pre-wired solar connection-- not as simple as I'd hoped

[doghouse_riley]

So I'm getting set to add a 200w solar panel to my Fleet Shell. Got the charge controller and the panel's supposed to arrive today. I watched the video from FWC where they walk through the solar pre-wiring and connections and was expecting to find a pair of leads going to the panel plugs on the roof and back, a pair of leads going to the battery and a pair of "load" leads. All ready to wire to the controller. Easy peasy!

When I uncoiled the wires in the battery compartment I see the leads for the panels (2 pairs of blk/red wires merged to 1 pair via wago connectors) terminating in butt connectors with the label "battery solar controller" which seems confusing but clearly this pair connects to the "PV" connector on the charge controller. There's a pair of green wires with female spade connectors labeled "Floodlights" which is obvious enough (an option I didn't get), another unlabeled pair of blue wires with female spade connectors that eventually disappear into the wall of the camper and presumably connect some other option I didn't get. And that's it.

Presumably I can wire directly to the battery from the charge controller since it will be mounted in the compartment. Would I use the same 10AWG wire coming from the panels? Also, I assume I should have a fuse between the pos battery terminal and charge controller, but what size?

but what do I connect to the "load" inputs on the controller?

I debated whether I should post this in the solar forum but the FWC pre-wiring seemed appropriate for this forum.

 

[JWL]

I assume you have a “new” camper? If so those videos are old and need to be labeled as such. I finally had to call FWC service department to clarify. I will have to go back and check my notes but there is no Load, the PV wires go to your controller and toward the back (on a Hawk Shell) was a separate set of wires that go to the battery. I didn’t use the load inputs on my Mppt I rely on my BVM for that, and I’m not sure if they even have a Load wire anymore. You might check with the service department for you model.

 

[Vic Harder]

Some solar controllers do not have LOAD outputs. My Victron 100/30 does not. As shipped to you, your camper battery directly powers the camper (via the kill switch) without going through any kind of load measuring device. If your controller has load outputs, you COULD use them... but get the wiring done without that complexity for now.

I've seen a newer video from FWC where they talked about not running separate load wires, and if they do install their MPPT, they snip the wires under the cabinet where the controller goes. Simplifies wiring for them.

So, to try and explain that, the wires you mentioned - pairs of blk/red wires merged to 1 pair via wago connectors) terminating in butt connectors with the label "battery solar controller"
- I assume these would be coming from the roof and from the rear portable solar plug, wired in parallel, and yes they would go to the PV inputs on the controller.

You will add a set of wires (as big as will fit into the controller) that will go to the battery to charge it from your solar panels/controller.

To use the LOAD connectors, there should be other wires connecting to the battery. A set that goes to the plug that goes to your truck, and a set that goes to the kill switch/DC fuse panel. The +ve wire that now goes to your fuse panel/kill switch would get pulled off and plugged into the LOAD connector +ve on your controller. The -ve load connector goes to ground/battery -ve post.

Question: Do you have a BMV as well? Then the negative wiring needs a bit more detail.

 

[doghouse_riley]

Yes, it's a new Fleet shell. The video actually came from the thumb drive they gave me with the keys, which has about 30 videos on different aspects of camper and a pdf manual.

I guess I assumed the controller also functioned as a monitor via bluetooth to your phone using their app. and somehow the load connections help serve that function. But it sounds like I may still need a BMV to monitor the battery state (there is a simple volt meter next to the 12 accessory plugs). I honestly don't find the manual with the victron very helpful in terms of wiring, but being a noob doesn't help.

So for now connect the controller directly to the battery (fuse needed?) and to the panel wires. Is there any reason to wire to the load connectors? Should I just add a BMV?

thanks for the help!

 

[Vic Harder]

How far is it from the controller to the battery? I don't put a fuse in there because the distance is so short and there is no metal around to worry about, BUT others have indicated that a fuse is a good idea to protect the MPPT/controller from the battery. Which controller do you have? If it is rated at 15A, a 30A fuse would be plenty.

Yes, you can get some info about what the controller is doing, but not what SOC the battery is in. So yes, a shunt based monitor is a very good idea.

Is there a reason to use the Load connectors? Yes... they can help protect the battery by disconnecting it in the event that the battery is being drained too far. I'd consider them optional.

 

[rando]

Great advice from Vic, as usual. I would agree that a fuse is not necessary if you are mounting the solar controller in the battery box, or close to the batteries. The controller has a built in fuse to protect itself, so an additional fuse would only to be to protect the wiring. If the wiring is long and had the potential to be chafed or damaged, then a fuse would be wise.

Skip the load terminal for now, you can wire them up later if you choose. I agree on the advantages of using it (and use I use it on my setup) but one thing to note is that it is current limited and will shutdown if you try to draw more than 15/20A depending on the model. This has two implications, you can't use an inverter through the load terminals, and under certain circumstances, such as the fridge starting while the furnace is on and the lights are on, you can momentarily exceed 20A, causing everything to shutdown.

 

[Dessmo]

I would be careful putting a fuse between the battery and MPTT charger. If the controller lose power but are connected to the solar panel you burn the control unit and have to replace it. Under normal circumstances there should not be a need for a fuse here.
One thing to consider regarding the load output. I have set my Victron up so I run the cooler from the load output. Then I can turn off the main switch killing everything else than the cooler. The load output can be turned on/of via the BT app if required, it can also be set up to turn off at a certain voltage. I am running a lithium battery where I can monitor the load and how much I have left. If you are running a led battery, a shunt and a battery monitor/BT app will do the same.

