Technical Papers

A total of 2MWp of PV modules were sold on pvXchange’s spot market platform in December 2008. This corresponds to a sharp decrease of 60% when compared to the figures seen in the previous month (5.6MWp). Low trade volumes throughout the years are common on pvXchange; this year, bad weather conditions prevented many new installations, as did the current economic climate that saw many buyers waiting for further price decreases. The closing of long-term contracts has been postponed by many PV companies that are concerned that they will not find customers given the current circumstances. Again, First Solar’s CdTe thin-film modules were the most traded technology item on the pvXchange platform for the month of December.

Electricity has been around for a long time and no doubt will be for the foreseeable future, but it is quickly changing its nature. Owing to evolutions in power electronics, sustainable electricity generation and consumption came to the fore and now it is nigh on impossible for photovoltaics to operate without this technology. This holds true for efficient consumption such as plug-in electric and hybrid vehicles or compact efficient lighting. Power electronics need to be taken into account in relation to grids, for example in novel voltage-source HVDC connections. Photovoltaic energy conversion requires power electronics in order to adapt the floating DC-output to a fixed DC-level and typically further to a grid-compatible AC electricity. These converter (mainly inverter) technologies have evolved considerably over the past few years, in much the same way as has PV cell technology, but in a much less apparent fashion. It is, however, expected and required that the technologies will evolve even further to meet the demands of the future market and the electricity grid to which they will be connected. This article intends to give an overview of the challenges ahead for power electronics in photovoltaic energy conversion.

The PV industry has seen some incredible growth in the last five to eight years. This growth is essential in order to fulfill the challenging targets this industry has set itself to ensure it becomes an economical viable alternative energy source. A negative result of this growth, however, is the inefficient supply chain, where there is a lack of balance between demand and supply. The industry is going from one bottleneck to another. What is the impact of such inefficiencies on the supplier/manufacturer relationship? In this article, we collect information from short interviews of a number of fab managers in the wafer, cell and module domain, and try to answer this question.

Owing to the huge demand for photovoltaic products, the market is still very attractive for investments in production facilities. Nevertheless, the increasing number of competing photovoltaic manufacturers and the decrease in governmental subsidies require substantial and continuous cost reductions. Whilst existing facilities can save costs by enhancing cell efficiency, optimizing production processes or reducing material costs and other resources, for new manufacturing sites there is a great potential in making efficient use of economies of scale. This also holds true - to some extent – for expanding existing fabs. This paper presents the logistics behind and the benefits of implementing economy of scale in a PV manufacturing facility.

Materials innovation in solar photovoltaic manufacturing has long played a key role in efforts to raise cell and module conversion efficiencies, improve overall device performance and reliability, and lower the overall cost per manufactured watt. Research and development in areas such as ultrathin-silicon wafering and replacement films for thin-film PV transparent conductive oxides often garner much of the industry’s attention. But a wide range of emerging technologies could provide crystalline-silicon and thin-film cell and module manufacturers the kinds of materials solutions that will accelerate their attempts to reach competitive levelized cost of energy metrics and ultimately attain their goal of achieving grid parity with conventional energy sources – as well as open up lucrative market opportunities for the materials suppliers.

Laser-based tools have become increasingly visible within R&D labs, pilot production lines, and as the preferred technology used by many turnkey suppliers. As equipment types however, relatively little is known about the differences in the laser-based tools used for solar applications within each of the c-Si and thin-film segments. This paper explains the key components of a laser-based tool, and how they are adapting to meet the demands from next-generation production line equipment required by the solar industry.

The rapid expansion of high volume manufacturing to meet growing demand in recent years has highlighted the development of increasingly higher throughput machines, especially in the critical bottleneck process of module assembly, specifically characterised by tabbing and stringing steps. Significant productivity improvements have come about with the development of integrated, highly-automated tabber and stringers from a range of equipment vendors. However, module assembly remains the most expensive step in conventional c-Si cell production. Equipment suppliers are also challenged to meet the evolving demands of processing thinner wafers and to address overall production cost reduction strategies while meeting yield/throughput goals that are seen as a significant enabler of reducing the cost per watt.

News of credit crunch woes filtering down the lines over the past few months has instilled a sense of frugality in all industry sectors. While the credit crisis has indeed affected the PV industry, German banks, investors and creditors have claimed that the financing of small PV systems in the private sector seems not to be endangered. Downstream players are still optimistic, but the upstream sector is anticipating severe damage as a result of the economic situation. An interactive workshop-style discussion, hosted by the German market researcher EuPD Research and its consulting division 360Consult, invited top-level executives to contribute their experiences of the current financial situation, as discussed in this paper.

The U.S. residential solar market is poised for growth. For solar companies seeking to capitalize on the growth potential of this market, the keys to success will be sales volume and operating efficiency. Solar employee purchase programs (solar EPPs), which have been initiated by companies as diverse as SunPower, REC Solar, and SolarCity, represent a new and potentially important channel for increasing sales and improving sales efficiency. Driving these programs are increasing corporate sustainability initiatives and growth in voluntary employee benefit offerings, especially employee purchase programs and green benefits. This article provides an introduction to solar employee purchase programs, analysis of the business ecosystem, and discussion of an example program. It is based on the industry’s first report to identify and analyze this emerging trend, which was published by AltaTerra Research in November 2008 [1].

In any solar cell process, the metallization step is critical as it often sets conditions and limitations for the other process steps. The main metallization technique used today in Si solar cell production is screen-printing of metallic pastes, namely Ag pastes for the front side, Al pastes for most of the rear side, and Ag or Ag-Al pastes for the solder pads at the rear. While these techniques are clearly robust and convenient, they have limitations. Therefore alternatives are being investigated. A technique that is presently finding its way into production is two-step metallization with Ag plating. Another more radical approach is to avoid printing altogether, instead using some kind of ablation followed by plating. For the rear, the full Al-BSF is being replaced by dielectric passivation and local Al-alloyed contacts. Back-contacted cells are increasingly being introduced in production, and they pose very specific challenges to metallization. For the sustainability of Si photovoltaics, it is crucial that the future metallization solutions only make use of abundantly available and non-toxic materials.