Actual PV module performance including spectral losses in the UK
ABSTRACT STC efficiencies are not sufficient to compare photovoltaic devices of different semiconductor material or device configurations. The energy yield changes as the variables of STC deviates from their original values when the modules are placed in various climatic conditions. The magnitude of this change for different modules is not always clear and needs to be investigated and modelled. A modeling and analysis method named site specific conditions (SSC) is demonstrated which is a measure-correlate-predict approach. It allows an accurate estimation of the actual energy yield for different sites based on the measurements at one single site. The method takes into account the effect of the physical operating environment and translates this to other meteorological conditions on the basis of physics related formulae. Our results show a large seasonal variation for modules for the different effects. For crystalline modules losses of up to 12% in the summer is due to the temperature effect while the multi-junction thin film losses of more than 30% in the winter is due to spectral changes and incidence angle effect for the UK.
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ABSTRACT: Presented is a method for calculating the power-productivity of photovoltaic (PV) installations with sunlight concentrators and multijunction (MJ) solar cells (SC) allowing for variation of their power efficiency in dependence on real operation conditions - spectral composition and sunlight flux density and also on temperature of multijunction cells. The yearly totals of specific electric power generated by a module at constant and variable efficiency values have been calculated. It has been shown that allowing for the joint effect of the sunlight characteristics and multijunction SC temperature on the photovoltaic module efficiency must be realized in simulating the module operation in any power generating systems. These allows excluding the overestimations of the yearly power totals generated by a solar installation in determining the power productivity.Photovoltaic Specialists Conference (PVSC), 2009 34th IEEE; 07/2009
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ABSTRACT: The performance of a roof mounted grid-connected photovoltaic (PV) system in Northern Ireland was monitored over 3 years on annual, seasonal and monthly bases. The overall system performance was adversely affected by low insolation conditions; 19% of total incident insolation was absorbed at irradiance level below 200 W/m2 and 67% below 600 W/m2, only 6·2% above 900 W/m2. In summer and winter, the PV and system efficiencies were 9·0 and 8·5%, and 7·8 and 7·5%, respectively and inverter efficiencies were 86·8 and 85·8%, respectively. The inverter for this particular system was oversized; 77% of the total DC energy produced when inverter's operating load was 50% of its rated capacity. The annual average monthly system performance ratio (PR) was 0·61 with seasonal variation 0·59 to 0·63. The average monthly PV, system and inverter efficiencies over the whole monitored period were 8·8, 7·6 and 86·8%, respectively. The main losses of the system were inverter DC/AC conversion loss, inverter threshold loss and low insolation loss. Copyright © 2007 John Wiley & Sons, Ltd.Progress in Photovoltaics Research and Applications 01/2007; 15(4):353 - 368. · 7.71 Impact Factor