17 replies to this topic

[Karlton]

Hey gang - I wanted to share the progress of a solar install and request feedback on some ideas.  Thanks in advance.  

 

There was a positive and negative wire in the battery compartment of my 2017 hawk labeled 'solar battery'.  After searching around in the cabinets near the water heater and by the fuses with no luck, I discovered the coiled solar wires behind a panel directly below the sink and was thrilled they were so easy to access.  The intent of FWC must have been to mount the controller in this area. 

 

The 'rear solar' and 'roof solar' wires were connected via a push-in connector (I'm not sure of the connector name) with a single positive and negative wire exposed.  There were also two wires not connected to anything, which I assume are the end of the 'solar battery' wires in the battery compartment.  

 

I do not want to have my solar controller directly below the sink, so I'm going to run the wires down to the battery box where I'm going to mount a Victron MPPT solar controller.  Here are my questions.

 

1.  The positive solar wire that will connect to the solar controller has a fuse.  Do I need to keep this inline fuse?

2.  The positive battery wire that will connect to the solar controller has a fuse.  Do I need to keep this fuse?

To note, the MPPT has a fuse.  I am aware of the reversed polarity of the wiring due to the Zamp connection, so I am going to make sure of the polarity and if I need a fuse in the wire, I'll install on the positive wire.  

 

I mounted the Renogy 100w panel to a piece of angle aluminum, and will mount the aluminum to the Yakima tracks.  I used mounting brackets for a little extra space.  I like the set up and ease of removal, and owe a few folks on the forum a thanks for the description and photos of their set-up.

 

 

[ckent323]

The Victron Controllers have a fuse.  That should protect the Controller from a battery short.  Further, I do not think you need a fuse between the solar panels and the Solar controller.

 

However, here is what Windy Nation recommends:

 

Solar Panel fusing

Commercially made solar panels over 50 watts have 10 gauge wires capable of handling up to 30 amps of current flow. If you connect these panels in series, there will be no increase in current flow so fusing is not required for this string.

This is not the case when you have panels connected in parallel, as when connected in parallel the system current is additive. For instance if you have 4 panels each capable of up to 15 amps, then a short in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed 30 amps causing that wire-pair to potentially catch fire. In the case of panels in parallel, a 30-amp fuse is required for each panel. If your panels are smaller than 50 watts, and use only 12 gauge wires, and 20 amp fuses are required."

 

I think most 100 W panels have a short circuit current of around 6 A and 150 watt panels are around 9 A So even if you have two in parallel you will be well under 30 A. Therefore I do not think you need to add a fuse. 

 

Now I do think you need a fuse between the battery and your distribution panel.  Not sure what is appropriate and it depends on the loads you will be running but my guess is you will not ever be pulling over 20 A unless you connect to your vehicle charging system.

 

I will defer to Vic, Rando, ntsqd and others who may have better advice here.

 

Craig

Edited by ckent323, 28 March 2018 - 05:52 AM.

[rando]

Craig is absolutely right - no need for a fuse/breaker between the controller and panels.   It sounds like you are going to mount your solar controller in your battery box (which is the best option), in which case you don't need a fuse between it and the battery.    The reason for this is that the fuse is primarily to protect the wires coming off the battery (an unlimited current source).   Since the solar controller is right next to the battery anyway,  the wire between the battery and the solar controller would be the same length as the wire between the battery and fuse, so you are not adding any protection with a fuse.   You do want to fuse any wires attached to the battery that leave the battery box. 

[JaSAn]

 . . . Here are my questions.

1.  The positive solar wire that will connect to the solar controller has a fuse.  Do I need to keep this inline fuse?

2.  The positive battery wire that will connect to the solar controller has a fuse.  Do I need to keep this fuse?

 . . .

 

My 2¢:

1. I would go with the recommendation for your charge controller, Morningstar recommends one.  Even if no recommendation it will not hurt to have one in line; it makes for an easy disconnect of the panels from the charge controller if you need to for any reason.
2. All positive wiring coming from the battery needs a wire size appropriate fuse (you really don't want your battery to short).  ABYC specifies a fuse within 8 inches of the battery.  There are fuses that attach directly to the + battery terminal.  Again, it doesn't hurt to have one.       

You want to fuse any + wire that can short and cause a fire.

      http://bdfuses.com/fusesnwires.php

 

 

jim

[ckent323]

Jim,

 

Does the Morningstar controller have a built in fuse like the Victron controller has?  If so I do not understand the need to double fuse.

 

As for the fuses already in place in Karlton's wiring, I suppose there is no harm in leaving them in place as long as they are appropriately sized for the circuit and loads  As I recall all the solar wiring in the FWC is 10 ga. so it can handle up to about 20 amps over about a 15 or 20 foot run without causing too big a voltage drop so a 15 A or 20 A fuse is an appropriate size  

 

BTW: The Victron Solar Controller has a 20 amp fuse.

[Vic Harder]

I'm with rando on this one.  And Craig when he indicates you need a fuse between your batteries and thd DC distribution panel.

[Karlton]

Excellent - thanks very much.  Looking forward to having this install completed.

 

Best

[Karlton]

I've wired my 100 W Renogy solar panel according to the diagram below.  The Victron app shows it is on bulk state with a current value of 4.0 A, but the battery monitor is showing a current of 0.00 A. Should the battery monitor show a positive current when the panels are charging the battery?  Or does the monitor only show the draw (negative current) on the batteries.  I turned on some appliances, and the current showed -0.35 A.

 

Every time I think I have something figured out, a new question emerges.

 

Thanks!

Edited by Karlton, 05 April 2018 - 05:41 PM.

[ckent323]

I believe you want the negative side of the Solar controller connected to the "in" side of the shunt (as shown) and the "out" side to connect to the battery bank.  The load connects to the battery bank directly (or to the load terminals on the Solar controller).

 

I made a mistake on this connection and I think Vic did too.  As I recall Rando set us both straight.  ;-)

[Karlton]

I went back and read some posts on the wiring of solar and a BVM and found the error!  The current on the BVM matches that on the MPPT app, and when I draw a large load it shows a negative current on the BVM but not the MPPT.  

 

Best,

Karl

Edited by Karlton, 01 April 2018 - 11:46 PM.