A Solar Controller
for
A Solar Collector

On November 8, 2008 this little differential controller was created. It was designed to be a low cost, rugged-alternative to other controllers. The "Little Giant" can regulate either AC or DC pumps for solar hot water or solar heating systems. I called it the "Little Giant" because it can handle pump demands up to 300 watts. A single differential potentiometer integrates the pump on and pump off settings with one adjustment. The "Little Giant" may stand on it's own or it may be connected to meters that monitor temperature. Improvements made on the Little Giant led to the development of the AC/DC controllers with monitors. 

The AC-DC Differential Controller  is based on the Little Giant concept with a few improvements in the differential adjustment and protection with respect to polarity. This AC/DC controller regulates AC or DC pumps in response to differential temperature just like the Little Giant.
A tiny 12 VDC wall transformer supplies controller power when an AC pump is regulated.

When PV power is used to drive a DC pump the same PV power may be used to directly power the controller a battery backup is recommended to stabilize the voltage fluctuations that occur when a pump turns on and off.  If a battery backup is not used with a PV system a PV Differential Controller should be used. 

The AC/DC controller is rugged and dependable and it consumes less than one watt  per hour of energy yet it can drive pumps that consume up to 300 Watts per hour.. Two temperature monitors continuously monitor and display both collector and storage temperatures. A differential potentiometer is used to adjust the differential. 

For more information about the AC/DC controller click on the illustration to the left.

For other differential controller options  try   choosing a controller

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