Photovoltaic Arrays And Silicone Encapsulants

Interview conducted by G.P. ThomasOct 10 2012

Eric Peeters, Vice President at Dow Corning, talks to AZoM about Dow Corning’s involvement in an innovative photovoltaic array in Korea.

Could you please provide a brief introduction to the industry that Dow Corning works within and outline the key drivers?

Dow Corning is helping to build a more reliable, powerful and profitable PV plant. We are a trusted technology partner to solar businesses across the value chain, delivering innovative, silicon-based solutions that drive down costs, enhance system performance and help make solar more competitive with traditional forms of energy.

As a supplier of silicone-based materials for more than 70 years, Dow Corning is creating innovative solutions that address the needs of the global PV industry. The intrinsic properties of silicon and silicone materials are a great fit with PV technology:

• Durability to UV exposure
• Wide temperature use range
• Corrosion resistant
• High transparency
• Electrically insulating
• Low Moisture pick-up

We are focused on driving down the cost of PV systems while simultaneously driving up and sustaining a system’s kilowatt per hour (kWh). Together with our partners, we aim to create additional kWh production over the life of the system.

Materials play a role in innovation. Our research and development looks at the following opportunities:

• Using fewer materials (e.g., smaller j-box, thinner wafers, thinner glass, frameless, etc.)
• Using materials at lower cost
• Using materials that increase durability
• Using materials that increase efficiency (e.g., reducing optical losses and electrical losses, manufacturing efficiency, etc.)
• Using materials that enable novel & more efficient designs

Dow Corning is pursuing innovation that will help our customers and, in turn, their customers, to increase the value of their product or investment, at the $/Wp and $/kWh level. Our aim is to continue bringing innovations that help lower the Levelized cost of PV electricity.

Dow Corning has recently teamed up with LG Electronics to install a photovoltaic (PV) array at Seowon University – could you give a brief summary of this? How did Dow Corning come to be involved?

Dow Corning, LG Electronics and Seowon University have signed a memorandum of understanding (MOU) to install a rooftop PV system on the university campus in 2012 for testing and evaluation. The system(s) will employ LG Electronics modules made with Dow Corning silicone encapsulation technology. In addition to providing an in-field demonstration of Dow Corning’s PV encapsulants, the PV system will provide side-by-side performance monitoring of the silicone and ethylene vinyl acetate (EVA) module encapsulants.

Dow Corning has been partnering with industry-leading companies to combine our silicone expertise with their knowledge in module manufacturing. Our collaboration with LG is an example of this. LG shares a culture of innovation and a dedication to advancing the solar industry. Proving the value of silicone encapsulants in field tests is a natural next step in expanding the awareness of this new technology and its benefits, and in bringing it to market reliably and successfully.

What is the power of the initial array? Is there scope to expand this in the future?

The initial array for testing and evaluation will generate 15 kilowatts of power. The larger array that may be installed later will generate up to 1 megawatt of power.

When is the installation planned for?

The planned installation in 2012 of a 15 kilowatt (kW) array is for testing and evaluation. Later, a larger array generating up to 1 MW of power may be installed for potential commercial usage.

The PV array utilises Dow Corning’s silicone encapsulants. Could you explain how encapsulants are utilised in (PV) arrays?

Encapsulants are used to embed the cells into a module. The encapsulant acts as a laminate between the glass cover of a solar module and the glass cover of the solar cells.

What are the physical and chemical properties of silicone that make it a suitable material for encapsulants?

Silicone’s durability, strength and physical transparency make it an ideal material for encapsulants. Silicone encapsulants allow for increased power output and longer module life, reducing the levelized cost of electricity. In addition, silicone can improve and sustain energy output efficiency, including increased kWh energy generation due to its inherent durability against UV degradation. Silicone’s high transparency also allows for a higher watts-peak, yielding higher initial module efficiency.

What are the benefits of using silicone encapsulants over traditional ethylene vinyl acetate (EVA) encapsulants?

The durability and strength of silicone under harsh, long-term exposure to ultra-violet (UV) light, as well as its physical transparency, provide unmatched material advantages over existing solutions—such as EVA—which degrade over time and decrease panel performance.

By significantly reducing performance degradation and sustaining higher panel efficiencies, silicone encapsulants are an ideal solution for key players across the value chain—from module producers to project developers—who are interested in dramatically improving a system’s path to bankability.

In tests, Dow Corning’s silicone encapsulants have achieved higher production rates, improved performance and significantly lower degradation rates for crystalline modules over EVA encapsulants. The tangible results are a lower cost per kilowatt-hour of solar power and a more powerful PV plant.

Does Dow Corning have any more upcoming plans within the solar power sector?

Our goal is to drive down the cost of PV systems while simultaneously driving up the kilowatt per hour (kWh), which is strategic to every player along the value chain. Materials-level PV technologies such as rail bonding for PV panels offer a significant opportunity to achieve these economics faster and with more powerful systems. Dow Corning has leveraged decades of experience in silicone technology to produce a breakthrough silicone-based electrically conductive adhesive (ECA).

Dow Corning fosters innovation, investing in its global team of scientists and engineers and state-of-the-art research facilities to enable better performing, more cost-effective solar cell technologies. We’ve established a global network of solution-driven partnerships, continuously collaborating with customers, research organizations and suppliers.

Dow Corning’s silicone bonding technology, for one, enables the adoption of cost-effective module design (e.g. frameless), helping to significantly reduce a solar system’s total installed cost per watt. This technology has been a proven and trusted solution for many industries for decades, delivering industrial strength and performance. The technology is now emerging as a powerful component to more efficient, high performance PV systems, as a result of partnerships with solar companies.

How do you see solar technology progressing over the next decade?

Despite challenging economic times, the global photovoltaic (PV) market is still growing and becoming more competitive with traditional forms of energy every year. With roughly 70 gigawatts (GW) installed worldwide and another 80 GW estimated by 2016, PV systems—especially large, centralized plants—are increasingly becoming more competitive with traditional energy sources, including fossil fuels.

Recognizing the existing success and future potential of PV, the market is attracting a new and more diverse set of project developers, integrators, utilities, industrial suppliers and investors. Additionally, international governments are subsidizing, incentivizing and protecting the growth of PV and other renewable energy generation in the market, while technology companies are developing new and advanced ways to improve the cost competitiveness of PV.

For module makers in particular, two major trends in panel design are helping lower manufacturing, and in turn, power system costs. The form factors of panels have become larger, with a higher power density, and new frameless models are now reaching market, offering improved aesthetics with less hardware.