I don’t understand the behaviour of my Hybrid inverter. Please help.

Hi, I’m new to this so please forgive me if this is a silly question but…

I had a 10 panel solar system installed with Growatt 5kw hybrid inverter and 6.5kwh Growatt battery.

On day 1 the battery was off (waiting for leads) so during the day I was running on solar only. My smart meter said I was using 0kw from the grid, yay! Just as I expected my panels were running my house.

Today the battery was connected up. It all seems to be working well however during the day despite having loads of sun which was powering my house and charging the battery I notice my smart meter was saying I was using about 100w from the grid.

The same was true in the evening when my panels shut down, and I was using the battery only.

It seems everything is working however I’m now always pulling between 50 and 100w from the grid whether or not I have enough solar or battery power. Do you think maybe the CT clamp is faulty or is this normal? To confirm also the ShinePhone does not show any grid input.

I don’t understand what’s going on. Please help.

I would say it's normal, it's staying synced with the grid so it can quickly bypass. "idle consumption"
What mode are you using, SBU?

I'd also verify it with a clamp meter, then flip the grid input off and see if there is an additional load on the DC side.

I'm sure growatt experts will chime in with better info.

Which model Growatt?
If I were to guess. I would say that it's a Growatt SPF-5000-ES (Offgrid, not hybrid) , and it's in SUB mode.

My inverter is the hybrid (sph-up series). The app shows the inverter is in ‘on-grid mode (load first)’ which I believe is the default mode.

My 18Kpv shows the same behavior. I've always chalked it up to "checking in" with the grid. Sometimes it's exporting, sometimes it's importing. All in all, I think it tends to zero out over the course of the day.

If there's a switch or setting that will turn this off - without impacting my system, I'm eager to hear it. I've finally got everything working as I expect and I'm hesitant to even walk near the thing, much less start tweaking the settings!

digitalfm said:

My inverter is the hybrid (sph-up series).

Click to expand...

Sorry, I've never heard of that one.
I don't think that I can help. But, I hope you find your answer.

To confirm my inverter is a Growatt SPH 5000 Hybrid.

I do see the installer cut the CT clamp cable in half, and used a cat 5e cable to extend the length. It's using wago clips to make the connection. Are the 2 wires inside the CT Clamp cable reversable? What I mean if they got switched when he added the extension would that cause inacurate readings?

digitalfm said:

What I mean if they got switched when he added the extension would that cause inacurate readings?

Click to expand...

It would reverse the readings.
(Import vs export)

digitalfm said:

It seems everything is working however I’m now always pulling between 50 and 100w from the grid whether or not I have enough solar or battery power. Do you think maybe the CT clamp is faulty or is this normal? To confirm also the ShinePhone does not show any grid input.

I don’t understand what’s going on. Please help.

Click to expand...

TADTS! Seriously though... for a grid-tied system I would expect a bit of meandering around 0W as the inverter tries to keep the import/export balanced, but certainly not a constant draw of 50 to 100W.

From what you are saying, it sounds as though the Growatt thinks it is balanced (as reported by your Shine Phone app) but clearly not from the smart meter readings.

First call should be to get your installers back to fix it.

I recall some other threads about Growatts having this issue - see links below. In one case the installers didn't use a twisted pair cable, in the other (IIRC) it was fixed by using a power meter rather than directly connected CT clamp.

Thanks @SeaGal . I do see the installer has not used a twisted pair on the cat 5 cable, just used the brown and orange wires. There's also no shielding where the wires are connecting. I'll rewire and see what happens.

I just spoke to Growatt who didn't know either but they tested my system (which I could see) and said it was running perfectly. They of course can't see my smart meter but they at least confirmed the inverter and battery was working well. To be fair they were really helpful.

Some hybrids do have the facility to draw a minimal load from the grid when in no-export mode (Deye certainly do).

The idea being that any minor exports that may occur during load changes are absorbed by the constant import so that the inverter never, ever exports (some grid operators seem to get most out of joint if there's even a tiny bit of exported energy).

If this is the case you should be able to turn it off.

Does the Growatt have a "CT calibrate" feature, maybe that would help match the two readings.

But I'm with the above "get the installer back" comment, they ought (yeah, I know) to know how their system works.

digitalfm said:

I do see the installer has not used a twisted pair on the cat 5 cable, just used the brown and orange wires.

Click to expand...

Doh... Why does that not surprise me . Sounds like the exact same issue that @radiomean had 2 years ago.
Fingers crossed and keep us updated.