growatt 5000 US model - grid backed up self consumption - connection to main service panel

pulper11

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hoping someone can help me here or at least lead me in the right direction. i'm getting pretty confused.

background:
electricity usage: approx 11kw/year
live in southeast michigan

original plan:
mount solar panels on my detached garage. one side of the roof points directly south. run PV array wire to house (already have conduit in ground connecting garage to house so either fit extra cables in the conduit or replace current cables in the conduit with the pv array cable).
use a subpanel in the house and slowly, as my array grows, move more from the main panel to the subpanel to reduce my electricity usage.

planned main equipment:
growatt 5000 (US model).
growatt transformer
six 375 watt REC solar panels to start.
one 48V 100Ah server rack battery to start.

possible plan update:
after some reading and research, i'd like to do what i believe is called "Grid backed up self consumption". using the same equipment above, i'd like to connect the growatt in such a way that it utilizes solar first, then batteries, and then grid. i've read the growatt can handle this. however, I have no idea how i would connect the AC out on the growatt to a main service panel to feed power to the house.
My electrician previously installed an interlok kit on my panel b/c of grid blackouts, and it works well with my generator. however, that is a manual switch that requires turning off the main power from the grid first to avoid back feeding the grid.
with the solar, i believe the growatt handles all of this automatically with no backfeed to the grid and prioritizes based on the settings.

My electrician is great. However, i do not believe he is very knowledgeable about solar products. however, if i'm able to explain to him what i'm trying to do with some specifics, it would not be a problem for him. trouble is, i am so confused in reading about the connection to the service main panel that i can't explain it, and he also might be nervous about back feeding the electricity and might need reassurance.

Any help would be greatly appreciated. Also, if you have any suggestions about equipment changes, please let me know. six of the REC panels in series had a VOC greater than allowed by many other all-in-ones, which is one of the reasons why the 5000 is what i'm looking at. Thank you!
 

MrM1

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Look at the Reliance Controls Pro/Trans 2 series. Biggest issues will be with how to handle neutral and ground and bonds

 

pulper11

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Thanks for your reply. This seems that it would help with my original plan. However, i don't think it helps with my possible plan update (unless i'm reading it wrong).
 

Tecnodave

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I will comment only one part of your project, you cannot have the P.V. wires in the conduit with anything else if you will be seeing the inspector, a no-no under the NEC
 

Quattrohead

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Get an inverter meant for the USA, not cheap backdoor hacked up method unit. Too many safety issues with our weird split phase system.
 

pulper11

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Get an inverter meant for the USA, not cheap backdoor hacked up method unit. Too many safety issues with our weird split phase system.
Thanks. I'm planning on purchasing the US version of the growatt 5000. Hope this satisfies your suggestion. Here is the link:
 

Tecnodave

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See if they will provide documentation that that unit is “listed to U.L.1741” by a U.S. OSHA NRTL...

Those are the exact wording that your building inspector....and insurance company will need to see

”Listed by ETL to U.L.1741”

OR

”Listed by U.L. to U.L.1741”

OR

“Listed by T.U.V. to U.L.1741”


words such as

Tested to U.L. 1741

Certified to U.L.1741

DO NOT MEAN SQUAT.

Jack’s Smoke cannot list to UL1741

Franks Barbecue cannot list to U.L. 1741

Joe’s Auto cannot list to U.L.1741

IT MUST BE LISTED BY A U.S. OSHA NRTL

If you buy a non listed device your building inspector will not be happy

Nor will your insurance company....

And you risk severe shock
 
Last edited:

pulper11

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Is the issue with my scenario and ul listing for the inverter bc I am planning on back feeding my panel? just To clarify, I am not trying to do any net metering.

if so, if I just used a separate sub panel as previously suggested then would The ul listing be required?

it appears the only growatts with ul listing are the hybrids with net metering capabilities. The lv6548 is ul listed but it is significantly less than the 5000 max voltage of the array.

thanks for bringing this to my attention.
 

