The dream of manufacturing solar cells and photovoltaic (PV) modules outside of Asia has become increasingly distant. Falling PV module prices, coupled with the fact that Chinese PV module manufacturers are reportedly holding the equivalent of two months' worth of inventory, have fuelled the spiral. Plans for gigawatt-scale PV cell and module production facilities in the U.S. and Europe have been delayed or cancelled altogether, and to make matters worse, Western markets are accumulating inventories of products purchased at twice the price of the current year-end market.

This solar storm is wreaking havoc on the industry, leading to broken glass in modules and more supply chain disruptions. In times like these, it is best to reflect on the words of Albert Einstein, who is reported to have said, "Make things as simple as possible, but not simpler." His argument that an idea should be as coherent as possible without being stripped of its meaning can be applied to the current market for solar PV. Make PV modules as cheap as possible, but not cheaper. Because everything in life has a final price.

Why have PV modules become so cheap?

Solar has become the most affordable and fastest growing energy generation technology. Since 2015, it has outpaced all other renewable and conventional power generation technologies year on year. Part of its popularity stems from price, with each company being extremely price-competitive due to a range of market factors and product improvements. This includes lower notch losses, better module cell encapsulation, less silver, thinner glass, thinner frames, larger modules, cheaper electricity and, most importantly, companies flooding the market with products. Consumers who buy cheaper decentralised solar rooftop PV systems or utility-scale mounting technologies have been rewarded. But over time, especially for larger operators, cracks have appeared.

The price of cheap photovoltaic modules

Over the past decade, PV modules have almost doubled in size, with thinner frames, thinner glass and shorter mounting rails. Half-cut cell modules now typically have three holes in the rear glass, allowing them to withstand considerable PV load weights. This shift occurred in 2017, when 2 mm thick toughened (not fully toughened) glass became cheaper than the gold standard 3.2 mm fully toughened glass for PV modules. Around the same time, utility-scale PV plants began to predominantly use bifacial, double-glazed glass.

Today, almost all large-scale PV plants use double-sided, double-glazed modules with 2 mm glass thickness on both the front and back. However, utility-scale solar power plants installed in recent years have relied on 2 mm double-glazed PV modules with a breakage rate of up to 10 per cent.

Observed cracks can lead to warranty claims and contract disputes, resulting in loss of money, time and good faith. This means that cheap PV not only results in worse outcomes for energy consumers, but also undermines the industry as a whole, affecting PV module and PV tracker suppliers, engineering, product and construction companies, and PV plant owners. This is the case for making PV modules as cheap as possible, but not cheaper.

By Prof Ricardo Rüther (UFSC).

ISES, the International Solar Energy Society, is a member NGO accredited by the United Nations.