To cover the ROOS-solar collector with glass or to insulate it is absolutely superfluous.
A solar pool heating operates within the low-temperature domain. The difference between the temperature of the circulating water and the surrounding temperature consists of only a few degrees. The loss of heat can be neglected. It is important that the heat absorbed and transmitted to the water flowing through the collector is immediatly transported into the pool. The pool functions as a heat accumulator.