Tecnodave

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Anything connect to your power needs to be U.L. listed, some people will disagree with me about that but I do have a pile of gear that I was paid to remove due to no U.L. listing, any building on grid or off grid needs U.L. listing. Some places will not know, but here in California you will get tagged for that and if you do not comply a red tag is next, that removes the occupancy permit as well as invalidates your insurance
 

Quattrohead

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With a little more money you can get a UL listed inverter that does not need a transformer.
The Growatt 5000ES is a fantastic unit, it just ain't for the USA market except certain instances where it can operate safely.
Running an AC compressor stand alone would be one good example, straight 240v load.
 

pulper11

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With a little more money you can get a UL listed inverter that does not need a transformer.
The Growatt 5000ES is a fantastic unit, it just ain't for the USA market except certain instances where it can operate safely.
Running an AC compressor stand alone would be one good example, straight 240v load.
Thanks for the post. I’m wondering however if i am confused since the link I posted above to what signature solar refers to as a US model still isnt safe For the US? The reason I listed a transformer in my original post was to get 120 and 240 out of the 240 US model, not to try to make the growatt safe for the US. I’m assuming I’m misguided here so please be kind!
if you could Provide the names of some other ul listed models, that would be great. The lv6548 sounds great but it (as mentioned) is limited in max V and also is close to twice the price over the growatt and I would need to purchase two to get 120/240.
I don’t mind spending a bit more but that adds up.
please let Me know if I’m wrong. Thanks.
 

Tecnodave

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During U.L. certification up to 10kv. is applied to every line voltage terminal to test for lightning strike protection, This is not applied to the neutral terminal as lightning normally strikes the live conductors only , not the neutrals which are generated at the utility transformer next to or near your home. Using a unit that was designed for european grid on the american grid results in putting live voltages possibly containing a spike from a lightning strike a 1,000 miles away on the neutral line which was designed to be near ground potential can result in the unit shorting that spike and causing damage which may result in fire and shock hazard. . I have done destructive testing on units and the fail mode can be dramatic. I personally had a Fluke 77 DVM which is not rated to use on live power wires fail in a rather dramatic mode when there was a lightning strike many miles away in the Sierra Nevada mountains and traveled 800 miles across the state and destroyed the Fluke DVM in a cloud of smoke while I was up 24 feet with the meter in my hands. Now I will only use a meter rated IEC 1010 cat IV which is rated for 10 kv. spike without damage, (Fluke 87V) . You do not really want a meter exploding in your hands when checking power at the utility company masthead, nor a power unit on the mains causing any kind of fail mode. The “startle factor” could well have caused me to fall from way too many feet to be comfortable with. I was wearing my Klein safety harness so I didn't fall.

The power grid is one huge “sky spark attractor” and anything attached to it is a pathway to you on it’s way to ground

The codes were written as the result of fail modes that burned down buildings and injured persons. U.L. listing does make things cost more but also is a guarantee of design safety as every known possible fail mode is explored.

Personally I will not use non U.L. rated equipment for the safety factor that U.L. listing conveys, nor will I sell it, service it or install it.
 

pulper11

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looking more at the ul-listed lv6548. the lv6548 has dual pv inputs, and a pv input of 250v (VOC). If i have one series string at 200V and say another at 150V (not sure if they have to be the same), do i need a combiner box or can i just use the two different pv inputs on the inverter?
 

kjswiley

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Thanks for the post. I’m wondering however if i am confused since the link I posted above to what signature solar refers to as a US model still isnt safe For the US? The reason I listed a transformer in my original post was to get 120 and 240 out of the 240 US model, not to try to make the growatt safe for the US. I’m assuming I’m misguided here so please be kind!
if you could Provide the names of some other ul listed models, that would be great. The lv6548 sounds great but it (as mentioned) is limited in max V and also is close to twice the price over the growatt and I would need to purchase two to get 120/240.
I don’t mind spending a bit more but that adds up.
please let Me know if I’m wrong. Thanks.

I too have the Growatt 5000-ES, and wanted to add to the votes for another inverter since you are in the US. I didn't research the MPP LVXXXX inverters as no one had them when I was buying, but I think you are on the right track as they are a popular choice here.

