One question I had, was if there was an exception to Dr Barnett's analysis where low efficiency PV panels are used as the roofing material. Dr Barnett replied that this analysis still applied and the current approach of high cost mounting for solar panels using tempered glass were not the correct approach. But even where low-cost techniques are used to apply a solar coating to roof material, efficiency still counts: the higher the efficiency, the greater the cost effectiveness. He is researching solar cells built on a steel plate, so that this could be used as a low-cost roof.
However, in my view, if it is the area available for the PV panels is not limited and the substrate material is free (because the roof of a building has to be covered with something anyway and is not being used for anything else), than "efficiency" in terms of light converted to electricity is less important. If using a less efficient coating lowers the cost per Watt, it does not matter how much area this uses, as long as it is cost-effective to install.
If using solar panels as building roofs is to be feasible, then what will be more important is not the efficiency of the solar coating, but the cost and compatibility of roofing and re-roofing buildings. As an example, research is needed into what the panels should look like. Some panels will need to be disguised as exiting roofing material, such as tiles and slate. Other cases the panels will need to be conspicuous to give an environmentally responsible look.
The levelized cost of energy (LCOE) is used to compare different energy generation technologies or systems. The relatively high LCOE of photovoltaics (PV) can be an obstacle to adopting it as a significant electricity source for terrestrial applications. In a conventional PV system, the cost of the module contributes approximately half of the expense and the other costs are together summarized as balance of system (BOS). A large portion of the BOS is not related to the peak power of the system, but can be either proportional to or independent of the total installation area. Across different PV systems with the same installation area, this part of BOS ($/W) is directly dependent on the module efficiency. Therefore, the LCOE is affected by the module efficiency even if the module price ($/W) remains the same. In this paper, the LCOE across PV systems with equal installation areas but with modules of different efficiencies installed with fixed tilt, 1-axis tracking or 2-axis tracking are compared. It is concluded that at a given module price in $/W, more efficient PV modules lead to lower LCOE systems. Two examples of new high efficiency solar cell modules; thin crystalline silicon (20+%) and tandem solar cells on silicon (30+%) will be presented.
Allen Barnett joined the School of Photovoltaics and Renewable Energy Engineering, The University of New South Wales, Sydney NSW 2057 Australia as Professor of Advanced Photovoltaics in September 2011. At UNSW his research is focused on new high efficiency solar cell modules; thin crystalline silicon (20+%) and tandem solar cells on silicon (30+%). He joined the University of Delaware in 1976 as Director of the Institute of Energy Conversion and Professor of Electrical Engineering. He left UD in 1993 to devote full time to AstroPower, Inc, which became the largest independent solar cell manufacturer and the 4th largest in the World. He returned ot UD in 2003 and was Executive Director, Solar Power Program; Research Professor, Department of Electrical and Computer Engineering; and Senior Policy Fellow, Center for Energy and Environmental Policy at the University of Delaware, Newark Delaware. Barnett has supervised 26 Ph.D. theses including 7 Ph.D.s and 3 M.S. degrees in 2011.
Barnett received his M.S. and B.S. in Electrical Engineering from the University of Illinois, and his Ph. D. in Electrical Engineering from Carnegie-Mellon University. He is a Fellow of the Institute of Electrical and Electronic Engineers (IEEE). He received the IEEE William R. Cherry Award for outstanding contributions to the advancement of photovoltaic science and technology and the Karl W. BAer Solar Energy Medal of Merit. He is on committees for the two largest photovoltaic conferences. He has more than 280 publications, 28 U.S. patents, and 7 R&D 100 Awards for new industrial products. He actively consults for government agencies, institutional investors, and private companies. He was named one of aThe 50 Most Influential Delawareans (State of Delaware) of the Past 50 Yearsa in 2012.