Wire Shore Power into Solar Configuration

[Riverbug]

I have a fairly specific question for our future solar installation... Assume we will have a Victron Multiplus, but I guess it doesn't matter what transfer switch is used. I want the ability for the system to identify whether we are plugged in to shore power or not and automatically switch between shore power and solar/inverter power. My question is, where does the switch physically get connected to the shore power wiring? I assume it could be done behind the power panel vs directly at the plug at the back of the trailer? I can't see a reason it would have to be connected at the plug, but I see most wiring diagrams show it that way, but guessing that's just the way to show the shore power is connected to both the power panel and the Multiplus (in my case)?

[sirtate]

I have a fairly specific question for our future solar installation... Assume we will have a Victron Multiplus, but I guess it doesn't matter what transfer switch is used. I want the ability for the system to identify whether we are plugged in to shore power or not and automatically switch between shore power and solar/inverter power. My question is, where does the switch physically get connected to the shore power wiring? I assume it could be done behind the power panel vs directly at the plug at the back of the trailer? I can't see a reason it would have to be connected at the plug, but I see most wiring diagrams show it that way, but guessing that's just the way to show the shore power is connected to both the power panel and the Multiplus (in my case)?

The MultiPlus has an internal switch.
So, 110v power goes from the trailer power socket to the MultiPlus, and then from the MultiPlus to the fuse panel. (,Assuming the old fashioned converter has been disabled).

The MultiPlus will power the coach from the inverter if need be, and charge the batteries when shore power is available.
The switch from one to another is seamless.

Sent from my LM-G900 using Tapatalk

[Paul & Deb]

I have a fairly specific question for our future solar installation... Assume we will have a Victron Multiplus, but I guess it doesn't matter what transfer switch is used. I want the ability for the system to identify whether we are plugged in to shore power or not and automatically switch between shore power and solar/inverter power. My question is, where does the switch physically get connected to the shore power wiring? I assume it could be done behind the power panel vs directly at the plug at the back of the trailer? I can't see a reason it would have to be connected at the plug, but I see most wiring diagrams show it that way, but guessing that's just the way to show the shore power is connected to both the power panel and the Multiplus (in my case)?

Chad, I'm wondering why you want to add this additional step? One of the beauty's of the Multiplus is the fact that you never have to worry about this aspect. I pulled 10-3 romex from the front compartment into the trailer at the power center, then I disconnected the wire the factory connected from the power panel and connected the two ends using splicing blocks so now the 10-3 runs from the rear power port to the Multiplus. Then a second run of 10-3 connects to the power center and runs to the front compartment connecting to the Multiplus. Disconnected the WFCO converter completely and we're good to go. No need for a transfer switch. If you're plugged in to shore power the Multiplus internally switches to that source and when you're not, it inverts from your 12v battery bank to provide the 110vac to the panel.

Maybe I'm missing something and you have a very specific reason you want to do all this manually.

[Riverbug]

Thanks Paul and sirtate for the responses. I wasn't entirely clear on what I was asking but I did figure it out from the responses. Not sure if you would know the answer to this follow up question... I have the WFCO 8735 power panel which has the integrated converter/charger. I cannot separate the two which is the reason I (and others) cannot replace the charger with the typical PD lithium charger that most people upgrade to when they get a lithium battery.

I'm wondering how I will be able to connect the Multiplus to the power center if I cannot separate the converter from the charger? Wonder if I have to get a new power center? I have to dig into that a bit more...

[Paul & Deb]

Thanks Paul and sirtate for the responses. I wasn't entirely clear on what I was asking but I did figure it out from the responses. Not sure if you would know the answer to this follow up question... I have the WFCO 8735 power panel which has the integrated converter/charger. I cannot separate the two which is the reason I (and others) cannot replace the charger with the typical PD lithium charger that most people upgrade to when they get a lithium battery.

I'm wondering how I will be able to connect the Multiplus to the power center if I cannot separate the converter from the charger? Wonder if I have to get a new power center? I have to dig into that a bit more...

Chad, you will simply disconnect the 3 wires that are for the converter and you can just leave it installed and coil the wire up. I just finished doing this myself. You will also have to run 10-3 Romex from the power center to wherever you plan to install your Multiplus and rewire the 110v side of the power center. Super easy.

[SolarPoweredRV]

I have a fairly specific question for our future solar installation... Assume we will have a Victron Multiplus, but I guess it doesn't matter what transfer switch is used. I want the ability for the system to identify whether we are plugged in to shore power or not and automatically switch between shore power and solar/inverter power. My question is, where does the switch physically get connected to the shore power wiring? I assume it could be done behind the power panel vs directly at the plug at the back of the trailer? I can't see a reason it would have to be connected at the plug, but I see most wiring diagrams show it that way, but guessing that's just the way to show the shore power is connected to both the power panel and the Multiplus (in my case)?

