James Masciuch avatar image
James Masciuch asked

New to the Solar Setup in our Trailer - Want to add Phoenix Inverter

We just bought a 2022 Intech Sol Horizon Rover Camper Trailer. We had our dealer install a solar package that Included 300 watts of panels to a SmartSolar 100/30 MPPT feeding dual 120Ah Lithium batteries (240ah Total) with Monitoring via the BMV-712. (See the picture below)


We haven't had it but a few days but I would like to add a Phoenix Inverter 12/1200 and connect it to our existing breakers by way of our Progressive Dynamics PD4135. I realize I need a transfer switch, either manual or automatic, and will need to turn off the converter manually in the PD4135 every time I want to run off the inverter.

  • Do I connect the inverter to the shunt of the BMV-712?
  • Should I look at the Filax 2 transfer switch? Why is it so pricey compared to other options? Is it worth staying in the Victron Brand?
  • Do I need to upgrade the gauge of my cables? They look puny compare to other installs I've scene.
  • Can someone help me gain a better understanding of what parts I will need to accomplish this? What size breakers, wire, etc?
MPPT ControllersBMV Battery MonitorPhoenix Invertercampervan
img-1566.png (11.2 MiB)
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3 Answers
basil katakuzinos avatar image
basil katakuzinos answered ·

Hi there, the phoenix is great BUT you might be better suited by a multiplus or multiplus compact as this will accept your existing AC source (A generator or shore power) and combine them with your solar it has a transfer switch inside it. Basically an inverter+charger+transfer switch.

Regardless of what choice you make i will try to answer your questions below.

  1. All loads, including the inverter need to be placed infront of the shunt (Only the battery should be behind the shunt), this way the BMV can see everything going in and out of the battery.
  2. The Filax 2 is an automatic transfer switch, this means it switches power so quickly that all of your computers stay on and do not notice the change in power, it is not necesary and if you feel like you want this feature you may be better suited with the above mentioned multiplus as it has a transfer switch integrated within it.
  3. The guage wires required will be on the spec sheet of the inverter you go with, you WILL need thicker cable probably as a 1200va inverter can easily peak at over 100 amps and can draw over 80 amps continuous!
  4. I avoid DC breakers, fuses tend to do the job for me and are the standard where i live. Before we talk about what you need i would like to hear if you think the multiplus or phoenix is the better option for you
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James Masciuch avatar image
James Masciuch answered ·


Thanks for the fast response. I guess the reason why I was shying away from the Multiplus charger/inverter was because 1. cost 2. It seemed redundant. The PD4135 is currently acting as the converter to charge the lithium batteries and I saw no need in replacing it. 3. comfortability with the inverter as tech. I've been using inverters in my cars for 20 years now and it is technology that I know. There is a lot out there solar tech wise and keeping everything straight is tough.

This is my first jump into the DIY solar tech. I've been using Goal Zero products for 10 years but as you know they're just plug and play and quite frankly idiot proof. As of a month ago I didn't know Victron as a company. My RV dealer introduced it to me when he told me about what solar packages he could install.

We are not full-timing in the RV, although in the summers we tend to be on the road for trips up to 5 weeks. Ultimately I want something that can run our TV and AppleTV, and charge a laptop, drone and cameras. The necessary locations are on opposite sides of the trailer. At first I thought of locally installing two small 12/375 or 12/500 inverters but bringing thick cable to the opposite ends cleanly would be a pain in the butt. So I thought a single 1200VA inverter tapped into the mains could be an easy solution. I just bought a 12/1200VA for $300 but could return it if there is a better solution. I was considering a manual transfer switch as it would be an easy step to click it over to the inverter for power and flip the breaker for the converter. Then I went down the road of automatic transfer switches, and read great reviews of some for $100.

I have information overload at this point and just want an easy solution to power just a couple devices onboard without cutting up our beautiful, expensive new camper.

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alex-rhys-hurn avatar image
alex-rhys-hurn answered ·


I have a trailer and have done what you are thinking. I hear you on the multiplus, and it didnt work for me either. So, go for it. I have only a small phoenix, but the principle is the same.

The killer app for me, is the ability to connect then load output of the MPPT to the inverter control port so that the mppt can turn off the inverter when the battery gets low. Here are some photos of mine.



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