EG4 simple critical loads systems

[TessieRed]

Hi, All. This is my first post. Go easy. I'm setting up a simple critical loads system in my house using the Reliance Controls Pro/Tran 2 Manual transfer switch (125 volts, 6 circuits). This transfer switch does not switch neutral but is popular for retrofits because it combines the transfer switch and critical load box.

My current plan is to use the EG4 3000EHV-48 inverter and connect it to a EG4-LL 48V server rack battery. I'll use a NEMA L5-30 cord to connect the AC output of the inverter to the transfer switch inlet. Simple. When grid is down, I can switch to the generator side of the transfer switch and energize my fridge, natural gas furnace, internet, etc.

However, I've been reading about the nonsense going on with EG4 and the Neutral/Ground bonding screw. My main panel is ground/neutral bonded (as it should be). Thus, since the transfer switch does not switch neutral, the inverter must NOT be ground/neutral bonded. However, based on the discussion in this thread, it's not clear if if that is supported by the 3000EHV-48.

How does this community recommend I proceed? I have the reliance transfer switch (model 306a1) already installed. I like the eg4 inverter and battery for its (seeming) safety, performance, and rock bottom price. However, if this nonsense continues, I don't think I want to get into this mess.

I was planning on slapping on a few solar panels in series that met the voltage requirement of the inverter and never charging from grid AC input. However, it would be nice to have the option (safely).

Should I proceed with this purchase before their sale ends? Are there other all-in-one inverters (~$700 like EG4 3k) that this community recommends?

Thanks, everyone. Looking forward to contributing my research and experience to the community.

I had the same thought and not a clear answer like you. The best answer I can give you is you should have neutral and ground bonded in your main panel and in this instance based on your system designed you should do so. Remove the neutral ground bonding screw if present.

I have a similar set up minus the transfer switch as I purchased a EG4 6K Split Phase Inverter. The transfer switch is built in. I recommend installing this inverter instead.

 

[radiocq]

I had the same thought and not a clear answer like you. The best answer I can give you is you should have neutral and ground bonded in your main panel and in this instance based on your system designed you should do so. Remove the neutral ground bonding screw if present.

I have a similar set up minus the transfer switch as I purchased a EG4 6K Split Phase Inverter. The transfer switch is built in. I recommend installing this inverter instead.

Good advice. My main panel is NG bonded (as it should be). I will make sure the inverter is not NG bonded. One NG bond (at the main panel) to rule them all.

How does the EG4 6K execute the transfer? How are loads/circuits chosen to back up? I don't see any mention int he spec sheet about a built in transfer switch.

 

[TessieRed]

Good advice. My main panel is NG bonded (as it should be). I will make sure the inverter is not NG bonded. One NG bond (at the main panel) to rule them all.

How does the EG4 6K execute the transfer? How are loads/circuits chosen to back up? I don't see any mention int he spec sheet about a built in transfer switch.

Good advice. My main panel is NG bonded (as it should be). I will make sure the inverter is not NG bonded. One NG bond (at the main panel) to rule them all.

How does the EG4 6K execute the transfer? How are loads/circuits chosen to back up? I don't see any mention int he spec sheet about a built in transfer switch.

It’s not mentioned specifically, but for example I have AC input from the grid. The inverter can be set pull from the grid when Solar and/or battery cannot sufficiently power the loads. This is the definition of a transfer switch and the capability you are seeking.

Correct me if I am wrong. I am just doing my best to answer your question and possibly simplify you install.

 

[timselectric]

Both of these AIO's have built-in transfer switches.

 

[TessieRed]

It’s not mentioned specifically, but for example I have AC input from the grid. The inverter can be set pull from the grid when Solar and/or battery cannot sufficiently power the loads. This is the definition of a transfer switch and the capability you are seeking.

Correct me if I am wrong. I am just doing my best to answer your question and possibly simplify you install.

The loads and circuits you have in your “Panel” will be the ones powered unless you switch them off via the breaker.

