World PV Research Articles

Toward Efficiency Limits of Crystalline Silicon Solar Cells: Recent Progress in High‐Efficiency Silicon Heterojunction Solar Cells

AbstractPhotovoltaic (PV) technology is ready to become one of the main energy sources of, and contributers to, carbon neutrality by the mid‐21st century. In 2020, a total of 135 GW of PV modules were produced. Crystalline silicon solar cells dominate the world's PV market due to high power conversion efficiency, high stability, and low cost. Silicon heterojunction (SHJ) solar cells are one of the promising technologies for next‐generation crystalline silicon solar cells. Compared to the commercialized homojunction silicon solar cells, SHJ solar cells have higher power conversion efficiency, lower temperature coefficient, and lower manufacturing temperatures. Recently, several new record efficiencies have been achieved. To meet the continued demand for high‐efficiency solar cells, expectations for large‐scale mass production of SHJ solar cells are rising. To approach the efficiency limit and industrialization of SHJ solar cells, serious attempts have been made, yielding higher short‐circuit current, open‐circuit voltage, and fill factor. In this article, these recent advancements are reviewed, which reveals the future roadmap for approaching the efficiency limit.

Performance Analyses of 15 kW Grid-Tied Photo Voltaic Solar System Type under Baghdad city climate

The performance analyses of 15 kWp (kW peak) Grid -Tied solar PV system (that considered first of its type) implemented at the Training and Energy Research Center Subsidiary of Iraqi Ministry of Electricity in Baghdad city has been achieved. The system consists of 72 modules arranged in 6 strings were each string contains 12 modules connected in series to increase the voltage output while these strings connected in parallel to increase the current output. According to the observed duration, the reference daily yields, array daily yields and final daily yields of this system were (5.9, 4.56, 4.4) kWh/kWp/day respectively. The energy yield was 1585 kWh/kWp/year while the annual total solar irradiation received by solar array system was 1986.4kWh/m2. The average power losses per day of array, system losses and overall losses were (1.38, 0.15, 1.53) kWh/kWp/day respectively. The average capacity factor and performance ratio per year were 18.4% and 75.5% respectively. These results highlighted the performance analyses of this PV solar system located in Baghdad city. The performance can be considered as good and significant comparing with other world PV solar stations.