The problem is the transformer needed. This is completely unnecessary if you buy an inverter designed for North America from the start. Someday that transformer could fail, and it could destroy your 120V devices. I love the inverter, it works great, but had I understood what it meant ahead of time I would have gone another direction. In the end it is a work around to use a system that wasn't designed for North America, and it is not a very good work around at that.


My understanding (perhaps there are real changes to the "US version but I do not believe this is so) the "EU" version has the screw bonding the neutral to ground in the inverter which is needed in Europe and many other places in the world. The "US" version had the board changed so this bond does not happen, but only if you bought from signature solar, but people buying from Amazon or other online vendors were buying versions with the screw included. No units have any markings or stickers differentiating the two designs, they are all labeled as 5000-ES, thus they will be releasing the "US" version officially to fix this labeling issue. That is pretty much the only difference, these are really not made for North America (probably not a great idea for any of the Americas). I am pretty sure my "Growatt 5000-ES" is identical to what will sold as the "Growatt 5000-US", you can read ALL about it in the following thread.

Safety hazard w/ Growatt 5000ES (European version) when connected to American grid
 

Tecnodave

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looking more at the ul-listed lv6548. the lv6548 has dual pv inputs, and a pv input of 250v (VOC). If i have one series string at 200V and say another at 150V (not sure if they have to be the same), do i need a combiner box or can i just use the two different pv inputs on the inverter?
On units that have dual inputs generally they would have two MPPT front ends, each optimizing for the string attached to it, but some have only one MPPT front end with two separate fused inputs. This is the question to ask the dealer. If they cannot state that with clarity, then you have a sales person selling you an item. It is much better to find someone who has very intimate knowledge of the product. With two seperate MPPT processors the unit will be able to optimize the panel string to best advantage. I do know for certain the SMA America “Sunny boy” does indeed have seperate front ends, if fact they have two seperate inverters which will optimize each string. These are very useful where you have one array facing east of south and one array facing west of south. These units are very much specialized for this situation. The models that have the model numbers such as TL3000US have two seperate 1500 watt inverters for a total of 3000 watts at peak of preformance, Other models from SMA America have a model number such as TLXXXXUS all have two separate inputs and inverters, These SMA units are grid tie inverters that are batteryless. This is only an example of this. SMA is a German company but these units are very much specialized for the American split phase market

I would not hesitate to recommend SMA America, but being quality German units they will far outlast anything coming out of China.

In all honesty I must state that I would not buy anything from China, It is inferior quality and will not last nearly as long as U.L. listed products. My system is >90% American using MidNite Solar, Magnasine, Victron, Exeltech, Samlex, etc. Have had one power failure when a spare inverter made in Tiawan failed after 12 years use, That was a Cotek SK-1500 inverter, There are a few asian units that are good values for the money. But only a few, I just named one.
 

MrM1

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@Tecnodave what about the midnite solar DIY for this application? I know, just a re-branded version of a few others, but isn't its actually UL listed with great customer service in the US? Although it's not low frequency.
 

pulper11

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My understanding (perhaps there are real changes to the "US version but I do not believe this is so) the "EU" version has the screw bonding the neutral to ground in the inverter which is needed in Europe and many other places in the world. The "US" version had the board changed so this bond does not happen, but only if you bought from signature solar, but people buying from Amazon or other online vendors were buying versions with the screw included. No units have any markings or stickers differentiating the two designs, they are all labeled as 5000-ES, thus they will be releasing the "US" version officially to fix this labeling issue. That is pretty much the only difference, these are really not made for North America (probably not a great idea for any of the Americas). I am pretty sure my "Growatt 5000-ES" is identical to what will sold as the "Growatt 5000-US", you can read ALL about it in the following thread.

Safety hazard w/ Growatt 5000ES (European version) when connected to American grid
I saw Will's latest video regarding the 5000ES vs US. It appears that you are right. I will not buy the Growatt 5000. Thanks for your post.
 

pulper11

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Just purchased the LV6548 from Ian at Watts247.com. Called him up first and spoke with him about a couple of questions, including what @Tecnodave suggested. Very helpful. Glad I posted here and glad people were friendly and helpful to a newbie like me. Appreciate it. Steered me away from what could have been a disaster situation with the Growatt.
 
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