 

[radiocq]

I have been using AC coupling for years to leverage my GT solar to compliment my hybrid inverters. Part of my evolution has been a result of the changing ecoonomics of Net Energy Metering in California. Now I am evolving toware more self consumption of my solar production. Your mileage may be different in Michigan. I also charge two EVs and try to do it from solar because my cost of kWhs produced by my solar is even less than my EV overnight rate. It all depends on where you are standing.

I'd love to talk to you about this. I never considered using my IQ7+ micros. It's a small system. 4.3 kW. It seems the Sol-Ark is how you do it?

I also drive an EV (Leaf, 62 kWh). I just plug in when the Sun is up to maximize solar storage. Wish the Walbox Quasar would come out already!

Here in Michigan I buy for 16 cents per kWh and sell back to the utility for 8 cens per kWh. These numebrs include all taxes and fees. Not the best, not the worst. We're an effcicient family using about 350-400 kWh per month (pre solar). Our low usage makes payback longer.

 

[radiocq]

The loads and circuits you have in your “Panel” will be the ones powered unless you switch them off via the breaker.

I see. Are you backfeeding a breaker in your main panel or a sub panel with the EG4 inverter and using an interlock (for instance)?

 

[timselectric]

Sub panel

 

[Ampster]

I'd love to talk to you about this.

I am happy to talk via PM but others will benefit from this conversation if we keep it open.
Your rate structure favors self consumption as you have figured out with your EVs. I have two EVs and try to charge them during the day when possible.

My last two hybrid inverters were able to prioritize self consumption of solar because i have figured that is the most cost effective. Your rate differentials are small and mine are the same proportions but significantly higher. In Summer my rates are $0.55/kWh for Peak and about $0.25kWh off peak. I have estimated my amortized cost of solar and storage is about $0.25/kWh so it makes sense for me to store as much as I can to use my batteries to peak shave and not purchase power at peak rates. Besides the economics the physics of not using fossil fuel generated electricity makes me feel good and gives me bragging right amongst my liberal friends. I only use the economics argument with my conservative friends.

 

[TessieRed]

I see. Are you backfeeding a breaker in your main panel or a sub panel with the EG4 inverter and using an interlock (for instance)?

Not currently using an interlock. Inverter is set to not backfeed to the home.

 

[Adam De Lay]

Here in Michigan I buy for 16 cents per kWh and sell back to the utility for 8 cens per kWh. These numebrs include all taxes and fees. Not the best, not the worst. We're an effcicient family using about 350-400 kWh per month (pre solar). Our low usage makes payback longer.

It’s funny how many other people I come across from MI that have some kind of solar system. Obviously it’s because we live in such a sunny state with mild winters…. ?

 

[radiocq]

Not currently using an interlock. Inverter is set to not backfeed to the home.

Would you mind describing how it connects to your home loads?

 

[Adam De Lay]

Would you mind describing how it connects to your home loads?

In my case, I have the outputs of my inverters going to a sub panel which is basically my “inverter combiner panel”. From there I have 4awg running to a 60a double pole breaker in one of my house sub panels. That house sub panel has an interlock kit which lets me only choose between grid or solar at one time.

At some point I want to look at a manual transfer switch, but there’s a lot of variables in my case (a couple being available space and distance between sub panels).

 

[John Frum]

In my case, I have the outputs of my inverters going to a sub panel which is basically my “inverter combiner panel”. From there I have 4awg running to a 60a double pole breaker in one of my house sub panels. That house sub panel has an interlock kit which lets me only choose between grid or solar at one time.

At some point I want to look at a manual transfer switch, but there’s a lot of variables in my case (a couple being available space and distance between sub panels).

Where is the neutral/ground bond?

 

[radiocq]

I think I've decided to go with the EG4 3k based on what you all have shared despite the lack of clarity from Signature Solar (on common neutral and NG bonding). The essence of the question is... is it safe to use a common neutral transfer switch like reliance controls type switches with an inverter like the EG4 3k.

It seems like the answer is yes. Safe so long as the NG bonding screw is removed from the inverter and there is a NG bond in the main panel.