A Breakthrough in Plating for Solar Cell Metallization

Today’s world PV market is dominated by standard crystalline solar cells (so-called Al-BSF cells) and part of the market is shifting to PERC solar cells. The shift is obtained by introducing three additional process steps to the standard process (rear side cleaning, passivation and laser opening), and allows a gain of typically 1% absolute in efficiency. Next generation c-Si technologies should feature higher voltage solar cells with higher efficiency and less processing steps in the manufacturing, allowing for further cost reduction, both at the PV panel level and for the final cost of solar electricity. AMPERE, H2020 funded project, (http://www.ampere-h2020.eu/) focuses on technologies with such a potential and capitalizes on the high tech investments made in Europe over the last decade for establishing advanced manufacturing processes for crystalline silicon heterojunction (SHJ) solar cells and modules. A main cost factor in such cell processing, as expected, was found to be the silver based metallization. Estimating a silver paste consumption of 200mg, for a bifacial SHJ cell, and a silver paste cost conservatively estimated at 800 USD/kg for low-temperature paste, in a 23% efficiency cell, the silver cost will be around 3.0c$/Wp accounting for almost the 20% of the total industrial cost of the SHJ bifacial cell. Silver should be replaced on a large-scale basis by a more cost-effective material. Copper (Cu) is the intended substitute. The expected introduction of Cu into mass production is delayed mainly due to the big progress in screen printing and also due to some technical issues in reliability, adhesion that have to be resolved as also appropriate equipment and processes need to be available with the appropriate footprint and productivity. Comparing the state art of PV industrial plating a breakthrough plating process for SHJ copper metallization will be presented. Selective processing technique based on dynamic liquid drop/meniscus (DLD/DLM) allows metallization of solar cell fingers and bus bars without using any kind of lithography [1]. Figure 1.A presents the 2D view of how the DLD works. The system is composed, in a principle implementation, by an internal jetting outlet where a liquid flow is forced, and an external recalling inlet where by a depression the liquid is recalled back into the system. The input channel, confined by rigid wall (i.e. solid material), pumps a constant liquid flux that, depending on the input nozzle dimension, fixes the velocity of the liquid exiting the input channel. Due to a lower pressure in the surrounding of output channel, the airflow (gas) sustains the liquid (figure 1.A: black arrows in the red liquid) forming the DLD. The dynamic characteristics is due to the constantly refreshment of the liquid, during time, inside the drop. As the substrate gets in contact with the DLD, a DLM is formed, as shown in figure 1.B. Such technique allows to touch the surface of a solar cell only in specific defined positions and to perform electrochemical plating treatments in a localized manner. In DLM speed of liquid is in the meter per second range, like in a jet-plating technique, allowing to have fast deposition rate of metals. Due to the fast speed of liquid flow, the plating rate of copper is in the range of micron per seconds. In figure 1.C is shown an 100 micron width meniscus formed on glass substrate and the direction of movement of the DLM is indicated by the arrow. The ongoing result of EU Horizon2020 AMPERE project relative to copper metallization on ITO with fingers down to less than 60 micron width will be presented showing how by special reduction technique of ITO plus a thin barrier layer of nickel (figure 1.E and 1.D shows SEM cross-section of ITO reduced with thin layer of plated Ni), is possible without damaging the solar cell life time, obtain very good specific contact resistance (i.e. < 0.3mΩcm2) with 10 micron of copper and good adhesion (i.e. >2N/mm). Moreover, due to the fast plating condition, it will be shown that the equipment footprint can be interestingly reduced down to less than 18sqm for a 100MW line managing very low amounts of chemical. Due to its unique characteristics, DLD/DLM technique thanks to speed of processing, localized processing, small footprint and reduced chemical consumption, will represents a breakthrough in the market of plating for the solar cell applications. [1] M. Balucani, et al.; “New Selective Processing Technique for Solar Cells”, Energy Procedia (2013) 43, 54-65 Figure 1

Large-scale PV power generation in China: A grid parity and techno-economic analysis

With the limiting supply of fossil fuel and the beneficial impact of technological innovation on renewable energy costs, PV power generation is increasingly considered a promising way to generate renewable power. Under the support of the national emerging industry, China's PV industry has experienced a dramatic development over recent years, catapulting into a vital position in the world PV market. The newly installed PV capacity has led to cost reductions. This paper chooses the methodology of techno-economic evaluation to analyze current market application of residential PV power generation, including grid-connected and off-grid systems. One of the main innovations is choosing five Chinese cities in different areas of solar radiation as research objects, which enables regional differentiation in calculating levelized cost of energy (LCOE). The results show that grid-connected PV systems with 3 kW PV modules can meet the electric demand of a 60–90 m2 residential building. The capacity of off-grid systems are 5–10 kW, which is determined by local solar radiation. By incorporating a learning curve, we forecast that off-grid PV systems for each of the five cities will reach grid parity over the next several decades. The estimation is used to offer policy recommendations for PV market diffusion in China.

Based on the Network Perspective to Identify the Market Leading Enterprise-photovoltaic Industry as an Example

With the economic integration of the world, the correlation between enterprises does not only include their cooperative and competitive relationships, but also involves their mutual relationship in the market. In this paper, a new index, with considering cooperative, competitive as well as market relationships, is proposed to quantify the mutual influence between any two enterprises. Then, the influence index threshold network (IITN) is built from a new perspective of complex network theory. Focusing on empirical research by taking China's PV industry as an example, the leading enterprises are identified by comparison of theirS value in conjunction with nodal degree and ranking of the net profits. The evolution of average degree of hubs and the growth of world PV new installed capacity are the same. In addition, the reasons for some belong to the leading enterprises are explained in detail. The results show that, leading enterprises with core technologies, producing basic products, having complete industrial chain and owning brand products, are likely to have prominent positions during the fierce competition. Finally, some suggestions are made to promote the sustainable development of China's PV market.

