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32nd European Photovoltaic Solar Energy Conference and Exhibition; 183-186, STR has recently developed new non-EVA encapsulants for PV modules based on polyolefin elastomers (POE’s). These materials have many advantages compared to traditional EVA based encapsulants like improved thermal and chemical stability, minimized corrosive potential, lower moisture vapor transmission rate (MVTR), improved electrical properties and PID resitance [1]. However, some similarities remain, like the need for a curing approach where the encapsulant is transformed from a thermoplastic into an elastomer during lamination. In this regard, lamination cycle optimization is required in order to obtain a good compromise between sufficient curing and optimal performance and reliability of the correspondent PV module. Special focus will be place on measuring the main properties that could be affected by poor cure levels like i) creep resistance, ii) adhesion to glass, iii) adhesion retention after DH85/85 and iv) light transmission. Lamination cycle times similar to standard EVA encapsulants are desirable.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 99-104, In this paper, two developments targeted at reducing the production cost of back-contact modules are presented. The first cost reduction potential is realised by replacing the conductive copper layer with aluminium with a very thin and locally applied copper coating using cold spray technology. This results in a 2% PV module cost saving while also meeting industrial requirements for production speed and reduction of contamination. Prototype mini-modules manufactured using this method have shown very good performances and passed selected IEC reliability tests (Damp Heat and Thermal Cycling).The second cost reduction comes from reduction of encapsulant usage. By using powder coating technology, encapsulant thicknesses below 100 microns can be achieved. This not only results in the reduction of encapsulant usage as compared to standard modules, but it also increases production flexibility. Application of powder coated encapsulant results in a cost reduction of 1%. An additional cost advantage of the implementation of thinner encapsulants is a reduction of conductive adhesive of at least 60%, which can result in an additional 2% cost reduction.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 173-175, This contribution describes thin-film barrier coatings to enhance the stability of silicon thin-film solar modules. Thin-film barriers are applied to protect the modules from degradation in humid environment. Demonstrator modules were exposed to indoor and outdoor tests to evaluate failure modes by electrochemical corrosion during operation. Test results reveal some major failure modes, but we demonstrate long lifetimes under operational conditions for certain modules without conventional encapsulation. These modules without conventional encapsulation showed less than 1% relative degradation during 1000 hours of damp-heat tests with light exposure at open circuit voltage. These promising results will guide the way to new encapsulation concepts for longer lifetimes and/or new low-cost concepts. This approach might be applied to any thin-film technology and will be an important aspect for consumer electronics with less strict requirements for very long-term operation.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 1-4, This paper reports on a novel and highly innovative technology to interconnect back-contact cells. First a background section explains the currently developed interconnection technologies. Then our novel concept is introduced: interconnection of the cells is achieved with a woven fabric, combining both conductive wires, needed for the interconnection, and insulating wires, crucial to avoid shunting between both polarities at the backside of the cell. Weaving also allows out-of-plane stress relief features. In the third section, we explain that our technology combines the advantages of multi-wire interconnection such as low-stress and reduced resistive losses with known and low-cost materials of traditional module assembly. We demonstrate that the technology can be tuned broadly in terms of costs and resistive losses using an optimized interconnection pattern. These loss simulations are also validated with the measured additional resistance in IBC test samples. Finally, first functional proof-of-concept with MWT cells as well as IBC cells have been fabricated.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 169-172, Different approaches like round wire interconnectors, shingled or back-contact cells have been presented in the past to improve the cell-to-module efficiency ratio by reducing the shading losses of interconnector ribbons. We present a new cell interconnector design based on a triangular cross section to further improve modules based on interconnector ribbons. We analyze the optical behavior of the concept and compare it with rectangular ribbons and round wire interconnectors. An evaluation of the new concept using optical ray tracing is performed. Results show an advantage in optical performance of 2.35% of the new concept compared to standard interconnector ribbons under perpendicular irradiation as well as 1.94% compared to round wires. An analysis using irradiation data (DNI) shows a superior optical performance of the TriCon-Concept. We find that in an elevation tracked module using TriCon 2.32% more light reaches the cell surface over the year compared to rectangular interconnectors (5BB) and 2.02% compared to round wires.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 48-52, Results of an electroless displacement process for the deposition of inexpensive solderable metal on physical vapour deposited (PVD) aluminum are presented. The dip – rinse – dry processing sequence for electroless metal deposition on Al is simple and easy to use because it does not harm the SiN antireflection coating and the screen-printed Ag metallization on the cells’ front side. Hence, finished cells can entirely be immersed into the electrolyte. The deposited metal layer is highly porous, but forms a massive alloy with common Sn/Pb/Ag solder at low temperature of 245 °C in the presence of no-clean flux. Because the molten alloy wets Al and copper well, we obtained strong solder joints for Sn/Pb/Ag coated copper ribbons on Al. The measured average 90° peel forces of ribbons soft soldered to thermally evaporated Al on shiny etched silicon and on the rear of alkaline textured monocrystalline Si PERC solar cells were up to 3.1 and 2.2 N per mm ribbon width, respectively. These values exceed 1 N/mm that is specified by the standard DIN EN 50461. Climate tests on single-cell glass-glass modules yielded 4.1 and 7.7 % power degradation after 200 thermal cycles from -40 °C to 85 °C and after 1000 h under damp-heat conditions at 85 °C and 85 % relative humidity, respectively. We attribute the too high power degradation after damp-heat test to residuals of the acidic flux which was used for soldering the cells in this first, older version of the developed technology.