A force-commutated SCR makes a novel Solid State Switch in a solar charge regulator control. Prior art includes relay and transistor switches, but an SCR switch in this type of DC application may be new to the world (normally SCRs are applied in line-commutated AC applications). Advantages include robustness and the requirement of only one conductive device that performs (3) functions: switch, latch and reverse polarity diode (reverse blocking thyristor). The main SCR conducts the charging current from the solar panel to the battery while a 2nd commutation SCR performs the function of commutating (turning off) the main SCR current at the end of the conduction period. All circuitry consists of readily available discrete components. Note that this is old technology and may not be the best or cheapest solar charge control solution, but it makes a great, mind-expanding tech school lab experiment.
This circuit is applied in fashion similar to
