Silicon photovoltaic: Where is it heading?
(Picture credit: EMA)
With solar energy a viable clean energy option for the region, Professor Martin Green at the PV Asia Pacific Conference provided a forecast of some of the key price and performance trends of silicon photovoltaic over the next few years.
Silicon as the base material for photovoltaic is hard to dislodge as the average selling price is low compared with other materials. According to market analyst firms, the manufacturing cost using silicon has been decreasing over the years and is expected to reach a price range of around US$30/kg by end-2012. This can be expected to go even lower, reaching under US$20/kg over the next few years.
One major trend is towards the manufacturing of larger silicon ingots, which is more cost-efficient. The size of ingots has grown from 270kg to 420kg over the last few years. According to the International Technology Roadmap for Photovoltaic, this will reach around 600kg in 2015, 800kg in 2017, to over 1,000kg in 2020. Furthermore, damages to an ingot during the manufacturing process normally occur at the edges. With a larger ingot, the fraction of the edges versus the total volume will decrease, resulting in better yields.
The efficiency of the silicon cell has improved from 15 percent in the 1970s to around 25 percent currently. Moving forward, one potential research direction towards achieving higher efficiency limits (estimated at over 73 percent using thermodynamics modelling) is to overlay a silicon-based cell stack with other high-performance thin-film cell stacks.
The estimated efficiency for a two-layer tandem overlay is around 44 percent. The efficiency potential may reach 68 percent for a six-layer tandem overlay.