PV Panels: Photovoltaic (PV) Panel Waste Volumes-7

PV panels, as noted in previous sections, create unique waste management challenges along with projections of increasing waste streams. Outside the EU, end-of-life treatment requirements for PV panels worldwide are determined by waste regulations applied to any waste in general rather than specifically allocated to PV. Waste regulations are based on the classification of waste. This classification is shaped according to waste composition, particularly in relation to any components considered hazardous.

Component Trends

Various components of major PV panel technologies affect material and waste characterization as well as the economics of treatment pathways. The design of silicon-based and thin-film panels varies by affecting their composition accordingly. A typical crystalline PV panel with an aluminium frame and 60 cells has a peak power capacity of 270 watts (Wp) and weighs 18.6 kilograms (kg). For a standard CdTe panel, an average of 110 Wp is acceptable for 12 kg weight. A CIGS panel typically has a capacity of 160 Wp and weighs 20 kg. Research conducted on PV components concluded that progress in material savings and panel efficiency will lead to a reduction in material use per unit of power and potentially in the use of hazardous substances. On this basis, Figure 10 compares the materials used for major PV panel technologies between 2014 and 2030. [caption id="attachment_129692" align="aligncenter"] Figure 1. Projection through 2030 in terms of the percentage of total panel mass of materials used for PV panel technologies.[/caption]

Crystalline Silicon (c-Si PV panels) PV Panels

By weight, typical c-Si PV panels today contain approximately 76% glass (panel surface), 10% polymer (encapsulant and back sheet foil), 8% aluminium (mostly frame), 5% silicon (solar cells), 1% copper (interconnects) and less than 0.1% silver (contact lines) and other metals (mostly tin and lead). Industry trend studies such as the International Photovoltaic Technology Roadmap (ITRPV) suggest that new process technologies will predominate by promoting more complex and diverse cell structures as well as thinner and more flexible panels. These will also require new interconnection and encapsulation techniques. For example, bifacial cell concepts offer high efficiency in dual-glass panels consisting of two glass panels each two millimetres thick. A reduction of up to 20% in the encapsulant layer is possible thanks to thinner panels. Cells with back-contact and metal-wrap technology that reduce transmission and electrical losses (known as hetero-junction concept cells) are also expected to gain equal market share. By 2030, the glass content of c-Si panels is expected to increase to a total of 80%, corresponding to 4% of panel weight. Main material savings will include a reduction in silicon from 5% to 3%, a 1% reduction in aluminium and a very slight 0.01% reduction in other metals. Specific silver consumption is expected to decrease further through improved metallization processes and replacements with copper or nickel/copper layers. In today's market, the most efficient panels with interdigitated back contacts with back connections have shown approximately 21% efficiency. Hetero-junction technologies have reached 19%. The average efficiency of a c-Si panel has grown at approximately 0.3% over the past decade. In our next article, we will continue with a-Si PV panels, wishing you healthy days.   Dr. Cemil Koyunoğlu Dokuz Eylül University Faculty of Engineering Department of Mechanical Engineering