Complete guide for 48V using EG4 18k

[y0bailey]

Depending on the needs of the system, the EG4 18Kpv can be a reasonably straightforward install

View attachment 161412

The above diagram assumes you are doing a whole-house backup and works for up to a 200A utility feed. The inverter goes between the utility meter and the existing breaker box. The inverter will 'only' produce a continuous 50A @ 240V (12KW) but the run surge capabilities can deal with surges greater than 12KW. For many households, it will carry the load, but if the 'normal' load is higher than 12K the user may need to cut back on some higher-wattage appliances when the power is down.

The AC disconnect may need to be added if there is not one at the meter. The disconnect should be rated for the current rating of your service.
If the service into the home is the full 200A the lines between the meter and the breaker need to be at least 3/0 AWG. However, if the service is 100A the lines can be as 'small' as 2 AWG.

There are a lot of options for the batteries, the EG4 LiFePower batteries can work but I prefer the EG4 LL batteries. There are several other brands that work with the inverter. However, if your state requires the combined Inverter/battery UL listing you may need to stick with the EG4 batteries.

The inverter can pull up to 250A from the batteries and most of the server rack batteries have 100A BMSs so the system needs a minimum of 3 100A server rack batteries. This gives 15.36KWh of storage. Depending on the usage pattern and how long you want to be able to run on batteries alone, you may need more batteries. 6 batteries in a server rack is a common set-up for the 18K pv but some folks have more. From your description, there could be a lot of Air Conditioning so make sure to calculate your need and size the battery bank accordingly.

For the PV disconnect, the IMO line seems to work pretty well. If you have 4 strings coming in you will need two 2-string switches.

The availability of any particular panel is so short-lived that recommending a specific panel is a fool's errand. You will need to shop around for what works best for you. I like some of the newer 400+ W panels that are out and the 600V pv-in limit of the 18Kpv can handle reasonably long strings with the higher Voc these panels come with.

If your installation is going to have to meet the code you will need to add Rapid Shutdown receiver Modules to the panels. Tigo has a good line of these.


Note: If you have not done it yet, you should spend some time calculating your peak demand wattage and daily KWh usage. This will inform your decision on the size of your battery bank and the size of your solar array. Your current electric bill will often give you most of this data. You can also use one of the whole-house energy monitors that will plot your usage. If you are building from scratch and don't yet have a history to guide you, an energy audit can be very useful:

System Energy Audit and Sizing Spread Sheet

To get the spreadsheet, click on the orange button at the top of this page. This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess;) Notes...

diysolarforum.com

Finally.... Not shown in the diagram above is a class T fuse between the batteries and the inverter. Some say the battery breakers and BMS over-current is sufficient. However, I like to have a class T fuse between the batteries and the inverter. If you have two server rack batteries, I like to put a fuse after each server rack and then run a cable directly to one of the two battery lugs on the inverter.

Can you help me clarify the ground wire(s) coming from the panel strings?

I always thought this grounding was for lightening strikes, so I was planning on running my panel string ground wire(s) into the grounding rods installed for my home to keep it OUT of the inverter.

Am I overthinking this because it would be a hell of a lot easier to take the ground from the strings into the inverter in my situation.

 

[FilterGuy]

Can you help me clarify the ground wire(s) coming from the panel strings?

I always thought this grounding was for lightening strikes, so I was planning on running my panel string ground wire(s) into the grounding rods installed for my home to keep it OUT of the inverter.

Am I overthinking this because it would be a hell of a lot easier to take the ground from the strings into the inverter in my situation.

A few points.

1) There is no grounding system that can properly protect from a direct lightning strike. That requires a separate lightning protection system. However, when properly grounded, a system will have some degree of protection from a nearby lightning strike.

2) The PV PE terminals on the 18Kpv can be used for the frame and mount grounding of the array, but it is not required. The NEC typically requires the Equipment Grounding Conductor (EGC) to be routed with the associated power conductors, but there is a specific exception for the PV grounding. I don't know why they put the carv out in the code, but I suspect it is because the PV EGC is more exposed to issues with nearby strikes.

Your plan of taking the PV EGC directly to grounding for the house is both allowed and IMO, a good idea.

