05 June 2012
As the price of copper approaches a five-year high on the futures market, rising 13% from the start of 2012 alone, the solar energy market is beginning to take notice as everything from cabling to solar panels utilize the popular metal.
Additionally, with the electric car and smart grid markets only increasing the global demand for copper, the price shows no signs of falling anytime soon. Furthermore, the tremendous growth within the utility-scale PV market only amplifies the challenge. The number of completed utility-scale PV projects increased 18% in 2011, according to GTM Research’s 2011 Year-In-Review US Solar Market Insight Report. This dramatic increase shows no signs of slowing down, with a reported 9GW of projects in the US with signed utility power purchase agreements (PPAs) to be completed over the next 5 years and 30GW of early–stage projects seeking permits, interconnection agreements, PPAs and financing.
Combine the size of these projects and the large amount of copper used within them, with steadily increasing copper prices and it becomes an issue that the industry cannot afford to overlook. In order to cope with the rising prices and reduce future costs, solar technology manufacturers and PV system developers have been looking for ways to limit the use of copper in projects. Since PV inverters typically account for 9% of PV system costs and most require a significant amount of copper cables, it is a logical first place to start when trying to engineer a solution.
Inverter design and technologies
In order to cope with the rising costs many inverter manufacturers are looking at designs that limit the amount of copper used throughout a PV system, which in turn can help to drive down balance of system (BOS) costs for their customers.
Some of these designs involve substituting aluminum for copper while other manufacturers have engineered solutions that allow the inverter to be placed farther away from the PV panels without increasing the amount of copper cabling required. Regardless of conductor material, additional savings can be achieved with a bipolar inverter. Previously when trying to determine the type of inverter best suited for a specific PV project, key deciding factors included the system size, the importance of efficiency, the type of modules being used and other integrator preferences.
Now, with the cost being the primary driving factor a technology that results in lowered costs without negatively affecting performance must be considered. For example, with the help of new innovative tools and technologies, conductor costs for bipolar inverters can be reduced by up to half. This technology does so by enabling the connection of the neutrals of the arrays together without returning to the inverter reducing the long-length and large-diameter wires, reducing not only copper usage, but labor costs associated with installation. It can also be used for PV inverters placed up to 2000 feet (609.6 m) away from the PV panels, significantly reducing the installation costs and DC cable losses.
Working at higher DC array voltages has become a top priority in photovoltaic system design as it means the inverter requires less conductive material resulting in lower costs and, in some cases, improved system efficiency. With this new technology, bipolar inverters are able to reduce conductor cost and improve system efficiency while remaining under 600VDC.
Given that the price of copper and the growth of the solar industry show no signs of slowing down, it is clear that to stay competitive both manufactures and project developers need to explore new innovative options for reducing project costs. Aside from the inverter there are various other ways to reduce costs associated with copper and as a result the most successful companies in the industry will continue to push forward with unique and innovative design solutions that reduce the amount of copper cables in a PV system, thereby reducing their exposure to this volatile commodity.
Written by Steve Levy, Vice President of Sales, Advanced Energy.