Temperature accelerated life test on commercial concentrator III–V triple‐junction solar cells and reliability analysis as a function of the operating temperature

Abstract

A temperature accelerated life test on commercial concentrator lattice-matched GaInP/GaInAs/Ge triple-junction solar cells has been carried out. The acceleration of the aging has been accomplished by subjecting the solar cells at temperatures markedly higher than the nominal working temperature inside a concentrator, and the nominal photo-current condition (820 X) has been emulated by injecting current in darkness. Three tests at different temperatures have been carried out. The failure distributions across the three test temperatures have been fitted to an Arrhenius-Weibull model. An Arrhenius activation energy of 1.59 eV was determined from the fit. The reliability functions and parameters of these solar cells at two nominal working conditions 80 and 100 ı C have been obtained. In both cases, the instantaneous failure rate function monotonically increases, that is, the failures are of the wear-out kind. We have also observed that the reliability data are very sensitive to the nominal temperature condition. In fact, at a nominal working condition of 820 X and 80 ı C, assuming that the concentration module works 5 h per day, the warranty time obtained for a failure population of 5% has been 113 years. However, for a nominal working condition of 820 X and 100 ı C, the warranty time obtained for a failure population of 5% has been 7 years. Therefore, in order to offer a long-term warranty, the working temperature could be a key factor in the design of the concentration photovoltaic systems.

Electrical-thermal analysis of III–V triple-junction solar cells under variable spectra and ambient temperatures

“…Reliability analysis on 3J solar cells have shown that, at operating conditions of 820Â and 80°C, the warranty time was found to be 113 years; at 100°C however, the warranty time was reduced to 7 years (Espinet-González et al, 2014). It is also worth noting that, in high temperatures (over 120°C, 1Â), the voltage output of the low energy band-gap germanium subcell decreases to almost zero (Helmers et al, 2013;Nishioka et al, 2005).…”

Degradation mechanism(s) of GaAs solar cells with Cu contacts

“…The main difficulty with this generally applied method is that activation energy determination is difficult and hence there are very few activation energies reported for solar cell degradation [38][39][40][41] increases. This study utilizes initial ALT of 4h at 300 • C, which covers all three scenarios (GEO, LEO and extreme) if the more optimistic E a of 1.02eV reported in a study conducted by Nuñez et.…”

Semi‐quantitative temperature accelerated life test (ALT) for the reliability qualification of concentrator solar cells and cell on carriers

“…In order to design a semi‐quantitative temperature ALT, the following assumptions have to be taken into account: Life model : We assume that temperature accelerates the life of the solar cell/CoC following the Arrhenius model , as shown in previous temperature ALTs on solar cells/CoCs . where L ( T ) is a temporal measurable characteristic of the life of the device under test which depends on the temperature, k is the Boltzmann constant, E A is the activation energy of the mechanism which causes the failure and C is a parameter of the Arrhenius model which depends on the L ( T ) used. Working time : Concentrator solar cells work only for daylight, and their electricity production is variable, having a peak at about the solar noon.…”