 

[FilterGuy]

@FilterGuy On July 29th I do see 136.3kWh, here is a screenshot directly from utility company. The summer hasn't been too kind to the Phoenix Arizona area. Paying $600/mo utility bills is a big driver in my offgrid solar efforts.

View attachment 162896

Wow!! That is a lot of power. Whether the proposed system is big enough for you is very dependent on what you want out of it.

Without a lot more information, it is hard to say what your system needs are, but it seems likely that the 12KW of the 18Kpv will not cover your peak loads and will require assistance from the grid. That means that in a grid-down situation, you will probably have to avoid the use of some of the high-wattage loads. The inverter will probably not be able to power them all at once.

The storage of two of the wall mount batteries would come to 28.6KWh. That is only 21% of the daily usage. This could be used to do peak shaving, but in a grid-down scenario, the usage in the house would have to be drastically cut or the batteries would be empty in just a few hours.

 

[Jdcarrol]

Wow!! That is a lot of power. Whether the proposed system is big enough for you is very dependent on what you want out of it.

Without a lot more information, it is hard to say what your system needs are, but it seems likely that the 12KW of the 18Kpv will not cover your peak loads and will require assistance from the grid. That means that in a grid-down situation, you will probably have to avoid the use of some of the high-wattage loads. The inverter will probably not be able to power them all at once.

The storage of two of the wall mount batteries would come to 28.6KWh. That is only 21% of the daily usage. This could be used to do peak shaving, but in a grid-down scenario, the usage in the house would have to be drastically cut or the batteries would be empty in just a few hours.

@FilterGuy , I am looking at improving energy efficiency as well as produce our own energy. For example, the house was built in 1960 and most windows are single pane.

My thought I'm trying to work towards is to have the system use solar panels to power the house + charge enough battery capacity to power the house during the night which has much lower usage. Do you feel that would be a fools errand?

 

[y0bailey]

A few points.

1) There is no grounding system that can properly protect from a direct lightning strike. That requires a separate lightning protection system. However, when properly grounded, a system will have some degree of protection from a nearby lightning strike.

2) The PV PE terminals on the 18Kpv can be used for the frame and mount grounding of the array, but it is not required. The NEC typically requires the Equipment Grounding Conductor (EGC) to be routed with the associated power conductors, but there is a specific exception for the PV grounding. I don't know why they put the carv out in the code, but I suspect it is because the PV EGC is more exposed to issues with nearby strikes.

Your plan of taking the PV EGC directly to grounding for the house is both allowed and IMO, a good idea.

Thanks for clarifying.

A few additional questions/thoughts.

I have two PV arrays, one on the roof, one ground mount. The ground mount does have a grounding rod there, it ties into the 6 AWG wire that runs with the string. I will be joining the grounds of both array strings, and then dumping that into the grounding rod for the main house.

It will save me some complexity to just use the PV PE terminals on the 18kpv, but would that be dumb? It is still at least tied into the ground mounted panels grounding rod there.

Basically, sell me on tying things into the main house ground rod vs. being lazy and using the inverter?!

 

[42OhmsPA]

@FilterGuy , I am looking at improving energy efficiency as well as produce our own energy. For example, the house was built in 1960 and most windows are single pane.

My thought I'm trying to work towards is to have the system use solar panels to power the house + charge enough battery capacity to power the house during the night which has much lower usage. Do you feel that would be a fools errand?

View attachment 162901

What is your current HVAC setup?
That is a large amount of power to offset with solar, I think you'd be much better starting with increasing efficiencies of HVAC, appliances, led bulbs, etc.
5kwh /hr overnight is huge... My house idles under 500w including my cheap inverters 135+w consumption...

Can you provide a more detailed list of your loads?

 

[Jdcarrol]

What is your current HVAC setup?
That is a large amount of power to offset with solar, I think you'd be much better starting with increasing efficiencies of HVAC, appliances, led bulbs, etc.
5kwh /hr overnight is huge... My house idles under 500w including my cheap inverters 135+w consumption...

Can you provide a more detailed list of your loads?

@420hmsPA, We have two systems, 1 is a 5 ton HVAC system another is a 3 ton HVAC system. Do you live somewhere warm? hah, I know there is a lot. trying to tackle it from both ends, reduce consumption and produce my own.

