Since the dawn of solar-generated power, industry insiders have explored new ways to drive costs out of the design …
John Baxter, Swagelok Company, Solon, OH, USA
Since the dawn of solar-generated power, industry insiders have explored new ways to drive costs out of the design, manufacture, and operation of solar cells. Today, the industry is inching closer to reducing the cost/kilowatt-hour (kWh) associated with solar-generated power to levels that are more in line with those found in the traditional generation of electricity. To reach this goal, the industry must eliminate redundancies and inefficiencies that add to the complexity of generating PV power, not to mention the cost.
Much can be said for addressing standards in the quest for reducing costs. Standards may add costs to processes due to the extra steps they require to ensure quality. The alternative is to utilize more relaxed or unqualified practices, components, and systems. This can be a risky choice, and quality may suffer.
Arguably, the additional steps required by standards help to save money in the long run by contributing to the longevity and successful operation of a component or system. However, when unnecessary steps are applied to a process – whether for manufacturing components or developing systems – the cost-benefit equation doesn’t add up. Therefore, it is important to implement standards that are appropriate to the process. The SEMI North America PV Standards Committee is currently addressing this challenge by defining appropriate purity levels for common bulk gases and chemicals. Similarly, the industry needs to address production methods for stainless steel components used in these systems.
For example, the PV industry has traditionally looked to the semiconductor industry for appropriate requirements, which are often in the ultrahigh-purity (UHP) range. In many cases, however, components rated for UHP semiconductor processing are over specified for PV production needs. UHP components undergo additional processing steps – often in cleaning, testing, and packaging – that are not required to ensure their reliable operation in a PV process. Each extra step adds cost to the component.
For example, surface finish specifications for UHP components require minimal surface flaws and inclusions within a component. Smoother surfaces reduce the total wetted surface area of the component, which helps to improve purging and moisture removal. These characteristics help to maintain cleanliness in both semiconductor and PV processes. However, PV production systems are much more tolerant of small amounts of possible contamination that may result from less polished surfaces. The extra surface preparation steps required for UHP components are not needed for PV components. The key, then, is to develop a processing standard that is specifically designed for PV components. Swagelok Company has taken a first step toward reaching this type of standard by issuing a new “Photovoltaic Process Specification” that matches cleaning, testing, packaging, and assembly steps for stainless steel components to PV industry needs. The specification matches cleaning protocols to the contamination sensitivity of materials and line widths used in PV systems. It substitutes advanced surface chemistry analysis with a less complex critical pitting temperature (CPT) test to verify the corrosion resistance of components. The specification also moves system assembly to a controlled environment rather than a clean room, which is required for assembling UHP systems.
The PV industry has an opportunity to drive unnecessary costs out of the component manufacturing equation by developing industry-specific standards. Ultimately, such specifications will help suppliers reduce manufacturing costs for PV components compared to the costs of producing UHP components. The resulting savings may be passed on down the supply chain, reducing the total cost of solar.
John Baxter is manager, products and technology at Swagelok Company, Solon, OH USA; email@example.com.