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The primary goal in the qualification testing is to identify the short-term reliability issues in the field. The primary goal in the accelerated reliability or lifetime testing is to identify the initial, operational and ultimate reliability issues in the field so that the lifetime can be predicted and warranty can be protected. The test-to-failure (TTF) testing is a compromise and it falls between these two extremes of qualification testing and lifetime/reliability testing. One of the major reliability issues of photovoltaic modules in the field is the hotspot endurance. A TTF study involving hotspot stress along with thermal cycling stress is undertaken and is presented in this paper.

Qualification testing of photovoltaic modules is a set of well-defined accelerated stress tests with strict pass/fail criteria based on functionality / performance, safety / insulation and visual requirements. This paper, third in series from the Photovoltaic Testing Laboratory of ASU / TUV Rheinland PTL, compares the overall failure rates obtained in three consecutive periods: 1997–2005, 2005–2007 and 2007–2009. This paper also presents a distribution of failures, for the 2007–2009 period, among the four pass criteria defined in the standard: Visual failure (for example, extensive delamination), dry insulation failure (safety issue), wet resistance failure (safety issue) and performance failure (power drop).

We report the results of qualification testing of Emcore's sixth generation III–V multi-junction solar cell — the 30% class GaInP2/Ga(In)As/Ge ZTJ cell. The ZTJ cell has undergone space qualification within the Air Force ManTech program utilizing the American Institute of Aeronautics and Astronautics (AIAA) S-111-2005 standard. The S-111 tests comprise characterization tests and qualification tests. The objective of the characterization tests is to provide electrical, mechanical, and environmental data at the cell level to aid in the accuracy of on-orbit power predictions. The qualification test objective is to validate the present materials and manufacturing processes used in ZTJ cell and CIC level assemblies for Geosynchronous Earth Orbit (GEO) applications. The ZTJ cell used in this qualification program is characterized by a beginning of life (BOL) maximum power point efficiency of 29.5% (135.5 mW/cm2) under simulated AM0 illumination at an operating temperature of 28 °C.

Spectrolab is qualifying its fourth generation of terrestrial concentrator multijunction cells (C4MJ). Prototypes of this product have been tested with an average efficiency of 40% at 50 W/cm2 illumination. This new generation is a departure from previous production technology in that, for the first time, it employs metamorphic rather than lattice-matched technology.