 

[FilterGuy]

I am looking at improving energy efficiency as well as produce our own energy.

Good call. A lot of times, reducing the load is a far better option than trying to power all the inefficiencies. Not only that, I think you will find that better windows and better insulation will make the house quieter and a lot more comfortable. When we did that, the temperature was a lot more consistent throughout the house.

My thought I'm trying to work towards is to have the system use solar panels to power the house + charge enough battery capacity to power the house during the night which has much lower usage. Do you feel that would be a fools errand?

No. Not a fools errand at all. Just be sure to run the numbers so you understand what the system will/will not do.

 

[FilterGuy]

Thanks for clarifying.

A few additional questions/thoughts.

I have two PV arrays, one on the roof, one ground mount. The ground mount does have a grounding rod there, it ties into the 6 AWG wire that runs with the string. I will be joining the grounds of both array strings, and then dumping that into the grounding rod for the main house.

It will save me some complexity to just use the PV PE terminals on the 18kpv, but would that be dumb? It is still at least tied into the ground mounted panels grounding rod there.

Basically, sell me on tying things into the main house ground rod vs. being lazy and using the inverter?!

Several points

• The PV grounding is required to tie back into the same grounding system of the house.
• The grounding rod at the ground mount is allowed, but it is not required. I would remove it. (The extra ground rod can actually make problems from a nearby lightning strike worse)
• On the 18Kpv the 'PE' or ground bus for the PV is tied directly to the PE/Ground bus for the AC. Consequently, if the system is set up properly, if you run the PV ground to the PV PE/Ground of the inverter, it will also be tied to the home AC grounding system and should meet the code.
• IMO, running the PV ground directly to the home ground at the box where the home's grounding rods are tied in is better than tieing it in through the inverter. However, I can not quantify 'better' in any meaningful way. If you are in a place that gets a lot of nearby strikes, you should at least consider running directly to the home's grounding point. If you are in a place where lightning is rare and nearby strikes rarer, maybe go with whatever is easiest.
• If you decide to leave the ground rod at the ground-mount array, you should really consider taking the ground wire to the homes grounding system and not through the inverter (or other equipment)
  
  
• I notice that in newer versions of the code, there are requirements for whole-house surge protectors. I am not sure if surge protectors on the PV are required yet, but you can bet that requirement is coming. A pv surge protector and an AC surge protector near the inverter might be a good idea if you run the PV ground through the inverter. If you live in a lightning-prone area, these protectors are a good idea regardless of how the ground is wired.

 

[y0bailey]

Several points

• The PV grounding is required to tie back into the same grounding system of the house.
• The grounding rod at the ground mount is allowed, but it is not required. I would remove it. (The extra ground rod can actually make problems from a nearby lightning strike worse)
• On the 18Kpv the 'PE' or ground bus for the PV is tied directly to the PE/Ground bus for the AC. Consequently, if the system is set up properly, if you run the PV ground to the PV PE/Ground of the inverter, it will also be tied to the home AC grounding system and should meet the code.
• IMO, running the PV ground directly to the home ground at the box where the home's grounding rods are tied in is better than tieing it in through the inverter. However, I can not quantify 'better' in any meaningful way. If you are in a place that gets a lot of nearby strikes, you should at least consider running directly to the home's grounding point. If you are in a place where lightning is rare and nearby strikes rarer, maybe go with whatever is easiest.
• If you decide to leave the ground rod at the ground-mount array, you should really consider taking the ground wire to the homes grounding system and not through the inverter (or other equipment)
  
  
• I notice that in newer versions of the code, there are requirements for whole-house surge protectors. I am not sure if surge protectors on the PV are required yet, but you can bet that requirement is coming. A pv surge protector and an AC surge protector near the inverter might be a good idea if you run the PV ground through the inverter. If you live in a lightning-prone area, these protectors are a good idea regardless of how the ground is wired.

Lovely answer, thanks.

I'll just do the extra work and get it to the main ground rod to be safest.

 

[42OhmsPA]

@420hmsPA, We have two systems, 1 is a 5 ton HVAC system another is a 3 ton HVAC system. Do you live somewhere warm? hah, I know there is a lot. trying to tackle it from both ends, reduce consumption and produce my own.

