Solar modules are in the spotlight as star performers in supplying cheap clean energy, but it’s the time they spend in the raw elements that will test the long-term viability of PV technology. Arrays all over the world are put under all sorts of strain every day, from high humidity and oscillating temperatures to intermittent coatings of saltwater, dust, sand, hail and snow, not to mention wild winds. Warranties on some modules may extend out to 25 years, but buyers must place a lot of trust in manufacturers to sign up for that.
Much of the responsibility for a solar panel’s longevity relies on the backsheets that protect the PV cells that generate current. If poor-quality materials are used, surfaces can crack or decay, allowing in water or dirt that will push down performance. Revenues at large-scale solar plants in harsh environments can experience acute pain if something as simple as the installed modules’ backsheets start to weather and curl. Just ask developers with projects in India, the Middle East or South-East Asia.
“It’s a much faster decline in high-temperature and high-moisture areas than cold and dry areas,” says Mark Wu, the CEO of Chinese polymer company Cybrid. “In markets like India and Vietnam you have high temperatures and high moisture. We designed KPf to have a better duration in this condition.”
Cybrid Technologies tightened its focus on the solar module backsheet market in 2012 when it refined its KPf Fluro-Skin backsheet technology. Today the company says it commands about 30% of the market in China and 24% in India (60% among the top 10 module manufacturers), and the company is now focusing on the European and South American markets with its transparent KPf backsheet line, launched in 2019.
Bifacial solutions
The past two years have seen dramatic changes in PV module design, including complete encapsulation technology, half-cell variants and bifacial single-glass encapsulation. Cybrid started working with Chinese module-makers on bifacial solutions in 2018, as other suppliers were promoting a double-glass solution. “Several of our competitors supplied them the transparent backsheet but they cannot pass the lab test or the ageing test,” says Wu. “We help them to solve this problem.”
Looking ahead to the task or repairing ageing systems, Cybrid has developed its MoPro program where one of the segments is backsheet onsite repair to tackle the problem of panel degradation and cracking. So far the MoPro technology has been used in China and India to repair about 1GW of modules, Wu says. “MoPro can be used on any module. And frankly, until now, we don’t have any cracks or any claim with our backsheet, so we are repairing [competitors’] backsheet. This product is designed especially for our competitors. When you can take advantage of your competitors’ inferior project, that’s a good situation to be in, isn’t it?”
Wu is hoping the solution will catch on in markets with high labour costs where system owners have to weigh up the options of replacement under warranty or repair. “We are figuring out how we can promote this MoPro concept where we can balance the cost with our services and product.”
Lightweight measures
Cybrid has published about 180 patents and 12.5% of its staff are employed in R&D, so it is always looking to where it can extend its product range in solar. During a trip to the company’s headquarters in Suzhou, an hour’s drive north-west of Shanghai, EcoGeneration was shown an example of Cybrid’s 8kg module, with a polymer front and backsheet behind. Lightweight panels, manufactured without glass or an aluminium frame, cost about 30% more than regular glass panels but are used in applications where standard technology wouldn’t do.
“Lightweight modules don’t compete with general modules,” Wu says. “They are suitable for jobs where the roof is not very strong. Secondly, in some markets where the human resource is very expensive, costs can be reduced because a light panel is easy to carry and install. That means our lightweight module is designed for the special market application, not to compete with the general ones.”
The lightweight module is also easy to recycle, which is a topic that’s becoming more popular as solar installations reach the end of their lives. “The difficulty in recycling is how to separate the parts easily,” says Wu.
The current popular method of recycling is to mangle a module into tiny particles and use a technology of water weight separation to collect the different materials. Cybrid is working with a Japanese firm on a solution that applies techniques developed by the home electronics appliance industry following the introduction of recycling rules in Europe.
“Many electrical home appliance makers developed bonding materials to help these goods to be separated easily,” Wu says. “We learned from this history. We have used the thermal plastic in the encapsulant and pressure sensitive foam tape to replace silicon concealment, so that parts will separate easily to increase the amount that can be recycled.”