This graph indicates how well the heated water from the panels distributes across the storage tanks. Tank B is one of the two middle tanks and is near the edge of the panel plumbing. The bottom temperatures were pretty even the whole time, which is expected since the heat takes a long time to conduct down through the pipes. During the day, the close end of the top of the tank is roughly 10 degrees warmer than the far end, but as soon as the panels stopped introducing heat to the system, the close end cooled down to roughly the same temperature. Data was also taken from the two ends of the system and are pretty close to the results in this graph.