Then, you must never plug in the inverter AC input to grid while the inverter is connected to the transfer switch. Want to charge your battery from the AC input? You must disconnect from the transfer switch to do it safely. In this case the NG bond happens at the AC input connection going to the main panel so you still have just a single NG bond.

Are all my assumptions reasonable and correct?

 

[Adam De Lay]

Where is the neutral/ground bond?

The bond is in my main service panel.

 

[TessieRed]

Would you mind describing how it connects to your home loads?

Sure.

I have wire running from a 50A Breaker in my home MSP directly to a “AC Input” terminal
Block located within the inverter.

The inverter has the capability to backfeed to the grid if I so chose in the settings.

To be clear I have not attempt to power any home loads this way. I have not be permitted to do so.

 

[TessieRed]

I think I've decided to go with the EG4 3k based on what you all have shared despite the lack of clarity from Signature Solar (on common neutral and NG bonding). The essence of the question is... is it safe to use a common neutral transfer switch like reliance controls type switches with an inverter like the EG4 3k.

It seems like the answer is yes. Safe so long as the NG bonding screw is removed from the inverter and there is a NG bond in the main panel.

Then, you must never plug in the inverter AC input to grid while the inverter is connected to the transfer switch. Want to charge your battery from the AC input? You must disconnect from the transfer switch to do it safely. In this case the NG bond happens at the AC input connection going to the main panel so you still have just a single NG bond.

Are all my assumptions reasonable and correct?

I think you should check out my other posts about my Tesla Charger. There’s a guy in the comments who is probably the most knowledgeable on the NG bond situation.

Tbh, there are just to many people saying different things. Will Prowse says it shouldn’t be bonded, but that was before they said they were not going to ship the new ones with the bonding screw?

All I can tell you is I bought my inverter within the past three months and I have had no NG bonding issues while also utilizing AC Input.

actually if I want to charge from the Grid I set my priority. For example once Solar and the battery and depleted the grid will come into play to help power the loads. I don’t have to go do anything.

As an apprentice electrician, I’m going go with the tried and true method of one NG bond in the MSP.

 

[radiocq]

I think you should check out my other posts about my Tesla Charger. There’s a guy in the comments who is probably the most knowledgeable on the NG bond situation.

I'll check it out.

Tbh, there are just to many people saying different things. Will Prowse says it shouldn’t be bonded, but that was before they said they were not going to ship the new ones with the bonding screw?

Honestly, I think everyone is saying the same thing. Just make sure there is one neutral-ground bond. Interacting with the grid in some way? Make sure the NG bond happens in the main panel and nowhere else. Operating mobile? Then the NG bond can happen at the inverter.

All I can tell you is I bought my inverter within the past three months and I have had no NG bonding issues while also utilizing AC Input.

actually if I want to charge from the Grid I set my priority. For example once Solar and the battery and depleted the grid will come into play to help power the loads. I don’t have to go do anything.

As an apprentice electrician, I’m going go with the tried and true method of one NG bond in the MSP.

This is surprising, but it may just be because I'm new to the off-grid world. I'm a physicist and teach intro college electromagnetism amongst other things. I have little practical experience with off-grid and grid-tie systems, however.

From what you've posted you have a NG bond at the main service panel (good). You also have AC input connected to grid. This will result in ground and neutral loop, as @timselectric said.

 

[TessieRed]

I'll check it out.

Honestly, I think everyone is saying the same thing. Just make sure there is one neutral-ground bond. Interacting with the grid in some way? Make sure the NG bond happens in the main panel and nowhere else. Operating mobile? Then the NG bond can happen at the inverter.

This is surprising, but it may just be because I'm new to the off-grid world. I'm a physicist and teach intro college electromagnetism amongst other things. I have little practical experience with off-grid and grid-tie systems, however.

From what you've posted you have a NG bond at the main service panel (good). You also have AC input connected to grid. This will result in ground and neutral loop, as @timselectric said.

I actually thought the same thing, but the system functions perfectly.

From my research, a ground and neutral loop for this system will only occur if my Off-Grid panel was wired as a sub panel from my MSP.

The off grid panel has its own ground rod and the Home MSP has its own