Scott, I would confirm you voltage coming into the control and then measure the voltage at relay 1 terminals 17 & 18 with the solar pump disconnected. If you measure 120v than the pump could be causing the voltage drop. If you still measure a voltage drop you may want to check the ground or neutral of the incoming power to make sure you have good connections. You can always call Caleffi tech support to discuss.
Scott, I would confirm you voltage coming into the control and then measure the voltage at relay 1 terminals 17 & 18 with the solar pump disconnected. If you measure 120v than the pump could be causing the voltage drop. If you still measure a voltage drop you may want to check the ground or neutral of the incoming power to make sure you have good connections. You can always call Caleffi tech support to discuss.