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 94-98, The interconnection of silicon solar cells by soldering causes thermomechanical stress due to different coefficients of thermal expansion of the materials involved, especially copper and silicon. In contrast to the current standard interconnection technology, using three to five flat ribbons to be soldered on continuous or segmented busbars on the solar cells front side and on large contact pads on the solar cells rear side, the Multi Busbar concept uses twelve to fifteen round solder coated copper wires to be soldered on a large number of small contact pads for each polarity. In this paper we present two finite element models, one for a solar cell with a common busbar-based interconnection and a second one for a solar cell using the Multi Busbar interconnection approach to analyze and compare the distribution of the thermomechanical stress induced by the cell interconnection. The results show only a slight vertical deformation of a contacted solar cell of 0.4 mm for the three busbar design and 2.2 mm for the Multi Busbar interconnection technology due to the non-symmetric pad layout and the aluminum metallization on the rear side. However, most parts of the copper interconnector (ribbons and wires) are plastically deformed because the tensile stress exceeds the yield strength of 100 MPa. In addition, the results indicate that there is only slight tensile stress in most parts of the silicon solar cell after the soldering process. For both interconnection technologies we detect local stress peaks and, on the rear side of the solar cells near the outermost contacts, we determine areas where the tensile stress reaches levels above 200 MPa that potentially cause defects.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 180-182, We report the 273W anti-glaring module with curved-frame structure and 0.85mm thickness glass. The optical simulation shows the reflectivity of curved module received by inspector is reduced 96.79% than flat panel by using Tracepro software. And the outdoor anti-glaring performance of this anti-glaring module has reached larger than 60% improvement than flat panel. However, the outdoor energy yield of anti-glaring module is lower (-0.19%) than flat panel. But the anti-glaring module still has a lot of benefits, like more efficient land usage, drainage and light weight (10.5 kg) which can be moved and installed quickly.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 196-199, AiSoVol project consists on the development, manufacturing and testing in a controlled environment of a new concept of photovoltaic modules, conceived for facilitating their use as architectural elements. Thus, the modules will be fabricated by encapsulating its constituent electrical elements (cells and interconnections) with lamination techniques at low curing temperatures and using transparent thermoplastic instead of tempered glass, as well as binding materials structurally strengthened by a grid made of high-tenacity yarns, such as the ones used in sail technologies and thus avoiding the need for aluminum frames. This type of solution will provide, due to the nature of the constituent materials, lighter PV modules which can adapt easier to different surfaces. In this paper the methodology followed to define a suitable lamination process compatible to obtain reliable AiSoVol photovoltaic modules is described. Results achieved from materials and processes validation will pave the way for manufacturing the prototypes in next project phase.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 105-109, Mosaic Solutions AS is developing a novel concept for conductive adhesives for use in electrical interconnection of solar modules. The goal is to provide an alternative to the current soldering process in module manufacturing, enabling lower process temperatures and reducing the amount of toxic elements, e.g. lead. The conductive adhesive is based on replacing solid silver flakes by polymer particles coated with a thin layer of silver. The main advantage of this concept, compared to conventional conductive adhesives, is a typical ten-fold reduction in silver consumption. We have investigated the electrical properties of conductive adhesives based on silver-coated polymer particles, and demonstrated the use of the conductive adhesive concept in module manufacturing. The results are promising, showing that the electrical conductivity is more than sufficient for use in solar modules, and that our conductive adhesive concept represents a promising and realistic alternative to soldering.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 176-179, The increment of the PV market has led to multiple PV installations which operate under non-ideal conditions. Heavy shading is expected in rooftop installations, Building Integrated Photovoltaics and solar powered vehicles. Demand of an increased energy-yield, despite of the non-uniform conditions render reconfigurable topologies a promising solution for such installations. Evaluation of the performance of a PV module can be performed either on the field or in a detailed simulation environment. The problem of the existing solutions is a large cost investment for constructing all potential topologies and the large time requirements for detailed simulation of the entire module. A simulation framework is proposed here which can significantly speed up the evaluation process of different reconfigurable PV module instantiations and conventional modules for different operating scenarios with a high accuracy level.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 165-168, To reduce cell-to-module (CtM) losses for aesthetically appreciated all-black modules we applied a black powder coating with low infrared absorption to standard back foils used in PV modules. Upon the application of such powder coating the IR reflective properties of the underlying substrate are largely preserved. For Cu foil substrates approximately 85% reflection in near-infrared was recorded, while for a white polyamide substrate reflection was 60%. These black, IR reflecting back foils were incorporated in single-cell laminates with n-Pasha bifacial solar cells. From these structures the potential Isc gain from the application of such coatings in PV modules as compared to conventional all-black modules is estimated to be 1.4 – 1.8%.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 191-195, The variable nature of solar energy required for its efficient use the complement of energy storage to adapt adequately the generation and production curves. As PV/T technology produces both electricity and heat energy, two storage devices should be necessary. Batteries are the most common method for storing electricity. Nevertheless, different technologies are available to store heat energy. Thermal energy storage can be classified into sensible or latent heat systems, depending if the substance that storages the energy changes its temperature during the process or its physical phase. Phase Change Materials (PCM´s) involve high amount of energy with small changes in volume and temperature so they are promising materials to keep temperature almost constant and store heat energy. In this work a complete study of different types of PCM for its application in PV/T is presented. For this purpose, different materials are classified in terms of its chemical structure and also by its use in PV/T technology. Great number of substances susceptible to be used as PCMs in a heat storage system is showed in the work by an exhaustive bibliography review. Only those PCM´s with melting temperature lower than 70 ºC have been taken in mind for this work. Upper temperatures do not provide enough PV efficient increase

