The impact resistance test is not only a problem for polymeric collectors but also for other collectors such as evacuated tube collectors. There are no real doubts about the suitability to assess the impact resistance using the current methods. Depending on the norm, certification scheme, or also building insurance codes the required impact energies may, however, vary. Furthermore, the risk of hail damage very much depends on the geographic location of the installation. It is, therefore, reasonable to assume that polymeric collectors – as all other collectors – will reveal a certain hail resistance allowing for installation in a possibly restricted area only.
A drop height of 2.0 m is acceptable for flat plate collectors with toughened glass general for flat plate. Drop heights of less than 1.0 m are acceptable for evacuated tube collectors.