TÜV Rheinland provides an intensified hailstorm test for solar collectors and photovoltaic modules at its test center in Cologne. The new test bench has already been independently recognized by DAkkS, the national accreditation body for the Federal Republic of Germany. Now, for instance, 35-millimeter hailstones – as per IEC 61215 can be fired at photovoltaic modules with speeds of up to 27.2 meters per second. The experts still offer the test with 25-millimeter hailstones (speed of 23 m/s) as before. Compared with this test, the mass of the 35-millimeter hail is around three times greater, and the hailstones develop almost four times as much kinetic energy.
Jörg Althaus, business field manager Solar Energy at TÜV Rheinland, explains why the range of tests has been extended: "Quite rightly, insurance firms and project developers are increasingly insisting on the more rigorous tests as hailstorm damage to solar systems has increased significantly in the past few years." Hail is one of the most expensive causes of damage to solar systems in Germany. Alongside photovoltaic systems, evacuated tube collectors in particular were again affected by severe weather this year. According to insurers, major hail damage has also rocketed in Switzerland in the past two decades.
To curb rising costs for loss adjustment, Swiss insurance firms are therefore requesting tougher hail testing in hail resistance class 3 for photovoltaic modules and solar collectors, for example. According to TÜV Rheinland testing methods, the solar collectors and photovoltaic modules that pass the test comply with hail resistance class 2 (test with 25-millimeter hail) or 3 (35-millimeter hail). For photovoltaic modules in class 3, the recognized regulations of the Swiss Cantonal Fire Insurance Association prescribe hail bombardment with hail at least 30 millimeters in diameter with impact energy of 3.5 joules. TÜV Rheinland tests achieve more than twice as much energy with 35-millimeter hail.
Hail resistance classes also apply in the same way to solar collectors. However, as the current normative test principles for solar thermal collectors mainly relate to flat-plate collectors and do not describe evacuated tube collectors, the Swiss Cantonal Fire Insurance Association has also devised the special test specification no. 19. It contains a precise description of the firing location and firing angle as well as how the collectors are to be grouped and how pre-ageing has to be carried out in the case of plastic materials, for example. For instance, in addition to the area with the glass tubes near the collector housing, the evacuated tube collectors must also be fired at in the opposite area. In addition, each obvious weak spot must be hit by five more balls of ice. TÜV Rheinland also offers this testing method.
The first tube collectors have already undergone testing according to hail class 3 at TÜV Rheinland. "Switzerland is definitely a pioneer with its stricter requirements. However, there are signs that market development is also moving toward intensified hailstorm tests in other countries," said Althaus.
This test is another new addition to TÜV Rheinland's range of special load tests for solar systems. Recently, the independent testing service provider commissioned a new test bench to determine the resistance of building-integrated photovoltaic systems (BIPV) to driving rain. In 2013, TÜV Rheinland also launched a globally unique test program in which snow loads on photovoltaic systems mounted on sloping roofs can be realistically simulated. This is particularly relevant in regions with high snowfall. Inhomogeneous snow loads that fall on sloping roofs can be tested for modules in particular the glass and frame elements as well as the mounting systems. This is an important addition to the conventional horizontal load tests as specified by IEC 61215.