I'd definitely look into updating the hvac, especially if they are older units.
I installed a 1 Ton mini split in April, my 3 ton 10yr old hasn't turned on once this summer. It's currently 85F outside, 69 inside the 850sf I'm conditioning with the mini split.
I live in PA, we can have single to triple digits.

You'll find @FilterGuy to be incredibly helpful and knowledgeable. Many of his posts were invaluable to me when I started this addiction.

 

[EastTexCowboy]

Before I answer that, can you confirm the house is using as much as 145KWh in one day? That is a huge amount for one house.

Meanwhile, the EG4 18Kpv is a 12KW inverter. That means it can draw 12000W/51.2V=234A continuously. The EG4 Wall Mount battery can only provide 200A continuously. Consequently, there really should be 2 of the wall mount batteries.

145kwh in a day is not so huge from my experience. He's in Phoenix area so as bad or worse than here in Texas. Before I upgraded my heat pumps I was hitting that much last year on hot days. Really cold winter days were much worse. We had a day last winter with 12F low and something like 22F high - I burned through 270kwh that day but the old heat pumps were VERY inefficient at heating. We'll see how the new ones do this winter. With the 105F to 107F temps we've had the last few weeks I've been hitting around 110 to 115 kwh per day, with 80kwh of that coming from solar. That's with adding a mini-split for the garage and two more freezers than last year, which tells me these mini-splits are really helping.

With a family and four kids I'm going to hazard a guess that @Jdcarrol has a decent size house so I'm not surprised at the usage. Older house even more so.

 

[EastTexCowboy]

Wow!! That is a lot of power. Whether the proposed system is big enough for you is very dependent on what you want out of it.

Without a lot more information, it is hard to say what your system needs are, but it seems likely that the 12KW of the 18Kpv will not cover your peak loads and will require assistance from the grid. That means that in a grid-down situation, you will probably have to avoid the use of some of the high-wattage loads. The inverter will probably not be able to power them all at once.

The storage of two of the wall mount batteries would come to 28.6KWh. That is only 21% of the daily usage. This could be used to do peak shaving, but in a grid-down scenario, the usage in the house would have to be drastically cut or the batteries would be empty in just a few hours.

I agree, with emphasis on if the grid is down he's going to need to manage power very carefully - especially the battery capacity. That said, it's partly about expectations. For us, the grid going down is certainly always a possibility but we have a whole house NG generator. We also have 60kwh or batteries with plans to add at least another rack of 30kwh and maybe two of them. And we still realize that if the grid is down for more than a day or two we can expect to have to manage our power use.

@Jdcarrol , if you're planning on having AC in a grid down situation I'd recommend some kind of generator to supplement the batteries. And double your battery capacity at least. Double won't be enough but a generator might make more sense than more batteries at some point.

 

[FilterGuy]

That said, it's partly about expectations.

That is why I said:

Just be sure to run the numbers so you understand what the system will/will not do.

 

[y0bailey]

Several points

• The PV grounding is required to tie back into the same grounding system of the house.
• The grounding rod at the ground mount is allowed, but it is not required. I would remove it. (The extra ground rod can actually make problems from a nearby lightning strike worse)
• On the 18Kpv the 'PE' or ground bus for the PV is tied directly to the PE/Ground bus for the AC. Consequently, if the system is set up properly, if you run the PV ground to the PV PE/Ground of the inverter, it will also be tied to the home AC grounding system and should meet the code.
• IMO, running the PV ground directly to the home ground at the box where the home's grounding rods are tied in is better than tieing it in through the inverter. However, I can not quantify 'better' in any meaningful way. If you are in a place that gets a lot of nearby strikes, you should at least consider running directly to the home's grounding point. If you are in a place where lightning is rare and nearby strikes rarer, maybe go with whatever is easiest.
• If you decide to leave the ground rod at the ground-mount array, you should really consider taking the ground wire to the homes grounding system and not through the inverter (or other equipment)
  
  
• I notice that in newer versions of the code, there are requirements for whole-house surge protectors. I am not sure if surge protectors on the PV are required yet, but you can bet that requirement is coming. A pv surge protector and an AC surge protector near the inverter might be a good idea if you run the PV ground through the inverter. If you live in a lightning-prone area, these protectors are a good idea regardless of how the ground is wired.

