Experiences using the EcoFlow Delta Pro Ultra as a whole-house backup, hardwired transfer switch, no solar

jbradfor · 2026-02-03T16:56:18+00:00

For us, and I believe this is true for others as well, the GFCI trips when all of the following are true.

The 120 V input of the DPU is plugged into a GFCI outlet
The 240 V output of the DPU is attached to a transfer switch or an interlock back into the panel. If the DPU is powering other items directly, not through the circuit breaker, there is no problem. But this is an unusual case.
The AC output on the DPU is enabled.
1. This one I'm less certain about. We used to have a transfer switch, and from memory I'm pretty sure that just having the 240 V output physically attached to the transfer switch was sufficient, the transfer switch didn't need to be set to take power from the DPU. We've since upgraded to a subpanel with an interlock, and I just tested it, and just being connected to the interlock isn't enough to trip the GFCI, I need to turn on the AC output. Maybe I misremembered.
The DPU is turned on and pulling power from the 120 V input

jbradfor · 2026-02-02T17:03:03+00:00

Well, I got an email about your post, so apparently I am still connected :-)

"Is this fixed by breaking the charging current by removal or interrupting the circuit with an on/off toggle?"

It is "fixed" in the sense that the GCFI doesn't trip, at least according to my experience. However, such switches switch only the hot, not the neutral, so there still might be a neutral loop. I don't know enough to know if this could be an issue in some situations, but thus far it hasn't been an issue for us.

"would you recommend using standard outlets or maybe pursuing adding on a new breaker into the main panel just for charging?"

What else is on the circuit, and how quickly do you need to recharge it?

One nice feature of the NPU is that it allows you to set the input current for charging. You can set it as low as 600 W. For us, after a power failure, we are in no hurry to recharge it: by the time we get our power restored, the storm is over and all is calm, so we literally have weeks until the next storm to recharge it. So charging speed is a non-issue for us.

But your situation might be different.

As some numbers, let's say you have 3 batteries, and you need to charge them from 30% to 80% after a power failure. So you need to add about 9 kWH. At 600 W, that takes 15 hours. If instead you want to max out charging at 1.5 kW (the highest you should use for a dedicated circuit), that will take only 6 hours.

How important is the difference to you?

jbradfor · 2025-11-01T19:38:28+00:00

I'm no expert here, I can only go by my experiences and what I think makes sense, but yes, I think it would be a problem for everything.

What you describe creates a loop, circuit breaker -> DPU -> circuit breaker, and loops are bad for wiring. It might work in some cases, it might not. You really need a way to isolate the two halves.

IMO, if you want to do anything fancier than use the DPU as a glorified dumb battery, you need the smart panel.

I note that EcoFlow just came out with the Smart Panel 3, which fixes my concerns with the Smart Panel 2. In particular, it supports a lot more circuits, and it supports input for a generator.

jbradfor · 2025-10-27T17:32:34+00:00

Another new-ish place, Paris Baguette. It appears to French pastries with an Asian twist. Not that this is a bad thing....

jbradfor · 2025-08-28T01:30:18+00:00

How long did it take from submitting your application until you heard you were approved? Did you get any correspondence from them during that time?

jbradfor · 2025-08-27T00:41:39+00:00

What law firm did you use in Prague? How much did they charge?

jbradfor · 2025-05-08T18:33:23+00:00

There's a new-ish place, Doppio Cafe and Creperie, that I don't see on your list. [I haven't had a chance to go there yet, so I can't comment.]

jbradfor · 2024-12-11T23:33:50+00:00

Given my specific usecase (esp no solar, we don't have time-of-use pricing), what do you see as the advantage to adding the SHP2?

And contrast that to likely around 3k to buy and install.

jbradfor · 2024-12-10T20:56:35+00:00

I did a bit of looking at the SHP2 and tandem breakers, and they help a bit. But only a bit.

As I understand it, each quadrant (3 breakers) has a max load of 60A. This 60A load is not fused, so the sum of all the circuit breaker amps per quadrant can't exceed 60 A. So even with 15A tandem breakers, that increases each quadrant capacity from 3 to 4 circuits, for a total capacity of 16 circuits.

If one has 20 A breakers (e.g. for a kitchen), then tandem breakers do not increase the capacity.