32nd European Photovoltaic Solar Energy Conference and Exhibition; 42-47, We present a novel module design to increase the power output of bifacial modules without compromising the increased energy yield due to the bifaciality. This innovation includes a highly reflective interlayer between and around the bifacial solar cells and laminated between the front and rear encapsulant. Although bifacial solar cells in modules with transparent front and rear sides can absorb light incident at either side, the transmission of (infrared) light through the rear side reduces the Pmax. The lower Wp rating is seen as a drawback for bifacial modules. The innovative white bifacial modules show almost the same front side Isc and Pmax as a monofacial module and a 2.2% higher Pmax, due to increased Isc, compared to transparent bifacial modules. The same increase is found for the rear side Pmax. The bifacial energy yield for white bifacial modules, due to the higher Pmax for both sides, is much higher than the slightly higher ground reflected “albedo” light of regular bifacial modules.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 61-65, In a reconfigurable PV panel, the connections between groups of cells (cell-strings) can be rearranged in order to increase the overall power output under non-uniform conditions. In a traditional PV panel, current mismatch between the series-connected cells (due to irradiation differences of differential aging) limits the generated power output by either reducing the overall current or by bypassing the substring containing the limiting cells. A reconfigurable panel can respond to such a situation by changing the connections to a more favorable configuration, allowing the majority of the cells to operate at their MPP. This paper elaborates on such a topology and its components (high current switches, wiring). To get a clearer picture of the added value of such a reconfigurable panel, a detailed energy yield analysis was performed which includes the performance of those added components. The simulation model used for this analysis is calibrated with extensive measurement results. A comparison of that model and corresponding measurements will be discussed. The analysis shows that a reconfigurable PV panel can outperform the traditional panels when suboptimal conditions are predominant, as encountered for instance in BIPV. As a demonstration of the principle, a small-scale prototype was created and will be presented in this paper.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 53-55, We present here results on 60-cell modules assembled with 6 inch n-type interdigitated back contact (IBC) solar cells which were accomplished in close collaboration between ISC Konstanz, who developed an industrial process to fabricate IBC cells which we call Zebra cells [1] and Eurotron BV, who supplies equipment for back contact module assembly and processed Zebra cells into 60-cell modules. Interconnection is realized by electrically conductive adhesive (ECA) gluing of cells to a conductive copper backsheet. The module sandwich is laminated with commercially available encapsulation material in a standard laminator. We assembled three 60-cell modules so far reaching 294 W, 298 W and 303 W peak power at 1 sun respectively. The cell to module (CTM) power losses ranges between 1.1 to 1.8% relative which is an excellent result taking into account the absence of ISC gain due to finger reflection which eases the CTM loss for modules assembled with front contacted solar cells.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 56-60, A new concept for light weight solar modules is presented in this paper. The main difference to the common module type is the replacement of the frame at the laminates fringe by a lattice-like structure at the rear or at the rear and front side. Due to the smaller distances between the mechanical supporting elements the stiffness of the laminate itself can be reduced to a minimum, enabling the use of thin glass or alternative materials like for example polymer foils.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 110-114, Anti-reflective (AR) coatings address reflection losses at the PV glass surface of approximately 4% of normally incident light. These coatings reduce this loss by 1.5% to 3% and include sputtered multi-layer interference coatings and many variations of sol-gel derived, single-layer, porous silica. Early AR coatings suffered from poor field durability including delamination, corrosion and problems with contamination and soiling. In recent years, durability has improved and modern coatings are capable of long-term performance under moderate environment conditions. However, recent research has shown that these coatings remain susceptible to abrasion damage from activities such as regular cleaning, and to degradation from deployment in wet or humid environments. The structure of AR coatings create an inherent tradeoff between durability and optical performance, so more durable coatings tend to be at the lower end of the optical performance scale. In addition, the composition of the coating matrix itself can impact its long-term stability under humid or moist conditions. Now, in this work, we report on a novel method of creating structured porosity in highly durable, functionalized silica films that enable high optical performance with improved abrasion and moisture resistance. The resulting films are characterized optically and structurally and we report on their performance to standard and extended testing according to IEC specifications and to other applicable abrasion tests.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 187-190, A mini-module on one silicon wafer has been fabricated through assembling a small size of SIS (semiconductor-insulator-semiconductor) device taking on a bypass diode feature in a reverse saturation current, with HIT (heterojunction with intrinsic thin film) solar cell. The architecture is that the solar cell is on the front side while the inbuilt bypass diode is on the rear side. The data showed that the output character of the integrated devices possessed obviously hermaphroditical behavior at forward and reverse biases, which was available to protect the mini-system from deterioration upon shadowing. The integrated system as an independent output power device can be further optimized against the temperature influence.

