Fitting and setting up

Please take some time to read these instructions Before making connections to the board.



This controller unit is designed to give complete and adaptable control for a Diy type Solar hot water system as described in detail on our website  The wide range of adjustments on this controller should also make it adaptable for many other types of homebuilt solar hot water systems. The only limitation will be the size of the pump used. Too large a pump may cause damage to the circuit board by overheating of the output transistor. To use a large or heavy duty pump it may be necessary to use an external relay and power supply.


1. Difference Temperature ( DIFF ) There are two temperature probes used in this system. One is attached to the top of the solar panel near to the water exit pipe ( the hottest part of the system ) and will be called the ( Panel Temp ) The other probe will be called the ( Tank Temp ) and will be situated some where on the hot water cylinder. 20 cm down from the top of the cylinder will be a good place to situate the tank temp probe, but there is no hard and fast rule for this and you may wish to experiment with this position. The control marked ( DIFF ) that goes from approx 1 to 20 degrees C is adjusted so that the pump only pumps when the panel is hotter than the tank by this amount. E,G.  With this ( DIFF ) control is set to say 10C the pump will only start to pump when the panel temp is hotter than the tank temp by 10C. This control turned fully clockwise will put the controller in AUTO mode. AUTO mode will be described in more detail later.  Setting the ( DIFF ) on too low a setting may let the system  cool down the water in the cylinder. A setting of about 10C to 15C works well in many cases.

2. On Time ( ON TIME ) This control determines how long the pump will pump for each cycle and is adjustable 1 to 20 seconds approximately. 1 to 8 seconds works well depending on the setup.

3. Off time ( OFF TIME )  This control determines how long the pump stays off each cycle. This delay 1 to 20 seconds is added to the 10 seconds cycle time built in to the controller.

AUTO . With the ( DIFF ) control fully clockwise the controller goes into Auto mode. When in this mode the ON TIME increases as the temperature  difference increases. This AUTO delay can be added too by increasing the on time and off time controls still further.

PUMP ON LIGHT This green light comes on to indicate that the pump is pumping.

TOO COLD LIGHT This red light flashes once every 15 minutes when the panel temp probe is below about 15C and the system goes into low power standby mode.

BATTERY LOW LIGHT This red light flashes once every 15 minutes when the system battery drops below 12v and indicates a problem with the battery that needs attention.  This also puts the system into low power standby mode.

LCD DISPLAY The controller works on a continuous cycle:  Displaying _ Battery voltage _ Panel temperature _ Tank temperature then do the pump ON TIME then OFF TIME then start again. The LCD displays in sequence these various parameters as well as DIFF – ON TIME _ OFF TIME Settings. This display is a very useful Feature of the system.




Remove the six screws from the front panel and put in a safe place. Then lift off the front panel and put this also in a safe place. The supplied temperature probes have about 2 meters of cable. You will almost certainly have to extend the cable on the panel probe. The cable is 3 core mains cable that is widely available. Make a good neat and waterproof job of joining this cable. You will have to decide where to put the controller box, close to the cylinder on a nearby wall or other surface will be ideal. When the box is fixed try on the front panel to make sure you can get to the controls and see the panel OK. Also make sure that the control box will not get damp or wet from water leaks in the system .You will also need a space nearby to put the battery. There are 5 wires that need to come in to the control box. These wires will come in through holes ( about 6mm ) that are drilled through the top, bottom, sides, or back of the box. Drill these five holes in a line about 25mm apart before you fix the box to the wall. Next securely fix the box to the wall using screws or plugs and screws depending of the surface construction. You will next need to run all of the wires in to the control box. Panel temp, tank temp, P/V panel, pump and battery. DO NOT CONNECT TO THE BATTERY YET. You will need to have about 15cm of each wire coming in to the box so that you can easily connect to the various connection points. Make sure that the other end of the battery wire is not connected to the battery. Strip about 5mm from the end of each wire and twist the strands together. It makes a neat job if at this point you take the time to Tin these wire ends. Connect the 12 wires to their respective connection points. DO NOT OVER TIGHTEN THE SCREWS.
Neatly dress the wires in to the back of the box and replace the control box cover  fixing securely with the six screws. Making sure that all three controls are fully anti clockwise now you can connect the battery. If all is well at this point the display will start to display in a cyclic fashion.