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Philip Jones · 03-19-2019, 10:57 AM

Hi all,

Context: 2017 FC FB twin

I have done a lot of reading on the forums about solar and lithium batteries. I am contemplating a switch to Li batteries (Battle Born) and I thought I should also consider adding 400W of solar at the same time. I currently have no solar power.

I already have a Victron 712 battery monitor installed in the 'rat's nest'. The attached photo doesn't show it because it was pre-Victron installation and I forgot to take one post-installation. (I spliced the negative leads coming into my trailer in the rat's nest and attached the battery ends to the pre-shunt terminal and all of my other negative leads post-shunt.)

Here are my questions; I would be very grateful for any answers:

1) I have read that the pre-wiring is 10 ga yellow and green wires. Are those the wires that I can see in the top left of the attached photo?

2) On the roof, there are three 'ports' that I presume is attached to the pre-wiring. I assume this is a combiner box. How do the solar panels connect to those ports? Is there some sort of standard connector, or is it necessary to purchase adapters?

3) If I have four 100 W panels, would I connect two of them in series (occupying one of the three combiner ports) and then connect the other two in parallel (ie. directly to the other two combiner ports)?

4) I plan on purchasing a Victron 100/30 MPPT charge controller. I am confused about where the electrical output from the solar panel pre-wiring turns into the input to this controller. Are the yellow and green wires just floating freely in the rat's nest, and then I connect the controller's panel connection to these wires?

5) For the connection from the charger controller to my batteries and integrating this with the shunt (to ensure the electrons are counted), what wires connect where? Negative lead of controller to the post-shunt terminal and positive to a bus bar?

Very sorry for my ignorance on this matter. Thank you for any assistance offered.

Phil

AirMiles · 03-19-2019, 07:01 PM

Here are my questions; I would be very grateful for any answers:

1) I have read that the pre-wiring is 10 ga yellow and green wires. Are those the wires that I can see in the top left of the attached photo? Yes

2) On the roof, there are three 'ports' that I presume is attached to the pre-wiring. I assume this is a combiner box. How do the solar panels connect to those ports? Is there some sort of standard connector, or is it necessary to purchase adapters? You use SAE connectors with 10 Gauge wires: https://www.amazon.com/SPARKING-10AW...s%2C182&sr=8-1 You can cut one of these in half to make two connections. The rubber coated square is the positive side.

3) If I have four 100 W panels, would I connect two of them in series (occupying one of the three combiner ports) and then connect the other two in parallel (ie. directly to the other two combiner ports)? No, you connect two sets of two pairs and only use two ports on the Zamp rooftop box.

4) I plan on purchasing a Victron 100/30 MPPT charge controller. I am confused about where the electrical output from the solar panel pre-wiring turns into the input to this controller. Are the yellow and green wires just floating freely in the rat's nest, and then I connect the controller's panel connection to these wires? Yes, but you wire a switch on the positive wire. See photo for how to connect: http://www.airforums.com/forums/atta...0&d=1539352234

5) For the connection from the charger controller to my batteries and integrating this with the shunt (to ensure the electrons are counted), what wires connect where? Negative lead of controller to the post-shunt terminal and positive to a bus bar?
I do not have a BMV-712, but think the shunt is between the bus bar and the battery and all negative loads are connected to the shunt. The negative bus bar is connected to the shunt. The negative from the Victron controller gets connected to the bus bar. The positive from the Victron includes a 40A breaker and then connects to the positive bus bar. See all these connections in the photos from question 4 with the orange/black (positive) and black (negative) 6 gauge wire. Here is how you connect the 6 gauge output wires from the Victron controller to the bus bars: https://www.lowes.com/pd/Blackburn-2...r-Lugs/4582297

I did the same installation as you are contemplating and documented my installation and performance results in the Solar Show & Tell thread: http://www.airforums.com/forums/f448...ll-181608.html This installation is capable of maxing out the 30A charge capability of the Victron 100/30 under perfect sun conditions. The Victron 100/30 is the correct size controller for four 100W panels.