32nd European Photovoltaic Solar Energy Conference and Exhibition; 200-204, A novel Window-Integrated Concentrated Photovoltaic (WICPV) system proposed suitable for window integration, has been fabricated and characterised at 1000 Wm-2 (higher irradiance)and 500 Wm-2 (lower irradiance). This paper investigates the use of a commercially available organic phase change material (PCM) RTÒ50 for limiting the temperature rise in the system within indoor testing conditions. The results demonstrate an average of 7.4°C reduction in the system temperature at 1000 Wm-2 and 4.8°C at 500 Wm-2. It also resulted in 17% increase in electrical power efficiency at 1000 Wm-2 and 6.5 % at 500 Wm-2 within the PCM incorporated system as compared to a naturally ventilated system. Further, differential scanning calorimetric technique has been applied to assess the thermophysical properties of the PCM as any erroneous data may affect the prudent selection of PCM for particular applications. The outcome of the DSC analysis performed on the PCM indicates 10.6 % underestimation in the reported melting peak temperature value of the PCM.

31st European Photovoltaic Solar Energy Conference and Exhibition; 160-163, Solar cells are composites of several materials. Due to this fact, the materials will determine the internal stresses of the cell. This paper considers one aspect of solar cell construction: the addition of conduction ribbons to the silicon surface of the cell. We use Raman spectroscopy to measure the stresses present in the silicon substrate, before and after the ribbons have been applied. We also consider comparing two methods of application: traditional soldering and a novel gluing method. Both methods significantly increased the stresses present, remarkably, by similar amounts. We conclude that the major source of stress is the ribbon itself; the type of adhesion method made little or no difference when measured with Raman spectroscopy.

