This work is concerned with temperature PID control with gain scheduling in a solar power plant. The control solution is driven by the characteristics of the process and the scheduling variable is obtained directly from the accessible disturbances and reference value. The PID parameters are tuned for an intermediate operating point and then extrapolated for all operating range based on the physics of the plant. The known dependency with the flow guarantees that the time constants and incremental gain varies monotonically with the operating point.