thank you Priyan...it is work...done!
Thank you Friyan. This is what I was looking for. Appreciate your help.
PlotLegends -> Placed[LineLegend[c, LegendLabel -> "Solar Concentration"], {Scaled[{0.5, 0.5}], {0.5, 0.5}}]
This might work. You need to change the numbers however.