31st European Photovoltaic Solar Energy Conference and Exhibition; 84-88, The Multi Busbar metallization approach changes the interconnection architecture on silicon solar cells essentially. Compared to a standard H-pattern design with three continuous soldered busbars, between 7 and 15 round copper wires are soldered onto more than 200 solder pads on the front side of the solar cell. Due to the different coefficients of thermal expansion of copper and silicon, mechanical stress is induced after the interconnection. In this work we simulate the mechanical stress induced by soldering with a finite element model and experimentally verify the simulated results. The characterization of the stress distribution in the solder joints of a 78 by 10 mm² cell section shows that the cell bow, which is a visible indicator for mechanical stress, rises approximately from 4 to 9 mm when the wire diameter is increased from 250 to 430 μm. Pre-stretching the interconnecting wires up to 1% before soldering causes a slight increase of the cell bow. The verified simulation model allows the identification of reasons for potential defects of solder joints after reliability testing and the determination of the areas where such defects most likely occur. In addition, the model enables a comparison of the thermo-mechanical stress distribution of different interconnection concepts.

31st European Photovoltaic Solar Energy Conference and Exhibition; 89-92, A detailed investigation of glasses with different anti-reflection (AR) coatings for PV modules is presented. Three types of coating structures (dense structure; closed-pores and open-pores) and their influence on PV modules are evaluated from a performance point of view. The results show that, compared to traditional open-pores structures, the dense structure shows an excellent reliability due to its unique structure: dense, smooth, hydrophobic surface and a polymer network between nano-particles. This type of AR coating also presents a good resistance to salt water spray or seawater immersion, damp-heat, humidity-freeze and abrasion. The AR coating with a closed-pores structure has an excellent performance (high optical gain) and a good reliability (good resistance to salt water or seawater, damp-heat and humidity-freeze), due to its novel structure: easily controlled porosity, closed and smooth surface and independent closed pores with no channel between pores. However, this type of AR coating is not suitable for desert application due to its low resistance to abrasion.

