deletions | additions       diff --git a/CdTe_photovoltaics_PV_is_the__.tex b/CdTe_photovoltaics_PV_is_the__.tex  index bc5ffd8..8f18588 100644  --- a/CdTe_photovoltaics_PV_is_the__.tex  +++ b/CdTe_photovoltaics_PV_is_the__.tex 
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CdTe photovoltaics (PV) is the only thin film technology with lower costs ($ W<^-1)  than conventional solar cells made of crystalline silicon in multi-kilowatt systems. In August of 2014, First Solar® was able to accomplish a CdTe solar cell efficiency of 21.5\% \cite{firstsolar2015} . while their commercial high volume PV modules have $17.0 \cite{Sinha_2013}.  The theoretical upper bound of efficiency, the Shockley-Queisser (SQ) limit \cite{Shockley_1961} for a PV with a band gap of 1.49 eV (CdTe) under the standard AM1.5G flat-plate solar spectrum \cite{nreal} is 32.2\%. This is relevant considering that other similar thin film PVs such as GaAs have an relative efficiency $ \zeta_{SQ} = \frac{ \zeta_{real} }{ SQ_{limit} } $ \cite{Vossier_2015}, of $ \zeta_{SQ}= \frac{28.8}{33.1} \approx 0.87 $\cite{Yablonovitch_2012}. CdTe research grade PVs have a value of $ \zeta_{SQ}=0.667 $. and commercial PV modules have $ \zeta_{SQ}=\frac{17.0}{32.2}\approx 0.52 $. There is much room for improvement to make this technology more affordable.  This paper discusses the optical and electrical factors that reduce the efficiency of a single junction CdTe PV below the SQ limit and provides recommendations on closing this 9.0-15.2\% gap.  This paper discusses the optical and electrical factors that reduce the efficiency of a single junction CdTe PV below the SQ limit and provides recommendations on closing this 9.0\% gap. We use the index $ \zeta_{SQ} = \frac{ \zeta_{real} }{ SQ_{limit} } $ \cite{Vossier_2015}, efficiency  relative to its own theoretical SQ limit as a measure of this gap.  First Solar CdTe research grade PVs have a value of $ \zeta_{SQ}=0.667 $. This number is relevant when comparing to similar thin film PV such as such as GaAs, $ \zeta_{SQ}= \frac{28.8}{33.1} \approx 0.87 $ \cite{Yablonovitch_2012}. Even more when we consider that commercial high volume PV modules have $ \zeta_{SQ}=\frac{17.0}{32.2}\approx 0.52 $\cite{Sinha_2013}.