Question About EG4 18kpv Grid Connection

[JoshN123]

Hi all,

I'm planning on installing a residential solar system on my house with the EG4 18kpv inverted and powerwall. Upon reviewing the manual, I found this diagram.


Prior to viewing this diagram, I was planning to install the system like this:


I'm trying to understand the need for the Feeder Tap and Manual Transfer Switch. Doesn't the EG4 18kpv have a built in automatic transfer switch? Can I run my main service power directly to grid inputs on the EG4 18kpv and run wire from my Load directly to my main panel?

Thanks

 

[BraydenFromEG4]

The inclusion of a manual transfer switch is helpful in the event that your solar system needs to be worked on (maintenance, expansion, etc.) but you don't want to lose power to the main load panel since you can just bypass the ESS with grid power. It's not a necessity, but that extra preparation goes a long way if you are to ever modify your system.

 

[JoshN123]

The inclusion of a manual transfer switch is helpful in the event that your solar system needs to be worked on (maintenance, expansion, etc.) but you don't want to lose power to the main load panel since you can just bypass the ESS with grid power. It's not a necessity, but that extra preparation goes a long way if you are to ever modify your system.

Thanks Brayden. So my plan is feasible, but I would have to completely shut down power to my main panel in order to work my solar system.

I've also been watching this video which might be a better alternative than my drawing while maintaining the benefit able to maintain power to the main panel while working on ESS. Here's the youtube link:

It's a long video from a master electrician. From 20 minutes to 28 minutes, he explains connecting both grid and load to his main breaker panel using an interlock breaker to prevent backfeeding the grid when the power is down. He installs the interlock at 59:30.

Is this a suitable way to wire the system?

 

[JoshN123]

The inclusion of a manual transfer switch is helpful in the event that your solar system needs to be worked on (maintenance, expansion, etc.) but you don't want to lose power to the main load panel since you can just bypass the ESS with grid power. It's not a necessity, but that extra preparation goes a long way if you are to ever modify your system.

Here's a drawing to make it simpler.

 

[BraydenFromEG4]

It should accomplish the same goal, but whether or not it's allowed is likely up to your local AHJ. Interlocks are a pretty common way to implement a transfer from what I've seen. Not sure how easy/hard that is to get through an inspection though.

 

[bfaubion]

I thought I'd piggyback on this conversation and ask for some advice since I'm also looking at this setup as well. Same meter/200 amp main breaker setup, and then using that same EG4 diagram. The 2-pole manual transfer switches are quite expensive and BIG. From what I understand, the breaker interlock performs the same function. I have a few questions as well as I'm inventorying parts.

1. Assuming breaker interlock is code compliant for my area, are the breaker interlocks any less or more safe than the manual transfer switch?
2. About the feeder tap and breaker, what is the purpose of that 200 amp feeder tap breaker since there is already one coming from the main panel?
3. The lockable AC disconnect switch - I guess that's the 2-pole fused disconnect. Could I skip that as a separate element and just have 1 panel that has the main AC line in, with 2 200 amp breakers, one for the inverter, and one for the inverter bypass to transfer/interlock? (I've included a diagram here to show what I mean)
4. How important are surge arrestors for the 18Kpv inverter, could I skip those?

 

[DIYrich]

Assuming breaker interlock is code compliant for my area, are the breaker interlocks any less or more safe than the manual transfer switch?

Does the same thing. The Breaker Interlock allows both side to be off, whereas I believe a MTS always has one side or the other connected.

About the feeder tap and breaker, what is the purpose of that 200 amp feeder tap breaker since there is already one coming from the main panel?

On/Off switch to the 18kPV. If you ever need to take it off-line for service, you flip the breaker, and the grid input line goes dead. Nice and easy.
Note: Same for the breaker on the Load Line.

The lockable AC disconnect switch - I guess that's the 2-pole fused disconnect. Could I skip that as a separate element and just have 1 panel that has the main AC line in, with 2 200 amp breakers, one for the inverter, and one for the inverter bypass to transfer/interlock? (I've included a diagram here to show what I mean)

I think that is a code question.

How important are surge arrestors for the 18Kpv inverter, could I skip those?

cheap insurance. Put one on the grid side between Meter and Feeder Tap on your diagram. Or, in the Feeder Tap.

 

[JoshN123]

The inclusion of a manual transfer switch is helpful in the event that your solar system needs to be worked on (maintenance, expansion, etc.) but you don't want to lose power to the main load panel since you can just bypass the ESS with grid power. It's not a necessity, but that extra preparation goes a long way if you are to ever modify your system.

I'm looking into downsizing my system. Is it possible to substitute the EG4 6000xp (potentially two) and do the same wiring with grid and load wired to my main panel using an interlock breaker so that load and main service are never on at the same time?