31st European Photovoltaic Solar Energy Conference and Exhibition; 104-107, Non-uniform operating conditions of photovoltaic modules lead to significant losses in the energyyield of PV installations. Irradiation and temperature differences between the cells of the module have a severe impact on the overall performance of the PV system. Variable shading due to clouds and casting shadows of nearby objects cannot be efficiently handled by the all series cell connection of industrial modules. Current mismatch in series-connected cells limits the generated power by either reducing the overall current or by bypassing the section containing the “poorly” performing cells. The configuration proposed in this paper allows different run-time instantiations of the module to allow the majority of the cells to operate at their Maximum Power Point. This is enabled through a network of additional components (switches, local dc/dc converters). The proposed module is evaluated in a simulation environment and the utilized model includes resistive and conversion losses due to the extra components. It is shown that the proposed configurable topology recovers most of the power lost due to current mismatch and outperforms conventional topologies under non-uniform conditions.

31st European Photovoltaic Solar Energy Conference and Exhibition; 149-152, The aim of this work is the development of an innovative module encapsulation technology based on a novel encapsulation foil with intrinsic conductive structures. The system is able to replace traditional interconnection schemes based on ribbon soldering, enabling a highly efficiency module assembly process and therefore increasing productivity and potentially reducing production costs. Conductive encapsulant foils are produced by combining advanced conductive inks with high-throughput roll-to-roll printed electronics technologies for the production of the conductive structures. Special focus is placed on developing printing and ink sintering processes for the intrinsic conductors, which i) maintain the properties of the encapsulant material, ii) meet stringent specifications regarding flexibility and mechanical strength of the conductive network and iii) reach high electrical serial and contact resistance after a typical lamination cycle.

31st European Photovoltaic Solar Energy Conference and Exhibition; 169-172, Deposition of Sn-Bi alloy on the n-type plated Ni/Cu grids of laser-doped selective emitter cells and on the p-type plated Ni/Cu grids of laser-doped bifacial cells is presented. A eutectic alloy composition was achieved by controlling the plating current density using a single plating electrolyte, however the Sn-Bi composition of the alloy was not uniform though the thickness of the deposit. It is shown that the plated alloy can be reflowed on the cell to increase uniformity and enhance bonding to interconnect wire during lamination enabling a low temperature interconnection process which effectively eliminates the solder-induced stresses on the solar cell.

31st European Photovoltaic Solar Energy Conference and Exhibition; 93-99, With TPedge we present an advanced frameless, polymer free encapsulation concept for silicon solar cells which addresses several disadvantages and significant cost factors related to conventional solar modules. “TPedge” represents a gas-filled, edge sealed, glass-glass module without polymeric encapsulation foils that requires less module production time. The cost calculation indicates 15.3% lower module material costs for “TPedge” production compared to the standard module production due to savings for encapsulation foils and frame. The results from successful and extended module testing such as 400x thermal cycling (PSTC = 0%), 2000 hours damp-heat (PSTC = -1.4%) or 5400 Pa (PSTC = -0.9%) mechanical load testing show that critical IEC tests are passed. Additional results show PID stability, hot-spot stability (PSTC = -0.6%) and successful hail impact testing (PSTC = - 0.5%). We consider the TPedge-concept to be ready for IEC certification.