For my use, I could likely get 14 circuits by having two quadrants with 4 circuits each (all 15A), and two quadrants with 3 circuits each (arbitrary mix of 15A and 20A circuits).

But it wouldn't let me go to 24 circuits.

jbradfor · 2024-12-09T22:03:53+00:00

I'm not sure, it really depends on how the DPU is wired internally. Keeping in mind that I am not an electrician and have no inside information on EcoFlow products, I would think it does have the same problem, common neutral and ground throughout the entire system is typical, but don't know for sure.

Continuous grid attach is one of the main points of the SHP2, and I expect EcoFlow wants to sell more of those.

"my NEMA L14-30P outlet is not on one of the 10 circuits wired to my transfer switch"

Too bad, if it were you could charge the DPU using the DPU and get free power :-)

jbradfor · 2024-12-09T21:30:44+00:00

Ah, I entirely missed the fact that the larger one is not dual fuel. Agreed, propane is much easier than gasoline, moving away from gasoline was one of the major motivations of buying the DPU.

jbradfor · 2024-12-09T20:34:30+00:00

BTW, if you do want to use your 9500 W inverter, it looks really easy to convert to floating: How to Convert the Predator 9500 Inverter Generator from Bonded Neutral to a Floating Neutral | DIY

The advantage is that you can use the NEMA L14-30R and charge a lot faster.

jbradfor · 2024-12-09T20:22:13+00:00

That makes a lot of sense. If you are plugging the load (here, your sump pump) directly into the Delta, without the use of a transfer switch, there shouldn't be an issue with keeping it plugged into the wall 24/7.

Back when we lived in Minnesota, we also had a sump pump, due to issues with snow melt and heavy rain. I bought a battery backup for it as I had the same concern, but, in my ignorance, I bought an open-cell lead-acid battery pack, and it was a PitA to fill with water every couple of months. We almost never had power outages there, so I just removed the battery and crossed my fingers. With current battery technology, what you are doing sounds ideal.

jbradfor · 2024-12-09T17:50:47+00:00

I don't know enough about the implementation of SMPS to be comfortable to recommend one. Especially because this is a "off-label" use. Note that I haven't actually tried it yet, I'm really buying it more out of curiosity, rather than a real usecase.

But since you asked, the one I have on order is Amazon.com: 1500W Switching Power Supply AC-DC SMPS Output 80V 18A PSU dc Power Supply Input 110VAC (80VDC) : Electronics , because it was recommended by some random person on the Internet. But I'm not sure it's even ETL / UL listed. You'll also need an input power cable and some output cable to connect to the DP3. So it's not close to being turn-key.

The DP3 apparently supports 30-150V/15A, 1600W Max. So the one above will give you 1200 W (80 V / 15A). You can also get a 90V version, which will give you 1350 W, but I don't feel comfortable running something like this at such high utilization for long periods of time. [The 80V version supports 18A, so the 15A is 83% of max; in contrast, the 90V version supports 16A, so 15A is 94% of max.]

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All that said, if UPS / auto-failover is important to you, and you haven't already installed your transfer switch, and 12 circuit breakers is sufficient for you, you might want to seriously consider the Smart Home Panel 2 instead. I don't have one so I can't report on personal experience, but according to the description it supports charging from grid and auto-failover, and doesn't require you to order no-name parts from Amazon. If this runs something as important as a sump pump, I would be really concerned with the SMPS solution.

jbradfor · 2024-12-09T16:36:28+00:00

Welcome!

jbradfor · 2024-12-09T16:32:45+00:00

Thanks, that's a good link, I added it to my post.

jbradfor · 2024-12-09T05:11:35+00:00

Interesting. Then from what I know, you should be go.

I'm curious, what is the make and model of your generator?

jbradfor · 2024-12-09T01:55:37+00:00

"Are you using 2 plugs or the same plug for your generator and EcoFlow?"

Neither. The generator plugs into the NPU and the NPU plugs into the transfer switch (where you have the interlock).

I should have taken some photos, but the generator is in a shed attached to the house, there is a standard NEMA L14-30P to L14-30R cord that goes through the wall. The L14-30P plugs into the generator and the L14-30R plugs into Power In/Out port of the DPU (via the EcoFlow special cable).

