Ideal for residential solar thermal systems, the SOLAR PM2 from Grundfos is an energy-optimized, high-efficiency circulator that efficiently operates at flow rates between 0.5 gpm and 40 gpm with head rates up to 47 ft. high - typical ranges for residential and light commercial forced-circulation solar systems. The SOLAR class circulators integrate with most solar controllers via a PWM interface to regulate flow and optimize heat output based on a system’s energy production (e.g., less flow at higher temperatures).