Reliability is a key factor to achieve the planned energy yield of solar photovoltaic power plants. It is ensured by choosing good quality components when designing a photovoltaic system and by continuous monitoring of power output and rapid intervention at possible failures during the operation of the system. In this study, the photovoltaic system performance monitoring using performance models was analyzed. Due to gradual decrease of performance of the system caused by degradation, the new monitoring method was proposed. It includes the performance models with adjustable coefficients which are regularly updated in automatized procedure. This approach compensate for the ageing of the photovoltaic system and by analyzing the change of model coefficients during time the seasonal weather effect as well as ageing of the system can be evaluated. The proposed approach was validated by using measurements of photovoltaic system with rated power of 17 kW located in Ljubljana, Slovenia. The advantages of the method was found to be an automatized process of detecting faults and the possibility to additionally evaluate the sessional and ageing behavior of photovoltaic power plant.
B.04 Guest lecture
COBISS.SI-ID: 11348308Patent application protects the method and the device for determination of a measure of band gaps in optoelectronic components. The method relies on dependency between the emitted electroluminescence (EL) spectrum and the band gap of optoelectronic components, and on different levels of EL spectrum detection in different spectral ranges. EL spectrum is acquired as an image in two different spectral ranges, either with use of different cameras or with use of filters. The method comprises calibration and measurement procedure. Calibration procedure needs to be performed only once for every combination of optoelectronic device and measurement device. The result of the calibration is a correlation between the band gap and the ratio between two spectrally independent EL images. After calibration, measurement procedure only requires acquisition of two spectrally independent EL images, calculation of their ratio and application of the calibration relation, which makes the method very fast and useful as an in-situ measurement method for quality control of PV module production. The use of the method is demonstrated using commercially available state-of-the-art CIGS PV module, where lateral apparent bandgap fluctuation between 1.06 and 1.14 eV are detected.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 11696724To analyze the photovoltaic system potential for different locations and orientations, PV performance models coupled with solar irradiance databases are used. We have recently developed direct-diffuse-power-rating (DDPR) model that separately addresses the diffuse and direct irradiance components supplemented by angular loss compensation. In this study, the DDPR PV module performance model is extended to PV systems. The 17 kW PV system located in Ljubljana, Slovenia is used in this experiment to test the accuracy of the model which rendered 3.6% yearly root mean square error (RMSE) compared to 4.3% RMSE of basic model used as a reference. The major improvement occurs in the early mornings and late evenings when the diffuse component dominates. Also, the effect of longer averaging time intervals (which are usually utilized in many solar irradiance databases) on the accuracy of the PV performance models was researched. The averaging interval analysis showed, that up to 0.28% additional positive bias is induced for 1 hour averaging intervals compared to 5 minute one. With the use of the DDPR model’s feature of separating diffuse and direct irradiance, the model was used to estimate the loss or gain of PV system performance at different locations as well as orientations, different from optimal. The results for Ljubljana, Slovenia show that yearly temperature compensated performance ratio (PRT) can be 1.8% lower for certain orientations (e.g. vertical orientation facing south) compared to optimal orientation (south, 30° inclination) due to higher share of direct irradiance with higher solar incident angles. The contribution has been presented in the thematic area »Operation, Performance, Reliability and Sustainability of PV«, in which Blaž Kirn was honored by the »EU PVSEC Student Award«.
E.02 International awards
COBISS.SI-ID: 11472212