Interview: Rajaram Pai, DuPont Photovoltaics and Advanced Materials

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Rajaram Pai is business leader for DuPont Electronics and Imaging (E&I) South Asia and marketing manager for DuPont Photovoltaic and Advanced Materials (PVAM), South Asia and ASEAN. With 12 years in the PV industry, Pai’s expertise includes areas such as the economics of solar systems and PV cell efficiency. pv magazine recently spoke to Pai about solar technology trends, DuPont’s innovations, and the company’s role in India.

By 2035, global demand for energy will increase by 36%. How is DuPont meeting rising demand for secure, environmentally sustainable, and affordable energy solutions throughout the world?

DuPont Photovoltaic Solutions partners with stakeholders in firstly creating awareness around the need for quality while designing PV solutions, alongside enhancing solar panel efficiencies and improving lifetime performance. We have utilised real field data and rigorous statistical analysis to develop innovative new materials, help lead change in global quality standards and drive specifications based on proven performance over time.

In India, as PV is relatively new and expanding rapidly, DuPont works along with industry stakeholders to advise on new technological advancements, quality standards in PV, and educate on the importance and correlation of materials to power generation, system lifetimes and safety, and overall levelised cost of electricity (LCOE).

The company has more than 150 innovations to its credit, including Solamet metallisation paste and Tedlar PVF film, which has been vigorously tested in the field for more than 30 years. Where do these products stand in India?

All these products are well known to Indian PV customers. Besides these, we are also supplying advance polymers for applications such as junction boxes, tracker bearings, and mounting structures. While the India PV market does possess some unique challenges, and is one of the most cost-conscious markets, the increasing adoption of these products is driven by their strong value proposition (efficiency, reliability) coupled with strong local sales and technical support, which provide unique benefits to the customers (better product performance, less warranty claims, lower LCOE).

Please tell us about the transparent backsheet that DuPont recently introduced for bifacial modules.

Bifacial technology has a promising future with the ability to increase total power output of the module. Today, the bifacial technology is offered through glass-glass module structures, which have challenges including higher weight (increases structure and labor cost), breakage of glass (thinner and weaker as compared to glass used in glass-backsheet structure), moisture entrapment and subsequent power degradation, etc. To respond to this, DuPont launched the Clear DuPont Tedlar PVF film for transparent backsheet as a better solution for the bifacial modules than the current glass-glass structure.

While transparent backsheets based on Clear DuPont Tedlar PVF film have been in use for more than 20 years (primarily for building-integrated photovoltaics applications), DuPont recently launched an advanced version of this backsheet to cater to the bifacial technology. Though the downstream players from India have appreciated the product, we believe that the Indian market is still few years away from adopting bifacial technology for large utility-scale projects.

DuPont has inspected over 4 million solar panels in 275 installations across the world to understand ageing and degradation of modules in the field. What’s the long-term impact of poor quality?

The results of this panel assessment show strong dependence of module performance on materials (cells and backsheets) and climate (higher defect rates in arid regions). As an example, the consequence of frequent changes in backsheet materials by module suppliers such as Polyamide (~56% defect rate), Polyvinylidene fluoride or polyvinylidene difluoride (~30% defect rate) and Polyethylene terephthalate (~22% defect rates) have led to not only safety issues (current leakage, arcing due to short circuit) but also power loss (ground faults, inverter tripping, moisture ingress). This has resulted in significant financial loss for both module suppliers and project owners.

Focusing on just immediate cost/watt-peak is very much a short-term approach. Instead, we focus on a longer-term view, and think in terms of anticipated cost/kilowatt hour over the system’s expected lifetime of 25+ years. Shorter system lifetime, a decrease in five years or so, is anticipated to increase LCOE and inefficiency by over 30%. Conversely, by extending the system’s lifetime and performance by five years can help decrease the LCOE by 20%.

Poor quality solar panels are a big concern in India. What is the solution?

In India, our field studies have revealed significant variations at installations where attention to technical detail ahead of commercial operation date and at those where requisite O&M practices have not been pursued. While lower prices have led to increased solar adoption in the country, the accepted quality standards should be enhanced for modules beyond those warranties specified in Bureau of Indian Standards and International Electrotechnical Commission (IEC).

Intensive studies by the Indian Institute of Technology Bombay and DuPont have indicated the shortfalls in performance and safety have a correlation to compromises in materials and leniency in manufacturing processes. To strengthen the infrastructure for filtering out substandard modules, more affordable and reliable testing facilities can be instituted across the country.

What kind of problems does India’s solar domestic manufacturing sector face?

Lack of local supply chain (manufacturing), higher capital costs, restricted access to new technologies, and research and development and scale (as investors haven’t had success in past).

What are the main solar technology trends in East and South Asia?

China has certainly taken a lead in the adoption of high-efficiency module technologies (mono, mono-perc, n-type, etc.) with government programs such as Top Runner driving demand. These technologies are gaining presence in some other Asian countries and are expected to rapidly gain share in the next few years. From an application perspective, floating PV is gaining traction in all major solar power producing countries in Asia.