Solar hot water collectors are used to transfer the sun energy to the heat transfer fluid, which then transfers the energy to a hot water storage tank.   There are many different forms of solar collectors, from unglazed pool collectors, to traditional flat plate collectors, to evacuated tube collectors.  Each type of collector has its own strengths, and each one has a place.  The most commonly used collectors for domestic hot water and space heating are the flat plate collectors, and the evacuated tube collectors.  Here are a few pictures of solar hot water collectors that we have installed.