Manufacturers of solar panels, also known as photovoltaic (PV) modules, regularly subject their products to reliability tests intended to provide accelerated testing of degradation and failure modes. One important factor in various degradation and failure modes is exposure to ultraviolet (UV) radiation in sunlight, specifically in the UVA (320-400 nm) and UVB (280-320 nm) wavelength ranges.
PV manufacturers therefore include UV light exposure testing as part of their product reliability analysis. Indeed, UV exposure testing is required for PV module certification to industry standards such as International Electrotechnical Commission (IEC) 61215 and 61646, which are widely adopted. These standards call for exposure of PV modules to at least 15 kW-hr/m2 of UVA and UVB radiation for approval of new product designs. It is widely acknowledged that actual UV exposures greatly exceed this level after only a few months of operation in the field. Therefore more extensive UV exposure testing is desirable.
However, existing UV exposure test equipment is not optimized for high-volume manufacturing requirements and is inadequate to meet the growing PV industry's testing needs. One issue is exposure uniformity. If uniformity is poor, either test quality is compromised or the exposure area must be over-sized compared to the test samples, resulting in higher cost per sample tested. Another issue is floor space. In some systems, modules under test are loaded horizontally onto a test table to be exposed by over-hanging UV lamps. For a large number of exposed modules, this requires significant floor space, since typical PV modules in use today have dimensions up to 1 m×1.6 m.
In view of the shortcomings of existing equipment, there is a need for an improved apparatus for UV exposure testing of PV modules.