24 - 28 October 2016 • Marina Bay Sands Sands Expo and Convention Centre, Singapore
Technology Developments in REC: Silicon to Module
REC is a vertically integrated manufacturer of multi-crystalline solar panels with production facilities in Norway and Singapore. This vertical integration allows us to harmonize and industrialize the technology advancements in each division within the company. From successfully growing G5 ingots in a quad furnace using the low cost Elkem Solar Silicon (ESS), to launching a high efficiency module combining multi-busbar, PERC and half-cut cell technology, REC has effectively utilized its entire value chain to remain competitive in the $/W race. In addition, the optimized combination of these different technologies has also resulted in improved performance in reliability and field tests. In this presentation, details of the various technical achievements within the various divisions of REC will be presented.
Silicon heterojunction photovoltaic module with conversion efficiency of 23.8%
The silicon heterojunction (SHJ) solar cell, which we had introduced as an innovative structure for the high-efficiency solar cell, have shown its record-breaking potential and reached to the confirmed efficiency of 25.6% (designated area, 143.7 cm2) at research level in 2014 by adopting the back contact architecture.
For the next step, we are developing the technologies to fabricate high efficiency modules, by combining the back contact type SHJ solar cells with our expertise and experience of high efficiency photovoltaic modules HITTM cultivated in our mass-production history.
As a result, we recently achieved a photovoltaic module conversion efficiency of 23.8% and output power of 275.3 W (aperture area, 11,562 cm2) at research level confirmed by the National Institute of Advanced Industrial Science and Technology (AIST). This output power is the highest record in 72 cells photovoltaic modules using crystalline silicon wafer of 5 inch size.
In this work, we present an overview of the recent results obtained at ISC Konstanz on interdigitated back-contact (IBC) ZEBRA cells and their module interconnection. We demonstrated the transfer and scaling-up of the cell process to the pilot line production for more than 1100 solar cells with best efficiency of 22 %. The stability of the process for different Cz Si-wafer suppliers and the key-factors to achieve high-efficiency cells -i.e., material quality, doping profiles, patterning geometry, etc.- has been investigated: a clear insight of the features and performance of the cells will be presented.
With the clear aim to launch the BC technology to the market, ISC konstanz is currently working on several projects aiming to optimise a simple module manufacture process. In our last achievement, we obtained 300 Wp on 60 Zebra-cells module, using Eurotron back-contact module assembly line. An overview of the different projects for the module integration of the Zebra cells will be discussed with particular focus to the advantages introduced by the bifacial characteristic of the Zebra cells, a rare feature for the IBC cell architectures. In the end, we demonstrate the cost-effective of the technology presenting COO calculation between 0.4-0.7 US$/Wp for module of 300-310 Wp; these results makes the Zebra concept one of the most low-cost and high-efficiency PV technology currently available on the market.
Smit Thermal Solutions specializes in thermal processes for high-volume mass manufacturing, particularly for CIGS and CdTe PV production lines. These thin film production lines include a large number of processes, each of which is crucial to obtaining high overall yields of good cells. Reliability is a must. For thermal processes, this reliability is achieved by designing reproducibility and controllability into the systems. We share inside insights and data on how to ensure reproducible process settings over long periods of time, and how to implement a wider thermal process window to allow the necessary flexibility for future developments.
A bifacial module can produce additional energy by converting solar energy to electrical energy from both sides of the module. Despite the advantages of higher energy yield provided by the bifacial structure, the front side performance of these modules is lower compared to the standard glass/backsheet modules due to the loss in the cell-gap region and the near infrared light escaping through the bifacial modules. This study investigates the selective use of coating on the rear glass to recapture the light while maintaining the bifaciality of the module. To recapture the light loss in between cell-gap region, the reflective coating is printed selectively at only the cell-gap region. To recapture the near infrared escaping the bifacial cell and module, specially engineered coating to reflect the near infrared light is printed on the rear glass.
