Question on fuses for solar

[Blaker55]

I have now mounted a 240 watt, 8 amp, 30 volt Schott solar panel and it will lead into a 25 amp mppt controller then into 2 new 12 volt deep cycle Wally batteries (120 amp hour each, and from there to a 600 watt pure sine inverter.<br /><br />I read that there should be a fuse near the positive terminal of the battery between it and the mppt controller.<br /><br />Also between the positive terminal and the inverter.<br /><br />How do I determine what size fuzes?<br /><br />Is there a difference between AC and DC fuses?<br /><br />Where do I obtain the fuse holders?<br /><br />Is there a fuse holder with heavy enough guage wire for between batteries and inverter?<br /><br />I am using 4 guage wire from batteries to inverter.<br /><br />Solar panel distributer says 10 guage awg will be plenty from panel to mppt controller and mppt to batteries. &nbsp;Is this correct?<br /><br />Thanks in advance for your replies.

 

[sparky1]

once all connected.WHAT are the voltage readings ?? What Voltage are you using from MPPT to battery's? 12,or 24 V.DC. from your battery's (IF) set up to 12 V.DC your inverter you say is 600 watts.&nbsp;4 guage is large enough to carry 600 watts @ 12.6 volts Full charge battery's..and YES they should be fused for your Protection incase a short developes.at least a 50 amp fuse.

 

[wrcsixeight]

One should Note that fusing is to protect the wiring, not the devices attached to them in most cases.<br /><br />I am using a 30 amp circuit breaker between my charge controller and batteries. &nbsp;I am also running 8 awg wires from my 130 watt panel to the charge controller and 10 awg wires from my 68 panel to the charge controller.<br /><br />

<br />From charge controller to battery I am using 4 awg cables.<br /><a href="http://www.ebay.com/itm/12V-DC-CAR-...otors_Car_Truck_Parts_Accessories&amp;vxp=mtr">http://www.ebay.com/itm/12V-DC-CAR-...otors_Car_Truck_Parts_Accessories&amp;vxp=mtr</a>&nbsp;<br /><br />I like this CB because at night I can push the button to break the circuit and reset my battery monitor.<br /><br />You can use ATC blade fuses, or Maxi fuses, or circuit breakers. &nbsp;While a larger fuse has less resistance, there is no real point in fusing larger than the capability of the charge controller. &nbsp;The charge controller should state the largest size fuse. &nbsp;Mine is a 25 amp controller, says 30 amp fuse size max.<br /><br />MPPT charge controllers are more sensitive to voltage drop than pwm controllers, and to get max performance the wiring runs should be as short as possible, and using thicker wire/ cable to minimize voltage drop. &nbsp;Also the charge controller should be placed as close to the batteries as possible without being in the same compartment.<br /><br />Most Wally world batteries use the 1 or the 5 hour rate to measure amp hours, where as most every other battery uses the 20 hour rate. &nbsp;Their group 29 "trolling batteries' are the only ones which might indeed be 'deep cycles'. &nbsp;If they say marine/rv/ deepcycle on them, they are not real deep cycle batteries, but dual purpose batteries, which are more tolerant of cycling than starting batteries but not by any large degree.<br /><br /> &nbsp;I won't bother with wally world batteries anymore. &nbsp;The Manufacturers have to cut every corner they can to meet wally worlds price demand. &nbsp;The battery johnson controls makes for interstate is not the same battery they make for wally world.<br /><br />My MPPT charge controller cannot accept 24 volt nominal panels. &nbsp;Double check to make sure yours can before attaching.<br /><br /><br />

 

[Blaker55]

Thanks for the replies.<br />My batteries are wired to output 12 volts to the inverter.<br />The mppt controller will supply 12 volts to the batteries. &nbsp;If I remember &nbsp;correctly, there is a switch inside that you can flip for 12 or 24 volts. &nbsp;I havent got that far yet so will need to go over the set up sheet in detail when I get to that point.<br /><br />I'm getting closer with lots of help from the members here.<br />The old saying that the devil is in the details also applies here so I want to get it right.<br /><br />Thanks again and looking forward to more wisdom.