system using flat plate
solar collectors is a good project for people who are handy and motivated.
|
|