Influence of Resource Allocation in PV Technology Development of Japan on the World and Domestic PV Market

SUMMARYThis paper analyzes influence of resource allocation in R&amp;D of solar cells in Japan. First, it estimates solar cell price in Japan in the case resource allocation for R&amp;D of crystalline silicon solar cells was not significantly reduced, but maintained almost constant level. For the projection, it does not use experience curve, but models technological progress, price reduction, of solar cell in Japan with a variable technology knowledge stock by excluding mass production effects. Second, solar cell prices in other countries are estimated based on their market share in the global solar cell production. The estimated solar cell price in Japan under the assumed resource allocation decreases by about 30% compared to the actual one and it, therefore, could be competitive to the estimated solar cell prices in China and Taiwan. In this case, Japan could maintain its top market share in the global solar cell production several years longer. Instead of the Japan's Feed‐in Tariff with subsidy, net‐metering without subsidy is enough for keeping almost the same internal rate of return of residential PV systems for new and existing houses. This paper will be helpful to cost‐effective R&amp;D planning by a modeling and simulation approach.

わが国の太陽光発電技術開発における資源配分の世界および国内市場に対する影響

わが国の太陽光発電技術開発における資源配分の世界および国内市場に対する影響

The Radical Theology of Prometheus Bound; or, on Prometheus' God Problem

Prometheus Bound (PV) is a meditation on God par excellence, second only perhaps to the Bible or Paradise Lost. It is, accordingly, the only extant tragedy from the ancient world featuring the most characters as gods. For this reason it stands out in a genre fixated principally on human suffering, where ‘death carries overwhelmingly more weight than salvation’. Gods, of course, do not suffer like humans: Prometheus, the play's protagonist extraordinaire, may be subject to an eternity of punishment for stealing fire from Zeus, but his pain, real and visceral as it is, differs from ours in that it lacks the potential closure of death. It is perhaps justifiable then to suggest the play's focus is not just the awful things gods are capable of doing to one another (just like humans), but rather the meaning of such behaviour without the ultimate consequence (death). That is, the portrayal of Prometheus suffering and Zeus menacing redounds equally to the type of characters they are as to simply what they are. Whereas the former aspect is of psychological or political interest, the latter is a theological concern. And PV is theological in its implications as much as it is political. Hence the question: What type of theology does it convey? The answer is complex.In the modern world PV has primarily been read for its political allegory—as a meditation on oppression, or martyrdom for the intellectual cause. Eric Havelock's translation and study of the play, to cite an illustrative example, was called The Crucifixion of Intellectual Man (1950). Many critics therefore argue that the play articulates the conflict between Prometheus and Zeus in terms of freedom versus authoritarianism. As Shelley famously wrote in the prologue to his Prometheus Unbound, the imprisoned Prometheus represents ‘the highest perfection of moral and intellectual nature impelled by the purest and the truest motives to the best and noblest ends’ (1820). Marx and Goethe felt similarly. This position aligns Prometheus with the forces of enlightenment and progress over against the brutality of Zeus's authority.

Net CO2 Emissions from World PV from 1992 to 2009

Net CO2 Emissions from World PV from 1992 to 2009

Status of Selective Emitters for p-Type c-Si Solar Cells

Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. Achieving low-cost photovoltaic energy in the coming years will depend on the development of third-generation solar cells. Given the trend towards these Si materials, the most promising selective emitter methods are identified to date. Current industrial monocrystalline Cz Si solar cells based on screen-printing technology for contact formation and homogeneous emitter have an efficiency potential of around 18.4%. Limitations at the rear side by the fully covering Al-BSF can be changed by selective emitter designs allowing a decoupling and separate optimization of the metallised and non-metallised areas. Several selective emitter concepts that are already in industrial mass production or close to it are presented, and their specialties and status concerning cell performance are demonstrated. Key issues that are considered here are the cost-effectiveness, added complexity, additional benefits, reliability and efficiency potential of each selective emitter tech- niques.

Particle Agglutination Method for Poliovirus Identification

In the Global Polio Eradication Initiative, laboratory diagnosis plays a critical role by isolating and identifying PV from the stool samples of acute flaccid paralysis (AFP) cases. In the World Health Organization (WHO) Global Polio Laboratory Network, PV isolation and identification are currently being performed by using cell culture system and real-time RT-PCR, respectively. In the post-eradication era of PV, simple and rapid identification procedures would be helpful for rapid confirmation of polio cases at the national laboratories. In the present study, we will show the procedure of novel PA assay developed for PV identification. This PA assay utilizes interaction of PV receptor (PVR) molecule and virion that is specific and uniform affinity to all the serotypes of PV. The procedure is simple (one step procedure in reaction plates) and rapid (results can be obtained within 2 h of reaction), and the result is visually observed (observation of agglutination of gelatin particles).