To clarify my question, does the Grid connection work both ways on the EG4 6000xp like it does on the 18k? Of course, I'll need to downsize my solar panels accordingly. If my power requirements are higher than the 6000xp can supply, will it shut down or would the main service just provide the power?

I'm aware that EG4 6000xp does not allow you to transfer energy back to the grid. Would it still shutdown like the 18kpv does if grid input were to cease?

 

[DIYrich]

To clarify my question, does the Grid connection work both ways on the EG4 6000xp like it does on the 18k?

no. Input only from grid. No export.

. If my power requirements are higher than the 6000xp can supply, will it shut down or would the main service just provide the power?

Switch to grid.

I'm aware that EG4 6000xp does not allow you to transfer energy back to the grid. Would it still shutdown like the 18kpv does if grid input were to cease?

If no grid, no pv, no battery, there is no energy, so it will shut down.

 

[JoshN123]

no. Input only from grid. No export.


Switch to grid.


If no grid, no pv, no battery, there is no energy, so it will shut down.

Thanks for the response. So Grid is only an import circuit and Load is only an export circuit. If that's the case, would I be able to wire both Grid and Load into my main panel and have both circuits active at the same time?

Would this create any risk of unintentionally back-feeding the grid in a grid down situation?

I would think that if the Load is running electricity into the panel and the main service breaker is open, there would be a danger in back-feeding the grid via the Load. Is this correct? If not, could you provide a brief explanation? Thanks!

 

[DIYrich]

would I be able to wire both Grid and Load into my main panel and have both circuits active at the same time?

No

Would this create any risk of unintentionally back-feeding the grid in a grid down situation?

Yes. Even worse. If grid is down, you will energize your neighbors too. Power can go from Load output to the grid line. Also inverter is probably not designed to see power on the load line, and might fight the grid.

 

[JoshN123]

No


Yes. Even worse. If grid is down, you will energize your neighbors too. Power can go from Load output to the grid line. Also inverter is probably not designed to see power on the load line, and might fight the grid.

Noted. I can not run Load and Grid to the same panel at the same time without back-feeding the grid in a grid down situation.

If I purchase two EG4 6000XP's and parallel them, I know this would double my output from 6000W to 12000W. Does this also double the grid passthrough from 50amps to 100amps, provided that I wire both Grid's to my incoming service panel and both Load's to a secondary critical loads panel?

 

[JoshN123]

I thought I'd piggyback on this conversation and ask for some advice since I'm also looking at this setup as well. Same meter/200 amp main breaker setup, and then using that same EG4 diagram. The 2-pole manual transfer switches are quite expensive and BIG. From what I understand, the breaker interlock performs the same function. I have a few questions as well as I'm inventorying parts.

1. Assuming breaker interlock is code compliant for my area, are the breaker interlocks any less or more safe than the manual transfer switch?
2. About the feeder tap and breaker, what is the purpose of that 200 amp feeder tap breaker since there is already one coming from the main panel?
3. The lockable AC disconnect switch - I guess that's the 2-pole fused disconnect. Could I skip that as a separate element and just have 1 panel that has the main AC line in, with 2 200 amp breakers, one for the inverter, and one for the inverter bypass to transfer/interlock? (I've included a diagram here to show what I mean)
4. How important are surge arrestors for the 18Kpv inverter, could I skip those?

As to point 3, this was a local requirement for my incoming service provider. You'd need to check with them and local code to see if it is a requirement in your situation.

 

[solarenvy]

Noted. I can not run Load and Grid to the same panel at the same time without back-feeding the grid in a grid down situation.

If I purchase two EG4 6000XP's and parallel them, I know this would double my output from 6000W to 12000W. Does this also double the grid passthrough from 50amps to 100amps, provided that I wire both Grid's to my incoming service panel and both Load's to a secondary critical loads panel?

Yes, you'll essentially have double the everything. But, you need to make sure you plan for that end-to-end. If you want your loads to have access to 100A of pass-through / bypass grid power, all conductors and breakers must support that throughput. Also the case for the 25A (x2) AC coming from the inverters. Best to combine them using a combiner box.

Here's my dual 6000XP wiring diagram: https://diysolarforum.com/threads/dual-eg4-6000xp-wiring-please-review.78087/

 

[JoshN123]

Yes, you'll essentially have double the everything. But, you need to make sure you plan for that end-to-end. If you want your loads to have access to 100A of pass-through / bypass grid power, all conductors and breakers must support that throughput. Also the case for the 25A (x2) AC coming from the inverters. Best to combine them using a combiner box.

Here's my dual 6000XP wiring diagram: https://diysolarforum.com/threads/dual-eg4-6000xp-wiring-please-review.78087/

Thank you. This is really helpful.

