WF-T30 RV transfer switch questions...

[culty]

I'm a total noob when it comes to solar/off-grid, but nonetheless I'm diving head-first into a solar install on my RV. It's mostly installed (and temporarily working woohoo!), but I still have a few pieces to figure out. (I've listed the specs of my current starter solar configuration at the bottom of the post). The goal is to get the cabling all routed into the RV through the roof ASAP, hopefully this weekend.

My RV has a WFCO WF-T30 automatic transfer switch. I watched Will's video on wiring a similar model from WFCO up, but what I understood from his comments is that he was only dealing with shore power + PV, NOT generator (he mentions something along the lines of, "...maybe your generator isn't working or it's completely removed"). I have an Onan 4000 on board, and would love to have the option of charging batteries/running power from generator, shore power, or PV.

My question is two-fold:

1) I've heard a few warnings about cheap transfer switches not doing their job and as a result frying RV electrical systems when they allow power from two sources at the same time. Is this a real concern? And if so, is this brand/model transfer switch one I can rely on to handle sources safely and intelligently?

2) Can I wire in house power, PV, AND generator through this transfer switch?

If the answer is no to any of the above questions, is there a transfer switch or different approach that I should be looking at instead?

I have the panels on the roof and the batteries/all-in-one under the bed. I'm temporarily running PV wires off the roof and in under the bedroom slideout, and likewise running a 30a cord from the Growatt out of the same spot for shore power connection at the moment. Any and all help is GREATLY appreciated!

Here are the specs of my current (working) system:

8-24v20ah batteries wired in parallel
3-395w ~40v10a bifacial panels wired in series
1-Growatt SPF 3000TL LVM 24v all-in-one

 

[time2roll]

The WF-T30 will never connect both sources at the same time. Not an issue.

Are you getting power to the RV by plugging the main utility cord into the GW-3000-TL? This would not seem to be the best method.

I believe the most common would be to feed the WF-T30 with utility power and the generator. Then the WF-T30 output goes to the GW input. The GW output feeds to the 30 amp breaker/distribution panel.

Of course the oem converter needs to be disabled.

The transfer switch only controls the 120v power feed in. The Growatt controls the solar charging vs utility/generator charging.

 

[culty]

Ahh, got it. So if I'm understanding correctly, I would leave the generator/shore power running into the WF-T30 alone, and reroute the power out of the WF-T30 from the breaker panel to the Growatt. Then run AC out from the growatt to the AC IN on the 30 amp breaker/distro panel (where the WF-T30 was previously connected)? Do I have this right?

Then find the on-board/oem power converter, and disable/bypass it (since the Growatt will handle that now)? I hadn't thought of this part, so I'm not sure exactly what that looks like, but I can start googling it and poking around to understand what I'm dealing with on my specific rig.

And for my current GW AC out configuration, I'm currently off-grid, so when I got my panels up on the roof and the batteries/growatt on board 1-2 weeks ago, I just ran a 10-3 wire out under the bed to a 30a receptacle as a stop-gap so I could have shore power on immediately while I made sure I had the right idea on this internal wiring stuff. It was only intended as a temporary measure, and now that I have most of the pieces in place, the hope is to get it all rewired permanently this weekend. I kind of suspected I could keep the wiring all in place, and simply reroute AC out from the transfer switch, but I didn't want to rely on assumption alone. Thank you for your reply. It's very helpful!

 

[time2roll]

Yes. The only thing missing might be a 12v power supply as the RV probably runs on 12v for the DC side.

 

[Supervstech]

IDK, but when I read the title... I put the WTF words into the letters in the model number...

 

[culty]

Thanks @time2roll! Ok, I did some more investigation last night. It looks like I have the Inteli-Power 9200 series converter. I read up a bit on it. Is there a reason I couldn't keep that running to manage the DC side, since the battery bank for solar/growatt is isolated from the house batteries? I read some discussions online where people were advocating for keeping it, but since this is a new wrinkle I haven't fully wrapped my head around it yet (how it's wired, what the implications are, etc).

 

[culty]

IDK, but when I read the title... I put the WTF words into the letters in the model number...

??? this entire journey has been a series of WTF moments for me, but in the absolute best way one can hope.

 

[Supervstech]

??? this entire journey has been a series of WTF moments for me, but in the absolute best way one can hope.

Heh...
I pronounce it in my inner Thor voice...

 

[mkaye]

the converter needs to be disabled when running on the inverter otherwise you have a perpetual motion machine i.e. battery running inverter, inverter charging the battery.
you have to remember to turn the breaker off for the converter when running the inverter or install a relay that only powers the converter when you have shore power

 

[time2roll]

Yes the 9200 is a great converter to power the 12v side and will not cause a power loop with the 24v battery. Not sure this will be an efficient solution when off grid so maybe a switch to select if it should run or not depending on conditions. If the 9200 is on a separate breaker that will work fine as a switch. A DC-DC 24-12 converter might eventually be better.

 

[culty]

I've attached my wiring diagram showing the new wiring setup as best as I understand it. Is there anything here which is incorrect or missing?

Thanks!

 

[culty]

@mkaye Do you think this setup would fit the loop condition you were referring to? Is there anything else I need to include/check to ensure the converter is only handling the house batteries, and not looping back to the Growatt?

 

[culty]

Yes the 9200 is a great converter to power the 12v side and will not cause a power loop with the 24v battery. Not sure this will be an efficient solution when off grid so maybe a switch to select if it should run or not depending on conditions. If the 9200 is on a separate breaker that will work fine as a switch. A DC-DC 24-12 converter might eventually be better.

I presume you mean something like this Victron dc to dc converter, with the main difference being that the Victron will give me >92% efficiency vs the Inteli-Power's stated >80% efficiency rating, is that correct? Are there any other considerations I should be aware of?

 

[mkaye]

so the LFP batteries are only powering the inverter, which manages charging the LFP batteries and supplies AC (shore/inverter)
the LA batteries are powering the 12V side and are only charged when there is AC
no perpetual motion

 

[time2roll]

I presume you mean something like this Victron dc to dc converter, with the main difference being that the Victron will give me >92% efficiency vs the Inteli-Power's stated >80% efficiency rating, is that correct? Are there any other considerations I should be aware of?

The 92% is direct battery to battery. the Intel-Power gets 120v from the inverter that I assume loses another 10%.
Also when the 12v is full the Intel-Power will have a certain base load to maintain the battery.
See how it goes, take some measurements if the 24v battery seems to deplete sooner than expected.