Evaluation of current standards and practices for the simulation of wind-blown sands and their applicability as accelerated ageing tests for PV modules

Sand movement is categorized in saltation, surface creep and suspension. For the simulation of stresses caused by sand movement, suspension and saltation are of particular importance. As a basis for a simulation the annual amount of sand affecting a single photovoltaic (PV) module in a particular location is estimated. Basing on these estimations, this work discusses three test methods which are applied to electronic products or military equipment as potential technical test procedures for PV modules. The test methods within MIL STD 810G, IEC 60068-2-68 and IEC 60529 vary in terms of wind velocity, particle density, particle dimension and distribution of sand grains. The relevance of a wind-blown sand or a dust test is very crucial in arid regions. However, each individual location of a PV system has other basic conditions (e.g. grain characteristics, wind velocities,...). The expected service life of PV systems requires a reproducible test procedure representing long-term ageing and exposure effects. The main question is the reliability and the electrical safety of PV modules and other system components. Critical effects like abrasion on backsheets, cables, connectors or junction boxes could cause a loss of isolation. For the local energy yield it is furthermore relevant if shading effects caused by dust and sand are quantifiable to define cleaning cycles. Abrasion of glass can further influence the long-term power output of a PV system. Within this work furthermore alternatives to quartz dust as test medium are discussed, since quartz dust used for abrasion tests is known to pose great danger to test personnel by causing silicosis. The test methods discussed are open test systems with a single impact or closed circuit systems. The aim is to define an applicable test sequence which enables a confirmation of a resistance against weather phenomena with wind-blown sand. Consequently this work derives input for future standardization progress and the finding of an applicable test method.