31st European Photovoltaic Solar Energy Conference and Exhibition; 157-159, In this paper, AUO focuses on high performances of the back contact modules, as a function of different interconnection materials, lamination temperature and lamination time. The n-type interdigitated back-contacted (IBC) solar cells are used in the photovoltaic modules. The prepared PV modules have a front covered material/ethylene vinyl acetate (EVA)/IBC cells/EVA/conductive back sheet foil structure. AUO develops this type of module by using conductive adhesives for the electrical interconnection of the back of the cells with the electric conductive back sheet foil. The interconnection with different materials, including conductive tape, metal ingot and silver paste, has been applied in back contact cells. During the lamination process, temperatures (150 and 160 °C) and times (8 and 10 minutes) are varied experimentally in order to obtain a high module power.

31st European Photovoltaic Solar Energy Conference and Exhibition; 153-156, The physical and chemical properties of the encapsulation material define the long term stability of the module, its sensitivity to corrosion and potential induced degradation (PID) and the cell to module losses (CTM). Alternative materials to EVA do offer a possibility to increase the volume resistivity hence the stability against PID effect, better light transmissivity and enhanced stability during climatic testing. The paper investigated the performance of a newly developed encapsulation material, so called polyolefin elastomer (POE), on module level and compared it to the standard EVA material. For this we performed an investigation during damp heat (DH) testing for ribbons soldered or connected by means of conductive gluing to the solar cells. Further tests included extended humidity freeze (HF), a long-term PID, determination of cell to module losses for standard crystalline solar cells as well as IBC Zebra cells and the stability during thermo-cycling (TC). After 4400 hours of DH and HF40 test neither discoloration nor any larger power losses were found. The results after TC300 confirmed a superior performance for POE. We further found that samples with POE material show significantly less PID degradation and reduced CTM losses if compared to samples comprising EVA as encapsulation material.

31st European Photovoltaic Solar Energy Conference and Exhibition; 164-168, Current cell interconnection technology in a PV module is based on soldering three or four solder coated Cu ribbons on top and bottom of the cells, connecting them in series to create a string. An alternative approach being proposed by several equipment manufacturers is based on replacing the ribbons with multiple wires: this should enable at the same time higher module efficiency and significant cost reduction through consistent Ag paste reduction at cell level. On the other hand, a module reliability risk related to the introduction of a new technology has to be considered. Purpose of this work is to make a technical and economical assessment on the viability of a wire soldered interconnection with optimized metallization.

31st European Photovoltaic Solar Energy Conference and Exhibition; 100-103, DSM’s light trapping film (LTF) is applied to bifacial modules to improve the energy yield for vertical, east/west facing applications. The LTF increases the current both at test conditions (STC) and under high albedo with about 4% compared to planar solar glass, due to the better anti-reflection (AR) and light trapping properties. Without LTF, the current drop due to reflection at the air/glass interface increases from 4% to 45% for incident angles between 0 and 85°, With LTF it remains between 1 and 4%, coupling almost all light at all angles into the module. Optical, thermal and electrical modelling together with time resolved meteorological data results in time resolved output power. This shows that for east/west facing vertical modules 60% of the calculated energy output is generated at incidence angle >55°, versus 20% for equator-facing modules. Applying the annual energy yield (AEY) model to bifacial modules in vertical applications, we show that there is >6% gain in AEY by the addition of LTF. In general, as LTF is most effective for light incident at higher angles, systems that have a large contribution from either (or both) diffuse or ground reflected light will benefit the most from addition of LTF.

31st European Photovoltaic Solar Energy Conference and Exhibition; 146-148, To prevent PID (potential induced degradation), we have developed coating materials with high water-repellency. The coating solution consists of fluorine-hybrid of inorganic and organic components, and the resultant coated layer has attained environmentally tough properties. Only by wiping photovoltaic (PV) modules with cloth and the coating solution followed by drying, coated modules show that the losses of the normal powers (LNP) are less than 0.7%, after duration tests at 85°C and 85%RH, regardless of loading continuously electrical current. Further the present material has a function of anti-reflection (AR). A single coated layer on glass substrate of a c- Si PV module, gives ~3% of enhancement of the light-trapping performance (LTP) and to improve 2.99% of the power generation efficiency, respectively.