Apparently, the battery had drained due to the low sun. It was running when I left at 8pm, but stopped shortly thereafter. This morning, the "load disconnect" LED was red on the sunsaver and the battery measured 12.2V. Disconnecting and reconnecting things didn't help. Swapped batteries with one in the base measuring 12.7V and the station came back up. Took advantage of this opportunity to dump about 2cm of water from the bottom of the battery box.