In CSP systems, the solar multiple is a way to specify the solar field area as a multiple of the power cycle nameplate capacity. By definition a solar multiple of one is the solar field area required under reference conditions to deliver sufficient thermal energy to the power cycle to drive it at its nameplate capacity.
For a detailed discussion of the solar multiple, please see the topic "Solar Multiple" in SAM's Help system, under "Parabolic Trough."
Best regards,
Paul.