●Wiring the Mppt Controller Box
When you have solar pump, controller, solar panels, power cables and other accessories ready to be connected, follow steps as below.
1.Wire the pump, panels and optional battery to the control box according to the wiring diagram below. When wiring the pump do not worry about the wiring orientation, only connect the pump wires to the controller and make sure the pump wire does not touch each other. Then, test the system------ if the wiring is incorrect , the pump will run backwards and the two wires has to be swapped over to get the pump run correctly.
2.If use a battery then the wiring is per the bottom diagram. Make sure the polarity is connected correctly: plus to plus, minus to minus. Charge controllers generally have the following connections. Battery, Panel and Load either written or in pictorial form.
3.The pump controller solar PV input is connected to the load terminals of the charge controller. As a safety margin we recommend the charge controller be able to supply at least 1.5 times the pump requirements.
Basic formula: Load (amps) = pump wattage / voltage = amps.
Amps x1.5 = charge control load.
eg. A 300 watt 24 volt pump. 300/24 = 15 amps.
15A x 1.5 =22.5amps.
The charge controller must be able to supply 22.5 amps to the load at 24 volts.
Be very careful not to reverse or shorten the terminals when wiring a battery. While the voltage is low the current capability is in the order of hundreds, if not thousands of amps and can do serious damage. We advise you remove all metal wrist bands or watches before you start. A short across a metal watch strap will make it glowing red hot in seconds, causing very serious burns. Solar PV panels can also produce a lot of energy when connected together, which means caution must also be exercised here as well. A dark cloth to shade the panels is a good precaution to reduce the power output.
4.It is important that the water sensors are connected properly. The water low (WH) and water common (WC) are very important because they protect the pump from running dry. Do not link out WH under any circumstances. (the only exception is for troubleshooting) The sensor terminals TC and TH can be left disconnected if you are not using a header tank or don’t care if the water flows out on the ground once the tank is full. The sensor probes are all the same, just different colored wiring. For clarity we recommend you use the probes with white wires as the common probes (WC and TC) and the other colors for WH and TH