World solar PV capacity in April 2017 grew to 306GWp. It is expected to rise further to 4,500 GW by 2050. While solar waste isn’t a critical concern yet, the number of panels now being installed on residential and commercial rooftops and in ground-mounted community- and utility-scale projects suggests that starting planning ahead today could prevent a plethora of problems over the next several decades.
Given an average solar system lifetime of 30 years, large amounts of annual waste are anticipated by the early 2030s. Also, solar PV systems waste by the 2050s (5.5-6 million tonnes) shall almost match the mass contained in new installations (6.7 million tonnes). The world’s total annual electrical and electronic waste (e-waste) reached a record of 41.8 million metric tonnes in 2014. By 2050, the PV panel waste added annually could exceed 10% of the record global e-waste added in 2014.
Solar photovoltaic panels have an impressive lifespan. Manufacturers provide PV modules warranties for 25 years, though many systems installed in the 1980s are still going strong today. At some point, though, even the hardiest of these panels will fail. And, as they are composed of both valuable precious metals and toxic materials (along with easily recyclable aluminum and glass), the panels will require careful end-of-life handling, an issue the industry is only just beginning to consider.
PV modules for example contain substances such as glass, aluminium and semiconductor materials up to 85% of their weight can successfully be recovered and reused.
At present, only the European Union (EU) has adopted PV-specific waste regulations. Most countries around the world classify PV panels as general or industrial waste. In limited cases, such as in Japan or the US, general waste regulations may include panel testing for hazardous material content as well as prescription or prohibition of specific shipment, treatment, recycling and disposal pathways. The EU, however, has pioneered PV electronic waste (e-waste) regulations, which cover PV-specific collection, recovery and recycling targets.
SolarWorld has operated a pilot scheme for recycling PV since 2003, where plastic components are removed first by a thermal process before the silicon wafer is recovered through etching. SolarWorld also recovers silicon from broken solar cells. SolarWorld re-uses the silicon granules, and everything else is either sold or sent for recycling/disposal.
First Solar has also developed a process for recycling CdTe thin-film modules. CdTe represents a synthesis of two extremely toxic chemicals. The process has been scaled to full production at each of its manufacturing facilities in the US.
Solar racks and foundations can be made up of aluminum (very long life span) or steel. The life span of steel piles can be prolonged over 40 years with the help of zinc coatings. This is one of the most common methods for increasing pile life against atmospheric and soil corrosions. Zinc is very durable and provides a sacrificial anode. Even when damaged, the zinc corrodes before the steel is attacked because it is higher on the galvanic scale. Pile shape also affects corrosion. Compared to H-piles, or Schletter piles, round piles generally corrode slower. The interior of the pipe does not come into contact with the exterior soil, which has significant oxygen content. The oxygen contained in the soil on the inside of the pipe is consumed fairly quickly and corrosion then slows. In contrast, all surfaces of the Schletter, or H-piles are exposed to the aggressive soils.
Copper that is found in the wiring is a highly valuable material that can be recycled at scrap metal facilities.
Yet, PV recycling is not economically viable nowdays. There aren’t enough places to recycle old solar panels, and there aren’t enough defunct solar panels to make recycling them economically attractive yet. Local policies are required to make the decommissioning process of solar PV systems economically viable and to open up opportunities for new sustainable businesses and practices.