Recovery Technology of Intact Wafer from End-of-life c-Si Photovoltaic Module
In terms of environmental issues, the global PV market significantly grew up to 50 GW in 2015 with a 25% growth rate compared to PV market in 2014, which leads to a huge amount of PV waste in the future. The PV waste can increase faster than expected, because the undesirable factors of the module such as optical detect, power loss, glass breakage, etc. accelerate shortening of its lifespan. Most people are aware that recycling is the most desirable way for the proper management of PV waste. In this talk, I will present various recycling technologies for c-Si PV modules and the recent KIER’s results as well. Especially, KIER’s new technology for intact Si wafer recovered from the module will be introduced with a consideration of breakage mechanism of the wafer during the module separation process. A PV performance of reclaimed wafer-based cell showed a high efficiency of > 17%.
In order to get more power, solar module manufacturers are trying many innovation methods. In this work the benefits of using high reflection rate white encapsulant over a traditional EVA is presented. Optical performance of white encapsulant is demonstrated to reflect more light between cells back to module comparing to back sheet or back glass does. Different kinds of measurements demonstrate a different relative increase in the power rating of the PV module. White EVA seems to bring 1 – 2 extra watts if compared with an ordinary G/Bs panel, and around 1 watt increase if compared with panel using a high reflectivity back sheet. Wattage increase is remarkably high in double glass technology where white EVA implementation, gives around 8 watts of additional power to the panel. Analysis data and economic benefits are reported in this article to support the viability of this solution that has the possibility to become a popular main-stream technology in the near future.
The article also demonstrates viable and inexpensive methodology that eliminates all kind of problematic deriving from using white encapsulant in laminators and launches this material implementation on industrial scale. Never been used in the PV industry before, electron beam technology treatment on the finalized encapsulant, produces a controlled pre-crosslinking effect that allows the elimination of problems in the production such as white overflow on cells and ribbons or cell shifting in double glass technology. The module makers can therefore keep the same structure of the PV panel without adopting longer lamination conditions. Lamination techniques are also presented to demonstrate the simplicity of the integration of this new encapsulant into the PV panel that doesn’t need any laminator change or upgrade.
Finally by achieving higher production yield rates, the module maker have a direct benefit in term of cost saving.
Potential-induced degradation of the shunting type (PID-s) of silicon solar cells is attributed to planar crystal defects at the cell front surface. These so-called stacking faults with a length of a few micrometers, penetrating the p-n junction, behave as shunts when they are decorated with Na atoms. While the fundamental nature of PID-shunts is clear so far, the process of stacking fault formation is subject to ongoing investigations.
Recent work reveals that stacking faults grow in length and depth under sustained high voltage stress. This is a strong hint that the stacking faults evolve first upon application of the high voltage stress to the cell. A corresponding microscopic model of PID-shunt generation will be discussed in context to PID-s mitigation approaches as well as implications towards PID-s recovery modes.
Recent advancements in First Solar’s thin-film module technology have demonstrated significant efficiency enhancements, setting a new benchmark for PV solar systems. With current production efficiencies at more than 16.4% and future Series 5 and Series 6 modules targeting production efficiencies upwards of 17%, performance improvements are being delivered at a rapid and sustained rate. A key component of this demonstrated performance advantage is the technology’s superior energy yield, which is enhanced further in hot and humid climates, such as SE Asia. It’s here that thin-film CdTe modules have an inherent technology advantage compared to traditional silicon modules due to a superior spectral response and temperature coefficient. Today’s presentation will review First Solar’s recent technology developments and explore the current tangible energy production benefits which make this technology a more competitive and scalable source of energy.
Reliability and Durability of PV Modules in PV Systems
The long term reliability of photovoltaic (PV) modules is critical to the cost effectiveness and the commercial success of PV. Today most PV modules carry a power warranty of 80% of initial power through 25 years of deployment. Data on long term performance of PV systems indicate that PV modules can survive for 25 years with less than 0.8% per year power loss. To achieve such performance the modules must be 1) designed correctly, 2) fabricated under an adequate quality management system (QMS), 3) shipped/transported to the installation site using an adequately tested method, and 4) installed using installation procedures also under an adequate QMS in a well-designed system.
There are three organizations that are cooperating to ensure that all four areas are addressed. PVQAT is working on developing improved accelerated stress tests to qualify design and have developed a Guideline for Module Manufacturing QMS. IECRE is developing a conformity assessment system for the PV power systems. IEC bridges the gap between the other 2 by preparing the international standards for use by the IECRE system. This talk will describe how these three groups are providing a system that will help investors balance risk versus cost in design, construction and operation of a PV power system.