Thin-film PV module review: Changing contribution of PV module technologies for meeting volume and product needs

The world PV module market is projected to reach 12 to 25 GWp by 2015, unless politically mandated solar programs are implemented to achieve even larger, more energy significant production volume. To meet projected volumes at a declining cost expected from markets, it is anticipated that thin-film PV module technologies will contribute at growth rates faster than average industry growth rates, and hence contribute 3.5 to 6 GWp toward such anticipated volume. Bolko von Roedern, NREL, USA reports.

PV review: World Solar PV market continues explosive growth

Lead by subsidized grid-connected photovoltaic markets in Japan, Germany and California, USA world photovoltaic production and market growth continued apace in 2004. Paul D. Maycock, PV Energy Systems, Inc., provides an update on the current world PV market situation.

International photovoltaic markets, developments and trends forecast to 2010

1993 world photovoltaic shipments increased only 6.7% from 57.9 MW in 1992 to 60.69 MW in 1993. European shipments increased 1% from 16.4 MW in 1992 to 16.55 MW in 1993. U.S. shipments increased 24.0% to 22.44 MW and Japanese shipments decreased 8% to 17.3 MW. The status of all major PV module producers will be summarized. New entrants in the thin film area include Golden Photon (CdTe), Solar Cells Inc. (CdTe), United Solar Systems (triple-stack amorphous silicon), and BP Solar (CdTe). In the silicon crystal area, plant expansions have been made by Siemens Solar Industries, BP Solar, and Solec. New crystal silicon entrants include Astropower, Texas Instruments, Nukem, and Gallivare. Potential capacity increases by 1996 of 75–100 MW are described. Module performance (efficiency and warranty), and manufacturing costs are summarized and forecast to 2010. In the limit, the sliced silicon product tends to approach profitable prices of $2.00 per watt, while several thin-film options and concentrators can be manufactured with profitable prices less than $1.50 per watt. The world market for PV modules is summarized by market sector and forecast to 2010 under two scenarios—Business as Usual and Accelerated. Under the Business as Usual assumptions, world PV module shipments are forecast to be 195 MW in 2000 and 800 MW in 2010. The Accelerated scenario forecasts world module shipments in 2000 to be 440 MW and 4000 MW in 2010. Module shipments for the last four years have been growing at a rate well below the BAU scenario.

International photovoltaic markets, developments and trends forecast to 2010

The 1993 world shipments increased only 6.7% from 57.9MW in 1992 to 60.69MW in 1993. European shipments increased 1% from 16.4MW in 1992 to 16.55MW in 1993. U..S. shipments increased 24.0% to 22.44MW and Japanese shipments decreased 8% to 17.3MW. The status of all major PV module producers will be summarized. New entrants in the thin film area include: Golden Photon (CdTe), Solar Cells Inc. (CdTe), United Solar Systems (triple-stack amorphous silicon), and B.P. Solar (CdTe). In the silicon crystal area, plant expansions have been made by Siemens Solar Industries, B.P. Solar, and Solec. New crystal silicon entrants include: Astropower, Texas Instruments, Nukem, and Gallivare. Potential capacity increases by 1996 of 75–100MW are described. Module performance (efficiency and warranty), and manufacturing costs will be summarized and forecast to 2010. In the limit, the sliced silicon product tends to approach profitable prices of $2.00 per watt, while several thin-film options and concentrators can be manufactured with profitable prices less than $1.50 per watt. The world market for PV modules is summarized by market sector and forecast to 2010 under two scenarios -- “Business as Usual” and “Accelerated“. Under the Business as Usual assumptions, world PV module shipments are forecast to be 195 MW in 2000 and 800MW in 2010. The Accelerated scenario forecasts world module shipments in 2000 to be 440 MW and 4000 MW in 2010. Module shipments for the last four years have been growing at a rate well below the BAU scenario .