PVCOMMERCIAL
Parallel design economics
Paul Grana and Michael Lamb, VP of Business Development at eIQ Energy discusses the economics of parallel system design and the potential improvements that can be achieved in commercial scale solar plants.
T
he solar photovoltaic (PV) industry has enjoyed spectacular growth for the last decade. This has been due, in large part, to dramatic reductions in the installed cost of solar systems. Several factors have driven cost reductions: improved manufacturing efficiency, scale economies in purchasing, and improved installation labour efficiency.
However, despite the significant improvement in solar PV economics, further cost reductions are required to achieve grid parity. According to McKinsey’s report on the economics of solar power,1
There is some precedent for this. Solyndra is one example: by redesigning their module (structural frame with smaller racking components, cylindrical PV cells for reduced wind load, and passive ‘tracking’ and rooftop sunlight reflection), they reduce the amount of labour, racking, and wiring required to assemble a commercial rooftop PV system. In this paper, we will describe another approach to design for cost reduction: the use of parallel system wiring rather than series.
installed system costs need to be under $4/watt to reach grid parity in California, and under $3/watt for grid parity in Texas. To reach these goals, system designers are increasingly looking at system design innovations for cost reductions.
This article will outline the cost reducing nature of a parallel system architecture, starting with an overview of series and parallel wiring schemes. We will then look at a reference system design, including a detailed electrical bill of materials. Finally, we will compare the difference in hardware and labour requirements, and therefore system
1. “The Economics of Solar Power” by Peter Lorenz, Dickon Pinner, and Thomas Seitz, published in The McKinsey Quarterly, June 2008
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Image 1: Illustrative schematic of series wiring (represents 6.0kW of First Solar modules): Note that the 80 modules are wired in series, which requires 16 five-module strings
www.solar-pv-management.com Issue V 2010
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