-------------------------------------------------------------------------------
   Compute the front/back temperatures of a solar panel.
   Asumes that the front of the panel is illuminated and the back
   has not illumination. 
-------------------------------------------------------------------------------
   Form:
    [tF, tB] = SolarPanelThermal( d )
-------------------------------------------------------------------------------

   ------
   Inputs
   ------
   d               (1,1) Data structure
                         .alpha (1,1) Absorptivity
                         .epsF  (1,1) Front emissivity
                         .epsB  (1,1) Back emissivity
                         .etaP  (1,1) Fraction of flux to power
                         .k     (1,1) Front/back conductivity
                         .s     (1,1) Solar flux

   -------
   Outputs
   -------
   tF              (1,1) Front temperature
   tB              (1,1) Back temperature
   c               (1,1) Final cost

-------------------------------------------------------------------------------