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8th World Conference on Photovoltaic Energy Conversion; 488-491, BIPV (Building Integrated Photovoltaics) systems play an important role in generating electricity for net-zero energy buildings. Since BIPV modules and systems are fully integrated into the building envelope, their rear side is exposed to no or low ventilation, leading to increased operating temperature. Therefore, the performance of the modules – which decreases with increasing temperatures – is reduced, and the durability of the module – and its components (e.g. encapsulant, backsheet etc.) – may be impacted. Over the years, three different BIPV mock-ups have been installed at SUPSI (in Southern Switzerland) in different configurations: open-rack, BIPV-ventilated (partial ventilation) and BIPV-insulated (no ventilation) to investigate the impact of the operating temperature on the long-term performance of different BIPV modules. In this work, first, we show that since larger thermal stress accelerates UVinduced degradation of EVA (discoloration), there could be loss in Isc in BIPV configurations. Secondly, due to larger thermo-mechanical stress, there could be damaged cells and metallization, which causes loss in FF. Additionally, operating in a BIPV configuration does not mean that there will be faster degradation. There could be faster degradation only if there are larger thermal and-or thermo-mechanical stresses.

8th World Conference on Photovoltaic Energy Conversion; 95-97, We present passivating contacts for silicon solar cells using an interfacial layer of SiO2 grown by immersion in hot HNO3 and in-situ doped layers of both polarities grown by plasma enhanced chemical vapor deposition (PECVD). The doped layers are crystallized and their dopants are activated by rapid thermal processing (RTP) with a temperature profile similar to the firing of screen-printed metallization pastes, hence we call them fired passivating contacts (FPCs). After RTP, we apply hydrogenation to passivate defects, using thermal release of hydrogen from a SiNx reservoir layer during hot plate annealing at 450°C. We find that the kinetics of the hydrogenation process is characterized by a fast process associated to the passivation of defect states at the Si/SiO2 interface and a slower process likely related to the hydrogenation of bulk defects that are formed during RTP in the floating zone wafers used in this experiment. Despite the issue with bulk defects, we test the suitability of the FPCs for solar cells by depositing n- and p-type layers on the textured front and on the flat rear of single-side textured wafers, respectively. After co-processing in a single RTP step, we apply the optimum hydrogenation conditions identified above. Using an ITO/Ag metallization made at low temperature to fabricate proof-ofconcept solar cells, we obtain efficiencies up 20.5%.

8th World Conference on Photovoltaic Energy Conversion; 902-906, Aesthetics plays a major role in the development of BIPV products. Several BIPV module manufacturers attempt to mask the reflective metallic interconnects to obtain uniformly colored modules. This is achieved using expensive manufacturing steps, such as colored stripes with manual positioning. Inks could be an alternative to perform this process automatically. However, inks used in BIPV products must be extremely stable and do not alter their visual appearance over time. In this work, we propose a screening protocol to assess the long-term stability of seven commercial black colored inks used to mask ribbons. We apply it to coupons mimicking the structure of conventional glass/glass (G/G) and glass/backsheet (G/Bs) structures encapsulated with EVA and POE, and to one-cell modules with ink-coated ribbons with the help of an in-house developed ribbon coating equipment. The protocol includes three different test sequences. Sequence A involves 250 h of DH (85°C, 85%RH) followed by to 60 kWh/m2 of UV light exposure, sequence B the UV test only, and sequence C adhesion tests. The results show no degradation after the DH test and yellowing with unstable inks after the UV exposure. The electrical performance of modules coated with UV unstable inks, is only slightly affected (~-1%).

8th World Conference on Photovoltaic Energy Conversion; 1285-1288, PV systems' short- and long-term performances are often analyzed using satellite-derived insolation data. Despite the fact that higher uncertainties are associated with satellite-derived insolation data, no studies have been conducted to quantify the impact on the assessment of the PV plant's performance ratio (PR), used to judge the overall health status of a plant. In order to evaluate the performance of a PV system accurately, the uncertainty contribution needs to be carefully computed. In this work, we quantify: (1) the accuracy of two satellite-derived insolation data-set (opensource and paid service) with respect to the irradiance ground measurement obtained by properly maintained sensors; and (2) their effect on the uncertainty of the plant’s PR computed using satellite-derived insolation with different temporal resolutions. The uncertainty of PR computed using insolation data from a well-maintained and regularly recalibrated pyranometer computed as 3.6% (k=2), and it assumed constant for all temporal resolutions (daily, monthly and yearly) as a conservative assumption. The statistical evaluation shows that monthly and yearly PR values, which have an uncertainty of less than 5%, can be obtained using satellite-derived insolation data without having to deal with regular calibration and maintenance of an on-site pyranometer. We showed that depending on the quality of satellite-derived data and temporal resolution, uncertainty of PR differs. The PR computed using paid-service satellite-derived data has approximately a 1.7% lower uncertainty (k=2) than the PR computed using open-source satellite-derived data for the temporal resolutions considered (day and month), with the exception of the yearly resolution (for which this value is 0.6% lower).

8th World Conference on Photovoltaic Energy Conversion; 636-641, Silicon heterojunction (SHJ) solar cells and bifacial modules are expected to rapidly grow in the PV market, with their high power conversion efficiency, good performance at low irradiation and better temperature coefficients (TCs) allowing for improved energy yields. It is therefore increasingly relevant to have comparative analyses with conventional monofacial modules and market leading PERC cells. The aim of this contribution is to assess the performance of five PV modules on a rooftop monitoring station in Neuchâtel: two bifacial SHJ, two monofacial SHJ and one benchmark monofacial PERC. These three module types allow for detailed comparisons of performance enhancing factors both on the module structure and solar cell technology levels, allowing to decouple individual performance effects. After almost two years of monitoring, results show that bifacial modules yield 7.2% energy gains over both monofacial technologies, and 5% improved performance ratio (PR). For the corrected PR, current bifacial corrections may not fully describe the angular, optical and seasonal effects, as a 2.2% bifacial gain is still observed after temperature and rear irradiance corrections, leaving room for improvement in the current bifacial PR definition. In terms of temperature dependence, field-based TCs are found to be better for SHJ cells than PERC (-0.16%/°C vs. -0.31%/°C at STC, respectively), although performance gains also vary with irradiance conditions.