Help with Cable Sizing and Fuses


  • Good afternoon,

    I am pretty new to the world of solar pv etc...and I am currently in the process of designing a system for our community allotment to provide power which will allow us to pump water from water collection tanks to other tanks on the allotment.

    I am hoping that if I breakdown what I know, someone can help me with what I don't know.

     

    2x Solar Panels, mounted in series.

    Each Panel: 260W, Vmpp 30.7V, Impp 8.50A, VoC 37.8V Isc 9.01A, Maximum System Voltage 600V, Maximum Series Fuse 15A

    These will feed into my 60A EcoWorthy MPPT Charge Controler:
    60A 12/24/36/48V MPPT OLED Display Solar Charge Controller Regulator | ECO-WORTHY – eco-worthy-uk

    This will charge a battery bank made up of 1x 170Ah and 1x 90Ah Powersafe SBS Batteries (couldn't get the same Ah unfortunately) which I intend to parralel up.

    The water pump is a 12V, 260W pump.

     

    The complication is that the solar panels will be sighted near our polytunnel and the pump will be sighted some 50metres away. I was looking at cables etc..until someone suggested that I could have an isolator on the feed coming from the solar panels, followed by an anderson connector to disconnect the panels from the charge controller easily and safely. If I was then to mount the batteries and charge controler on a little trolley, it could juct be rolled down to the pump where a different sized Anderson Connector would allow me to plug the pump into the load of the charge controler to power the pump.

     

    I would be really grateful for input as I am struggling with the following:

    1. Cable sizes I need to go from the MC4 connectors off my panels to the charge controller. (distance will be no more than 12ft) (I did this caculation Isc x 1.25 x 1.25 = 14Amp which means a 14AWG cable)

    2. Cable gauge to use to parallel up my batteries (they come with M6 terminals) - not sure how to calculate

    3. Cable gauge to run from the charge controller to the pump (I did this calcuation 260w/12v = 22A meaning the 14AWG cable would also work for this part)

    4. Where I should consider fuses, and which kind and what size

    Any other considerations also greatly appreciated. As Eco-worthy only sell some of the bits I need any suggestions (UK) of where I can pick them up would be appreciated.

    Many thanks

    Duncan 



  • You can use a 12 AWG cable for the 12ft run from the solar panels to the charge controller to handle the current safely. For paralleling the batteries and running from the charge controller to the pump, use a 10 AWG cable to accommodate the higher current and minimize voltage Slope Game drop. Place a 15A fuse between the panels and charge controller, and a 25A fuse between the charge controller and the pump for protection.


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