• Energy Research

Photovoltaic industry has devices power improvement as a main target. This implies that technological advances are continuously implemented in production lines and their power improvements have to be monitored with the suitable key performance indicators. In this work, front size serigraphy design has been selected as process improvement and laminated unit power and cell to module ratio has been defined as the main key performance indicator. Real size silicon PV cells with three different front finger morphologies have been produced in industrial production lines by the use of two front size serigraphy designs. The modification of the finger dimensions (wide/height) from (183.0 μm/31.6 μm) to (184.0 μm/37.6 μm) and (140.0 μm/40.8 μm) leads to a redistribution of the majority produced cell power range from [4.10–4.15) W to [4.10–4.15) W and [4.20–4.25) W respectively. Concerning the cell production, it has successfully been monitored by the laminated unit power indicator along a month when shows an increment from 3.95 W to 4.20 W. Concerning module level, cell to module ratio per process cell range is selected as suitable indicator and monitoring during a year. In the specific case of [4.30–4.35) W cell range, cell to module ratio decrease from 7.7 % to 6.5 % The authors are thankful to Erasmus+ Programme, SafeEngine project, contract no 2020-1-RO01-KA203-080085, Spanish Ministerio de Ciencia e Innovación through project PID2020-117832RB-100, UMA 18-FEDERJA-041 for their support and to Isofoton and J. Alcaide and J. Rando from 4TENERGY S.COOP:AND, for their collaboration. Funding for open access charge: Universidad de Málaga / CBUA

Abstract Selective emitter diffusion technology has demonstrated a direct PV cell efficiency increase, due to a good ohmic contact and high blue response. These PV devices will be assembled to fabricate the final and commercial PV modules where the power enhancement is the most valuable one. The traditional encapsulant material is ethylene-vinyl-acetate (EVA) which ultraviolet wavelength cut off is placed in the region where selective emitter technology improvement is performed. Photovoltaic industry has developed innovate materials to overcome these issues. Among them, a low ultraviolet cut off EVA can be easily acquired. Our study demonstrates that with the correct PV module encapsulant configuration, part of the developed PV cell efficiency improvement related to selective emitter technology can be successfully translated at the end of the value chain; that is, the final PV module.

Abstract Crystalline Si solar cells as mounted in photovoltaic modules are historically encapsulated using ethylene–vinyl acetate (EVA) to provide mechanical support, protection against environmental exposure and electrical isolation. Nevertheless, new requirements in the final photovoltaic grid connection cannot successfully be reach by using this polymer current chemical composition. This phenomenon is known as the potential induced degradation (PID). Photovoltaic encapsulant industry has developed innovative materials to overcome this potential aging. One of these new materials is a thermoplastic commonly named as polyolefin. Photovoltaic modules using this encapsulation material have been fabricated in an industrial line and they have been subjected to PID tests. Our results demonstrate that polyolefin can successfully overcome PID test. Therefore it can be considered as a suitable EVA substitutive.

Abstract Silicon solar cell current–voltage (I-V) curve measurement is the final characterization procedure used in a photovoltaic (PV) industrial line. The illumination I-V curve measurements are of interest because they determine the solar cell power, relegating to dark characteristic in second place. Nevertheless, the growth of PV-building-integration can increase the possibility of the hot-spot phenomenon. The most effective approach to reduce this PV module failure is to directly identify and segregate malfunctioning cells in the production line. To achieve this objective, it is necessary to design a suitable silicon solar cell pass/fail protocol and to implement it in an industrial solar cell tester. This work focuses on the definition of a protocol for any industrial measurement tool for dark and reverse-biased conditions. The defined criterion includes three different orders: the first one segregates harmful Type I PV cells that exhibit a high hot-spot possibility, the second order separates solar devices that exhibit very high current leakage, and the third order separates PV cells with a double condition: Type II behavior that is very close to Type I with assembled power. This proposed dark-reverse measurement protocol has been appropriately defined for 125d150 and 150d195 PV cell sizes, and different batches for each size have been sorted using this scheme. The work also highlights the relevance of an in-line dark-reverse measurement criterion in a production-quality system. Finally, real size PV modules have been fabricated and they overcome the hot-spot endurance test.

