Mastervolt Solar ChargeMaster SCM20 PWM [131822000] Violets (February) Cross Stitch Pattern Illustration par Simone Balman. Solar ChargeMaster SCM20 PWM This solar charge regulator based on PWM technology is a great solution to charge your batteries with solar energy. Suitable for both 36 cells panels (in 12V systems) and 72 cells panels (in 24V systems). Its protection against water spray, suitability for high ambient temperature and compatibility with negative grounding, make it the perfect solar regulator for marine and mobile environments. Optionally, a temperature sensor is available. Safe, User Friendly & Flexible The SCM20 PWM is suitable for all types of lead acid batteries in both 12V and 24V. The device features a large display and switchable output with evening night lighting function.