 

[rando]

I am not sure this is actually a concern. I have disconnected the battery on my MPPT many times while under power, with no issues. Victron also seems to be OK with this configuration - there is a fuse built into to the controller itself, and in many of their suggested configurations there is a disconnect between the battery and charge controller. Not come down too hard on this - but this idea has lead to folks building all sorts of crazy systems to disconnect the solar panels through their BMS, which is really unnecessary.

Good idea about the load connections. That is why I use mine as well - it is nice to have a bluetooth master shut off, and it gives you the currents that your loads are drawing. This is a little different than what the BMV gives you, as it only provides the net current into the battery (charge - loads).

I would be careful putting a fuse between the battery and MPTT charger. If the controller lose power but are connected to the solar panel you burn the control unit and have to replace it. Under normal circumstances there should not be a need for a fuse here.
One thing to consider regarding the load output. I have set my Victron up so I run the cooler from the load output. Then I can turn off the main switch killing everything else than the cooler. The load output can be turned on/of via the BT app if required, it can also be set up to turn off at a certain voltage. I am running a lithium battery where I can monitor the load and how much I have left. If you are running a led battery, a shunt and a battery monitor/BT app will do the same.

 

[JWL]

I did not run a fuse to mine and I did not hook up the load. But my electrical needs are pretty simple. Maybe when I go Lithium and a Fridge/freezer I will hook it up, but between the Victron Bluetooth app and the battery monitor I have all the info my little brain needs. If you are looking for a battery monitor I went with a AiLi from Amazon, it was under $40 and I have been very happy with it. (Saving for the fridge.
Did you get your battery hooked up?

 

[doghouse_riley]

thanks for all the input! I did manage to get it wired up (minus the load lines). I'm still waiting on some hardware to mount the panel on the roof but I was able to plug it into the socket on the rear of the camper and prop it up to face the sun. Everything seemed to be in order, current flowing into the charger and battery getting charged (based on the indicator lights and the app readings). I still need to wire in a monitor.

I didn't add a fuse between the MPPT and battery figuring its built-in fuse covers that and it's only about of foot of wire. I did add an in-line 15 amp fuse on the positive line between the panel and MPPT.

Rando, for the connection to the fridge are you wiring the (+) and (-) lines directly between the fridge and MPPT's load connections?

 

[Dessmo]

Ok, I have not seen any fuse on my Victron control unit, is it an automatic that you find in the app settings? I would say it makes sense, I know people who have burned their controller disconnecting the battery by a mistake. Should be easy to avoid that by putting a safety system into the control unit.

I am not sure this is actually a concern. I have disconnected the battery on my MPPT many times while under power, with no issues. Victron also seems to be OK with this configuration - there is a fuse built into to the controller itself, and in many of their suggested configurations there is a disconnect between the battery and charge controller. Not come down too hard on this - but this idea has lead to folks building all sorts of crazy systems to disconnect the solar panels through their BMS, which is really unnecessary.

Good idea about the load connections. That is why I use mine as well - it is nice to have a bluetooth master shut off, and it gives you the currents that your loads are drawing. This is a little different than what the BMV gives you, as it only provides the net current into the battery (charge - loads).

 

[PaulT]

Many of the charge controllers say to hook up the battery before hooking the solar panels. To that end I added a circuit breaker with a push to disconnect and a lever to reconnect the panels to the charge controller. That way, I can disconnect the panels prior to working on the electrical systems.
Eaton Bussmann 285 Series Resettable Circuit Breakers Surface Mount up to 150A

I used a 50 amp breaker on mine because I already had one.

Paul

 

[rando]

Ok, I have not seen any fuse on my Victron control unit, is it an automatic that you find in the app settings? I would say it makes sense, I know people who have burned their controller disconnecting the battery by a mistake. Should be easy to avoid that by putting a safety system into the control unit.

On the 10,15 and 20A models there is a user replaceable automotive style blade fuse built into the controller, next to the VE.direct port.

If the controllers actually burnt out from disconnecting the battery, anyone with a lithium battery with a BMS would have a ticking time bomb, the BMS can disconnect the battery from the controller without warning. I wonder what sort of controller your friend was using, but with Victron at least, this is not an issue.

 

[rando]

There are a couple of reasons they suggest connecting the battery first, primarily because MPPT charge controllers can support multiple battery voltages. Without the battery connected, the controller can't sense the voltage and doesn't know what to output. I think once it has been initialized, it will remember the battery voltage, and hopefully it would default to 12V if it can't figure it out. Probably safer to provide 12V to a 24V system, then 24V to a 12V system.

Regardless of any of this, a disconnect on the panel side is a great idea!

Many of the charge controllers say to hook up the battery before hooking the solar panels. To that end I added a circuit breaker with a push to disconnect and a lever to reconnect the panels to the charge controller. That way, I can disconnect the panels prior to working on the electrical systems.
Eaton Bussmann 285 Series Resettable Circuit Breakers Surface Mount up to 150A
I used a 50 amp breaker on mine because I already had one.

Paul