 

[bfaubion]

@JoshN123 I'm trying to make similar decisions as you.. Either an 18Kpv, or 2 of the 6000XP. I don't have a ton to benefit from the 18Kpv energy export, because San Diego has such low compensation on energy exported to them. Additionally, someone mentioned that if I'm using an off-grid inverter, without export capability, then that doesn't require a solar permit. (I'm also doing ground mount under 5 feet, so no building permit). However, I'll at least need the electrical permit for the wiring work. Questions for you

• What do you think the benefit is of 2 6000xp over the 18Kpv?
• What products have you thought about using for the disconnect switch (between the 200 amp main and inverter)?
• What product have you thought about using for the Manual Transfer Switch, between the inverter and house sub-panel? Those 200 amp transfer switches are EXPENSIVE.

For me, I either do the 18K and pass through the entire 200 amp, OR I do the 2 6000 XP, and pass through 100 amps. At the moment, my house sub-panel is 200 amps, coming from the 200 amp exterior main panel, so if I have 2 of the 6000XP, I'm cutting that service down in half to 100 amps into the entire home.

 

[JoshN123]

@JoshN123 I'm trying to make similar decisions as you.. Either an 18Kpv, or 2 of the 6000XP. I don't have a ton to benefit from the 18Kpv energy export, because San Diego has such low compensation on energy exported to them. Additionally, someone mentioned that if I'm using an off-grid inverter, without export capability, then that doesn't require a solar permit. (I'm also doing ground mount under 5 feet, so no building permit). However, I'll at least need the electrical permit for the wiring work. Questions for you

• What do you think the benefit is of 2 6000xp over the 18Kpv?
• What products have you thought about using for the disconnect switch (between the 200 amp main and inverter)?
• What product have you thought about using for the Manual Transfer Switch, between the inverter and house sub-panel? Those 200 amp transfer switches are EXPENSIVE.

For me, I either do the 18K and pass through the entire 200 amp, OR I do the 2 6000 XP, and pass through 100 amps. At the moment, my house sub-panel is 200 amps, coming from the 200 amp exterior main panel, so if I have 2 of the 6000XP, I'm cutting that service down in half to 100 amps into the entire home.

The main benefit would be cost savings - a little over $2000 cheaper on the two 6000xps.

You can use an interlock breaker as a manual transfer switch. $20

https://www.amazon.com/Generator-Interlock-Compatible-Electric-HOMCGK2C/dp/B08ZMYKVFF/ref=sr_1_7?crid=1N0P22BRSM125&dib=eyJ2IjoiMSJ9.BV2i8P-nBGP34XpxkuxSilRUY1_3DpD1Th86eSftXJefzE_X2ELB0eEdopZT3-KtORrXAQqimsaFGOCOc_49iNK7UeN5vbY8kX1b9_l4b5BgY04U-aPwhSDGaLW-tYzaNf-LtVw81ybAMcVSU_6jvgMJP9E4lYLIzoDXQb_gzRgVlvbt3vNWK3lXcBZoFc0ukDABq2trAsQEE8BMPDW53XH1PChdoOZlR67PL2hKzyaaWivjqyAYn7P06nafH22HKAGkFowoc2ghckCaLxBes_jxkus53Rzv0MKFvVkL2eA.P5wmo96gDWwSd1xgDumwEkAmKqwXCDT55qeNd-lr9L4&dib_tag=se&keywords=square+d+interlock+breaker&qid=1709244567&s=industrial&sprefix=square+d+interlock+breake%2Cindustrial%2C142&sr=1-7

I was planning to use this for this disconnect switch as it was required to feedback to the grid. I've decide on the 2 XP's so won't be using it.

Siemens 200 Amp 2-Pole 3-Wire General Duty Fused Outdoor GF224NR - The Home Depot General Duty Safety Switches are intended for applications where reliable performance and continuity of service are needed. But where duty requirements are not severe and usual service conditions prevail. www.homedepot.com

Also, if you want to pass along the full 200 amp service to your new load panel, use a circuit breaker sub feed lug and run the full 200 amps from your main panel to your new load panel. This would be turned off with your interlock breaker and you'd need to turn off the breaker to your inverter in order to turn on full 200 amp grid service.

QO2225SL | CIRCUIT BREAKER SUB-FEED LUG | Square D by Schneider Electric

Square D QO2225SL is available at competitive price! QO2225SL Circuit Breaker Accessory Type at $139.39. Order online!

blackhawksupply.com

 

[bfaubion]

I like the idea of the breaker interlock. I wonder if that breaker interlock panel can facilitate a transfer between the grid (200 amp breaker) and 2 inverter breakers (50 amp each). I updated my diagram here.. am I missing anything? FYI, I plan to work with an electrician on the disconnect and hook up, I just want to make sure I'm understanding how this works so I can use it as a starting point for that person.

 

[Timothyboylan78]

Having issues finding a definite answer. Is it possible to go straight from the meter to the 18kpv and then to the main panel?

 

[DIYrich]

Having issues finding a definite answer. Is it possible to go straight from the meter to the 18kpv and then to the main panel?

Yes. That is the normal path for the power.