The performance of crystalline silicon photovoltaic solar modules after 22 years of continuous outdoor exposure

Abstract

This paper presents the results of 40 silicon-based photovoltaic solar modules originating from six different manufactures which were tested and characterised originally at the European Solar Test Installation, (ESTI), in the period 1982-1984. These same modules have been re-measured in 2004 after 20-22 years of continuous outdoor weathering. These modules are a subset 'Rack C' of the JRC Ispra outdoor test field where examples of diverse generations of PV technologies have been subjected to long-term climatic exposure. We have compared the results obtained from these samples with the typical guarantees which are given by module manufacturers and we can see that in general the manufacturers are conservative with their power guarantees. Most modules exceed the minimum power levels given for 10 years exposure, even after 22 years in the field. The results presented in this paper indicate that the degradation observed in the field is comparable to that observed in Type Approval Testing. This result not only validates the testing and stress levels applied in the Type Approval Tests, but also would indicate that (with the majority of modules exceeding the level of 92% of P max after 20 years) the actual lifetime of these products is significantly more than 20 years.

Performance of Photovoltaics Under Actual Operating Conditions

“…The performance of PV modules varies according to the climatic conditions and gradually deteriorates through the years (Adelstein & Sekulic, 2005;Cereghetti et al, 2003;Dunlop, 2005;Osterwald et al, 2006;Sanchez-Friera et al, 2011;Som & Al-Alawi, 1992). An important factor in the performance of PV technologies has always been their long-term reliability especially for the new emerging technologies.…”

“…Other degradation mechanisms include metal mitigation through the p-n junction and antireflection coating deterioration. All the abovementioned degradation mechanisms have been obtained from previous experience on c-Si technologies (Dunlop, 2005;Quintana et al, 2002;Som & Al-Alawi, 1992). …”

Photovoltaic module reliability model based on field degradation studies

“…The degradation rate for crystalline silicon modules is significantly smaller than that for amorphous Si and CIS modules. Taking crystalline silicon PV modules as a reference, the yearly linear power reduction rate varies from 0Á3% 24 to more than 1%. 15 However, PV module technology is improving continuously 25 and solar modules manufactured in recent years are expected to have a lower power reduction than solar modules manufactured in the 1980s, which is the case for most modules involved in the studies detailed in Table I.…”

“…The main conclusion of these studies is that solar modules do not usually fail in a catastrophic way but experience a steady power degradation over time. 5,[15][16][17][18][19][20][21][22][23][24][25][26] This degradation process has been reported to undergo two different stages: within the first year of exposure solar modules exhibit a rapid degradation (1-3%), 18,19,27 thereafter a slower linear degradation rate is observed (0Á5-1Á0%/year). Another important issue that affects PV module performance is that the variability of PV module power increases over time.…”

Outlier identification in outdoor measurement data - effects of different strategies on the performance descriptors of photovoltaic modules

“…The standard deviations for 1000W/m 2 and 100W/m 2 are reduced to 1.9% and 1.4%, respectively . For those modules deployed at the sites with moderate climate, they experience a relatively low degradation rate of 0.3-1% [8] [9]. Thus , the analyzing result uncertainties might be even greater than the degradation rate of the parameter investigated , which leads to the obtained results seem to be unchanged .…”