What is the best angle to position my collectors?

This answer depends on what you are trying to accomplish. For simple Domestic Hot Water systems you should try and position you collectors at the same angle as your latitude. For systems that are tied into the home heating system, as in a combisystem, you should position you collectors 15 degrees higher than your latitude. For summertime use only systems, as in a pool system, you should position your collectors at your latitude minus 15 degrees.

For systems that have a high solar fraction, i.e. 75% or greater, you should increase the angle of incline in order to decrease your summertime production slightly.