Growatt spf 3000 es, utility generator and grounding

polygon

New Member
Joined
Dec 3, 2021
Messages
8
Hello I saw a read a lot of post about grounding and using a generator but i am now lost and not really sure what i should do.

I have a growatt spf 3000 es with a solar panels and a generator no battery at this time.

if i use the solar panel only it work. if i use the generator only it work. But if i use the gen with solar priority the gfci trip on generator, no error on the inverter. (it worked for a few hour without any problem and then just trip)

here a pic how all this is connected.

any idea what i am doing wrong?

edit I found out that none of the breacker are actualy triping the generator go on fault when solar is activated, maybe i am understanding wrongly how it work: can i get ex 600 watt from panel and the missing 400w from generator?
Untitled.png
 
Last edited:

FilterGuy

What, me worry?
Joined
Nov 26, 2019
Messages
5,630
Location
Los Gatos CA
A few questions:

1) Is it a Growat spf 3000 LVM ES? (120 V North America?)
2) Do you know if the generator has a Neutral-Ground bond? (With the generator not running and everything unplugged, check continuity between Neutral and ground)
3) On the side of the unit there are two stickers. the bottom sticker has "PN=xxxxxxxxxxx" What does your sticker say for PN?
 

polygon

New Member
Joined
Dec 3, 2021
Messages
8
A few questions:

1) Is it a Growat spf 3000 LVM ES? (120 V North America?)
2) Do you know if the generator has a Neutral-Ground bond? (With the generator not running and everything unplugged, check continuity between Neutral and ground)
3) On the side of the unit there are two stickers. the bottom sticker has "PN=xxxxxxxxxxx" What does your sticker say for PN?
Hello Sorry for the late reply.

1. yes it is a growatt spf 3000 lvm ES 120v / 48v
2. i tested the generator generac gp2200i and I couldnt find continuity between neutral and ground
3. pn is sksl00 0009401 sn endet with DO2

i installed a pylontech us 3000 and it work perfectly if i turn on the generator it will charge the baterie but if the panel are on it will go in fault.

thank you
 

FilterGuy

What, me worry?
Joined
Nov 26, 2019
Messages
5,630
Location
Los Gatos CA
OK.
  • The generator is not tying neutral to ground.
  • You have an older model growatt that does not do any bonding.
Therefore, it appears the system is floating and needs a Neutral-Ground bond added.
A couple of questions:
1) In your diagram is the red or black the Neutral on the AC circuits?
2) Do you ever expect to plug this into the grid or shore power?


Here is some info on the grounding and bonding on the growatt:

1642113953872.png

In your case there is no N-G bond anywhere in the system so one will need to be added.
 

Librelec

New Member
Joined
Jan 9, 2022
Messages
26
Location
AUSTRALIA
@FilterGuy is it common practice for a generator supply to be protected by a GFCI?

Also, I'd suggest checking for continuity between ground and neutral (at the AC Out panel, or the AC Out terminals on the inverter) during normal operation (generator+pv) AND during battery (or battery+pv) operation.

the neutral to ground bonding *might* change between the different settings.

edit: also, where I'm from, installing a grounding rod in this situation (completely off grid/supplied by generator) is considered useless and actually more unsafe, than not installing the grounding rod/having a floating system.

is that different elsewhere?
 
Last edited:

FilterGuy

What, me worry?
Joined
Nov 26, 2019
Messages
5,630
Location
Los Gatos CA
@FilterGuy is it common practice for a generator supply to be protected by a GFCI?
'Common' is a rather loose term. Some generators have GFCI, Some don't.

Similarly, some generators have an internal N-G bond.... but most generators in the us that are under ~4K do NOT have a N-G bond.

Given the thread
Also, I'd suggest checking for continuity between ground and neutral (at the AC Out panel, or the AC Out terminals on the inverter) during normal operation (generator+pv) AND during battery (or battery+pv) operation.
Yes....but no. If the system is powered up, how are you checking continuity? Putting an ohmmeter on it will fry the ohmmeter. What you want to do is check voltage between neutral and ground. If the voltage is zero or near zero between neutral and ground there is one (or more) N-G bond. More than one N-G is a problem. If there is more than one N-G bond, there will be a current on the ground wire between the inverter and the Generator or Grid box.

also, installing a grounding rod in this situation (completely off grid/supplied by generator) is considered useless and actually more unsafe, than not installing the grounding rod/having a floating system.
Well..... I guess everyone has a different point of view on this. I personally think tieing to the ground and not letting it float can be made very safe *and* there is less chance for equipment damage.
 

Librelec

New Member
Joined
Jan 9, 2022
Messages
26
Location
AUSTRALIA
'Common' is a rather loose term. Some generators have GFCI, Some don't.

Similarly, some generators have an internal N-G bond.... but most generators in the us that are under ~4K do NOT have a N-G bond.

Given the thread

Yes....but no. If the system is powered up, how are you checking continuity? Putting an ohmmeter on it will fry the ohmmeter. What you want to do is check voltage between neutral and ground. If the voltage is zero or near zero between neutral and ground there is one (or more) N-G bond. More than one N-G is a problem. If there is more than one N-G bond, there will be a current on the ground wire between the inverter and the Generator or Grid box.


Well..... I guess everyone has a different point of view on this. I personally think tieing to the ground and not letting it float can be made very safe *and* there is less chance for equipment damage.
ok I think I misunderstood the GFCI. I assumed the above poster installed a GFCI on the cable between inverter and generator.

but now I'm assuming the generator has an inbuilt gfci?

if this is the case, doesn't there need to be an N-G bond for that GFCI to operate?

apologies, if I gave bad advice - I've just never blown up my multimeter testing between N-G.

however checking the voltage (for 0V) is a better test.

I won't comment any more on the grounding rod - that could just be different rules for different regions.
 
Top