This manuscript analyses changes in the optical parameters of a commercial alumina nanoporous structure (AnodiscTM or AND support) due to surface coverage by the ionic liquid (IL) AliquatCl (AlqCl). XPS measurements were performed for chemical characterization of the composite AND/AlqCl and the AND support, but XPS resolved angle analysis (from 15° to 75°) was carried out for the homogeneity estimation of the top surface of the ANDAlqCl sample. Optical characterization of both the composite AND/AlqCl and the AND support was performed by three non-destructive and non-invasive techniques: ellipsometry spectroscopy (SE), light transmittance/reflection, and photoluminescence. SE measurements (wavelength ranging from 250 nm to 1250 nm) allow for the determination of the refraction index of the AND/AlqCl sample, which hardly differs from that corresponding to the IL, confirming the XPS results. The presence of the IL significantly increases the light transmission of the alumina support in the visible region and reduces reflection, affecting also the maximum position of this latter curve, as well as the photoluminescence spectra. Due to these results, illuminated I–V curves for both the composite AND/AlqCl film and the AND support were also measured to estimate its possible application as a solar cell. The optical behaviour exhibited by the AND/AlqCl thin film in the visible region could be of interest for different applications.

We have studied differences in the interface between undoped and Al-doped ZnO thin films deposited on commercial Si solar cell substrates. The undoped ZnO film is significantly thicker than the Al-doped film for the same deposition time. An extended silicate-like interface is present in both samples. Transmission electron microscopy (TEM) and photoelectron spectroscopy (PES) probe the presence of a zinc silicate and several Si oxides in both cases. Although Al doping improves the conductivity of ZnO, we present evidence for Al segregation at the interface during deposition on the Si substrate and suggest the presence of considerable fixed charge near the oxidized Si interface layer. The induced distortion in the valence band, compared to that of undoped ZnO, could be responsible for considerable reduction in the solar cell performance.

Abstract Weak light performance of crystalline silicon solar module presents a clear dependence on the type of cell used, mainly wafer resistivity and shunt resistance. This paper shows that a proper wafer and cell classification can provide a further optimization opportunity. This means a well-controlled product fabrication and production line yield improvement without an additional cost. For these reasons a resistivity boron-doped Czochralski silicon (Cz–Si) wafer classification has been implemented as the first stage of a photovoltaic monocrystalline silicon solar cell production line which allows to process solar device batches with similar raw material properties. This new production stage leads to a narrower solar cell efficiency distribution and a tailored power photovoltaic module fabrication. After that, solar cell devices have been sorted by shunt resistance criterion. Their behaviors under weak light conditions have been carefully studied at cell and module levels. Finally, one and two diode models have been used to justify the obtained results.

Nowadays, the photovoltaic technology level development makes it the best option for its building integration as energy supplier. Nevertheless, its aesthetic appearance plays a relevant role because architect requirements go beyond the simple installation of solar devices on terraces. In order to fulfill their requirements, the typical white backsheet uses to be replaced by a black one. This simple change leads to a huge PV module performance reduction. In this work, it has been demonstrated that a suitable material selection allows to fabricate photo voltaic modules with a high architectonic integration, but without power reduction with respect to the most commercial solar devices. The former consists in the replacement of the typical glass front cover and the white backsheet by an antireflective glass and a black backsheet respectively. All the study has been developed on real size photovoltaic modules fabricated in an automatic line. The obtained results determine that those modules where black backsheets are used, suffer a power reduction equal to 8.66 W per fabricated module. Nevertheless, when in addition of the black backsheet an antireflective coating glass is implemented, the resulted PV modules present a more aesthetic presence without a detrimental of their power performance when they are compared to the standard PV modules. Additionally, the fabricated solar devices using the proposed configuration successfully overcome the most common aging tests. Política de acceso abierto tomada de: https://openpolicyfinder.jisc.ac.uk/id/publication/11131