It might be helpful if we take a look at how electricity flows inside your coach...

When you plug into Shore Power, your coach is energized with 120 volt electricity, this energizes all your appliances and your outlets inside the coach. Additionally, 120 volt power is supplied to your Converter, the Converter "converts" the 120v electricity into 12v electricity to charge your battery while simultaneously supplying energy to all of your 12v circuits. When you disconnect Shore Power, your battery supplies 12v power to the 12v circuits.

When you add an Inverter/Charger (like the Victron Multiplus) to the electrical system the electricity flows differently. The only reason to add an Inverter to your electrical system is to have 120 volt electricity in your coach without being plugged into Shore Power. This 120 volt electricity is "inverted" from your 12v battery(ies). The larger your battery bank, the longer you can enjoy 120v electricity inside your coach.

With an Inverter hard wired into your coach the electricity flows from the Shore Power connection into the Inverter/Charger and then into your coach's 120v electrical system. Additionally, because the Inverter is connected to your battery bank, the Inverter/Charger can take the place of the Converter and charge the batteries while simultaneously supplying enough 12v energy to power all the 12v circuits (this is why you need to disconnect the OEM Converter).

Getting back to your original question, the Inverter/Charger has an internal "Transfer Switch" that will automatically switch between Shore Power and Inverted Power. In the case of the Victron Multiplus, this switch over happens instantaneously whenever shore power is lost. Conversely, when Shore Power comes back, the Transfer Switch is delayed for a few seconds in order for the Inverter to synchronize the inverted electricity with the electricity supplied from the Shore. Once the two energy sources sync up, the Transfer Switch engages (you will hear a thud) and you will be running on Shore Power.

When adding Solar to your coach, you are simply adding a secondary method to recharge your battery bank. The electricity from the Solar panels flows into a Solar Charge Controller which is directly wired into your 12v battery bank. Oddly enough, that is how simple Solar really is.

[Ynot4me2]

BTW, thank you for asking all of these questions. Some of us, including myself, are just about to start this project. I'll be starting with a DYI Lifepo4 280ah battery and BMS which I plan to temporary locate in the same outside location on the A-frame. Phase 2 of my project is relocating it under the dinette bench along with multiplus 2000w or 3000w. Phase 3 is solar and maybe a 2nd Lifepo4.
I notice that you also have a 22mle. Theres a lot of space under the dinette bench beside the pump and you can also go in the space behind the converter under the pantry. I might also replace my portable EMS with a hardwire and also put there.

Sent from my SM-P610 using Tapatalk

[Riverbug]

Thanks again for the responses. I think the lightbulb in my head is at least starting to flicker. But I'm still not clear as to how I will have 12v power for lights and such once I disconnect the converter/charger on the power panel. So the batteries are only connected to the multiplus, and only 120v (inverted) is connected between the multiplus and power panel. So that means the only way to run 12v appliances is by running the inverter? But the converter was disconnected, so is there also a 12v out from the multiplus to the 12v side of the power panel?

[Riverbug]

BTW, thank you for asking all of these questions. Some of us, including myself, are just about to start this project. I'll be starting with a DYI Lifepo4 280ah battery and BMS which I plan to temporary locate in the same outside location on the A-frame. Phase 2 of my project is relocating it under the dinette bench along with multiplus 2000w or 3000w. Phase 3 is solar and maybe a 2nd Lifepo4.
I notice that you also have a 22mle. Theres a lot of space under the dinette bench beside the pump and you can also go in the space behind the converter under the pantry. I might also replace my portable EMS with a hardwire and also put there.

Sent from my SM-P610 using Tapatalk

Well, I'm glad this is helping. I've got the overall concept down but the details are starting to trip me up.

I have already installed a 206AH SOK lithium battery under the dinette by the water pump. My plan is to remove the panel between the dinette seat (below the seat) and the space behind the power panel. It's actually wide open behind the power panel too. I will then move the water pump to the side (I wish they wouldn't have put the pump and all the wiring right in the middle of that space). Between the dinette space and the space behind the power panel there's enough room for another SOK battery, the multiplus, and such.

[Riverbug]

Okay all. I think I figured it out. I got messed up a bit because I'm looking at all the various solar system diagrams online and some show the multiplus with a separate transfer switch, others show no connection to DC block. After thinking about it more based on your responses, I realize I need to ignore some of the videos and diagrams I've been studying. I see the source of 12v power will still be from the batteries directly to the DC panel, and no transfer switch is needed. Thanks again!