Photovoltaic module reliability model based on field degradation studies

Abstract

Crystalline silicon photovoltaic (PV) modules are often stated as being the most reliable element in PV systems. This presumable high reliability is reflected by their long power warranty periods. In agreement with these long warranty times, PV modules have a very low total number of returns, the exceptions usually being the result of catastrophic failures. Up to now, failures resulting from degradation are not typically taken into consideration because of the difficulties in measuring the power of an individual module in a system. However, lasting recent years PV systems are changing from small isolated systems to large grid-connected power stations. In this new scenario, customers will become more sensitive to power losses and the need for a reliability model based on degradation may become of utmost importance. In this paper, a PV module reliability model based on degradation studies is presented. The main analytical functions of reliability engineering are evaluated using this model and applied to a practical case, based on state-of-the-art parameters of crystalline silicon PV technology. Relevant and defensible power warranties and other reliability data are obtained with this model based on measured degradation rates and time-dependent power variability. In the derivation of the model some assumptions are made about the future behaviour of the products-i.e. linear degradation rates-although the approach can be used for other assumed functional profiles as well. The method documented in this paper explicitly shows manufacturers how to make reasonable and sensible warranty projections.

The contribution of dust to performance degradation of PV modules in a temperate climate zone

“…Table 3 estimates the minimum power expected to be produced by the PV modules after around 20 years. This is based on the work of Vázquez and Rey-Stolle (2008) who suggest that the minimum output power of a PV module at a certain time period of employment can be determined by: (a) taking into account minimum power output guaranteed by the manufacturer (at least 90% of its initial nominal power for after the first 10-12 years and at least 80% after 20-25 years employment), (b) manufacturing tolerance in module power (5%), and (c) measurement uncertainty (3%). Based on the results in Table 3, there are 2 of 7 PV modules (B and F) that produced less power than the predicted ones.…”

“…Losses caused by dust expresses the difference of electrical parameters output values of PV modules in clean conditions (after dust particles are washed away) and dusty conditions (no cleaning, dust particles still deposited on PV modules surface), whereas the losses caused by non-dust related factors indicates the difference of electrical parameters output values of PV modules from their initial condition (first deployment of PV modules) to their present condition in clean conditions. P max output, an important electrical parameter of a PV module frequently used by manufacturers to indicate its performance degradation (Vázquez and Rey-Stolle, 2008), was used to quantify the contribution of dust (C dust ) on the degradation of PV modules performance at ROTA. It is given by:…”

Economic and policy analysis for solar PV systems in Indiana

“…For years 19 and 20, we assume a mode value of 0.75% and min and max values of 0.3 and 3% respectively. (Skoczek et al 2009, Vazquez andRey-Stolle, 2008). The function for calculating the amount of electricity generated from the solar PV system with degradation considered in excel is shown in equation (9): (9) and represent the amount of electricity generated from the solar PV system in year and , respectivley.…”

Real‐time reliability test for a CPV module based on a power degradation model

“…Reliability models [10][11][12][13] based on performance degradation parameters are very useful in elements which main failure mechanism is degradation because it is possible to obtain reliability functions in a short time of accelerated tests or real working conditions. A reliability model based on degradation has been proposed for conventional Si modules by the authors in a previous work [14], in which a reliability model for silicon flat modules was presented, obtaining the main reliability functions from field degradation data. In that work, a large population of Si modules working during a long period of time was considered.…”