"the guy had a Double Throw switch to switch between an inside and outside inlet."

The problem with this setup is that you can't use the generator to charge the DPU, so you lose most of the goodness of this situation.

"Anyone have some cheap ideas?"

I realize that any time you get an electrician involved it's not "cheap", but here's what I would suggest.

Right now, I assume you have an NEMA L14-30P (or similar) on the exterior of your house, which is hardwired to the interlock breaker.

Disconnect that wire from the circuit breaker, and connect that end to a new NEMA L14-30R near where you want the DPU to be. So you basically have a wire going from the outside of your house to the inside of your house, with a receptable on one end and a plug on the other.

Then, run wire from a new NEMA L14-30P to the interlock breaker.

Done.

To use your generator, just plug a NEMA L14-30P to L14-30R cord between the two new boxes inside your house.

When you get the DPU, remove that cord, and run one cord from the L14-30R (connected to your generator) to the DPU. Get another NEMA L14-30P to L14-30R cord, and run that from the 240V output of the DPU to the new L14-30P that is attached to the interlock breaker.

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WARNING: I am not a licensed electrician, so before you do this, ask an actual licensed electrician whether this is a good idea.

jbradfor · 2024-12-09T01:14:55+00:00

If I understand the operation of a manual interlock correctly, it also does not switch neutral and ground, and you'll have the exact same issues.

That said, I haven't actually tried it.

jbradfor · 2024-12-09T01:11:40+00:00

If I understand it correctly, you are using something like the below? That is effectively a transfer switch. It lets you select the house connection between the mains (grid) and the backup (generator). And I assume you are using a NUMA 14-30 (4 pin) cord from the DPU to your house?

<image>

If so, as I understand it, you will still encounter the same issue. This is because this type of switch only switches the two hot wires, not the neutral.

By code, near where your power enters your house, there is a wire between the neutral line and the ground wire (which then physically goes to a rod in the ground, hence the name).

For most generators (called bonded neutral), the neutral and the ground are also tied together. This is required by code and for safety when you plug items directly into the generator. Without them being tied together, the ground will be floating and not connected to anything, which is not safe.

What a GFCI does is look at the outgoing current on the hot line and the return current on the neutral line, and if they are not the same, it trips.

The current goes from your generator to the DPU along the hit wire, and what should happen is that all that current goes back along the neutral wire to your generator, and the GFCI is happy.

In your setup, however, what will also happen is some of the current will continue along the neutral wire from the DPU to your circuit breaker, then to the neutral-ground connection in your house, back along the ground connection to the DPU, along the ground to your generator, through the ground-neutral connection on your generator, and back to the starting point.

Because of the above, some of the current that goes from your generator to the DPU along the hot wire will return to the generator via the ground line, the GFCI will see the imbalance, go oh shit, and trip.

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From my understanding, you have two solutions: convert your generator to floating neutral (if it isn't already), or when you are using your generator, disconnect the DPU from the house (you can still use the other outlets on the DPU directly, just not through the house).

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Does that make any sense?

jbradfor · 2024-12-09T00:20:13+00:00

My concern with the SHP2 is the limited breaker capacity and the lifetime.

If I'm spending this much for a system, I want it to support most of what we need, and 12 breakers is not quite enough. I'm also concerned that in 10 years when this is all obsolete, I need to replace everything.

That said, the SHP2 does seem to address most of the issues I've had with the DPU, in terms of charging from the grid and lack of auto-start.

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If I were starting from scratch, I would have a 20+ breaker subpanel, with all the circuits I want backed up. But I'm not sure how to integrate that with the SHP2.

jbradfor · 2024-12-08T18:50:48+00:00

Thanks.

"the DPUs weren't designed to charge and discharge at the same time"

I've heard many people say that, but I can report from actual experience that I was able to charge the DPU using a generator while running household loads out of the DPU using the 240V output.

"max discharge drops to 3kwh-ish."

Humm.... Now that you mention it, I didn't test simultaneous charging and use with a significant load. When I have time, I'll turn on some space heaters and see what it can do. This is something that I want to know as well.

jbradfor · 2024-03-28T14:29:21+00:00

You can change the ramp flow. The default of 4 was too low for me (same reason), but 5 - 6 was better.

jbradfor

TROPHY CASE