Alright, I read this a few more times and now I've changed my plan. Let me know if it sounds crazy.

MORE INFO:
My house and panels are LOW. (Winter shading is terrible - thanks original scam artists that sold me my system and went bankrupt!!). No less than 50 trees at a higher elevation than my roof mount panels, and the worlds largest tree south of my ground mount panels. I don't think I'm getting a direct hit by lightening anytime soon. I'm just getting this lightening "act of god" bullshit out of my brain.

Picture for fun...does that look a lightening rod to anyone? (sarcasm)



I'm going to disconnect the ground rod from the ground mount panels...you are right, they are by a huge tree. It's going to get hit first and then may travel into my ground rod there.

I'm going to ignore my misunderstanding on "grounding is for lightening" and just plan for "will this pass code while keeping the install as simple as my brain can handle." My lightening risk is low.

So, now the plan is to disconnect the ground rod from the ground mount array, run the ground wires with the PV strings to the inverter (one conduit run instead of two....Original plan being one conduit run of the strings to the inverter in the basement and another 15 foot conduit run with the ground to the mains ground rod on the exterior of the house).

Thoughts?



I cannot express to you how much I appreciate your responses. I don't know if you work for EG4 or not, but if you do and anyone is watching, your responses and diagrams have given me the confidence to click buy yesterday. EG4-18Kpv + the new PowerPro ordered.

Seriously...thank you, and the company should thank you.

 

[FilterGuy]

Alright, I read this a few more times and now I've changed my plan. Let me know if it sounds crazy.

MORE INFO:
My house and panels are LOW. (Winter shading is terrible - thanks original scam artists that sold me my system and went bankrupt!!). No less than 50 trees at a higher elevation than my roof mount panels, and the worlds largest tree south of my ground mount panels. I don't think I'm getting a direct hit by lightening anytime soon. I'm just getting this lightening "act of god" bullshit out of my brain.

Picture for fun...does that look a lightening rod to anyone? (sarcasm)
View attachment 162947


I'm going to disconnect the ground rod from the ground mount panels...you are right, they are by a huge tree. It's going to get hit first and then may travel into my ground rod there.

I'm going to ignore my misunderstanding on "grounding is for lightening" and just plan for "will this pass code while keeping the install as simple as my brain can handle." My lightening risk is low.

So, now the plan is to disconnect the ground rod from the ground mount array, run the ground wires with the PV strings to the inverter (one conduit run instead of two....Original plan being one conduit run of the strings to the inverter in the basement and another 15 foot conduit run with the ground to the mains ground rod on the exterior of the house).

Thoughts?



I cannot express to you how much I appreciate your responses. I don't know if you work for EG4 or not, but if you do and anyone is watching, your responses and diagrams have given me the confidence to click buy yesterday. EG4-18Kpv + the new PowerPro ordered.

Seriously...thank you, and the company should thank you.

That sounds fine.

 

[EastTexCowboy]

Alright, I read this a few more times and now I've changed my plan. Let me know if it sounds crazy.

MORE INFO:
My house and panels are LOW. (Winter shading is terrible - thanks original scam artists that sold me my system and went bankrupt!!). No less than 50 trees at a higher elevation than my roof mount panels, and the worlds largest tree south of my ground mount panels. I don't think I'm getting a direct hit by lightening anytime soon. I'm just getting this lightening "act of god" bullshit out of my brain.

Picture for fun...does that look a lightening rod to anyone? (sarcasm)
View attachment 162947


I'm going to disconnect the ground rod from the ground mount panels...you are right, they are by a huge tree. It's going to get hit first and then may travel into my ground rod there.

I'm going to ignore my misunderstanding on "grounding is for lightening" and just plan for "will this pass code while keeping the install as simple as my brain can handle." My lightening risk is low.

So, now the plan is to disconnect the ground rod from the ground mount array, run the ground wires with the PV strings to the inverter (one conduit run instead of two....Original plan being one conduit run of the strings to the inverter in the basement and another 15 foot conduit run with the ground to the mains ground rod on the exterior of the house).

Thoughts?



I cannot express to you how much I appreciate your responses. I don't know if you work for EG4 or not, but if you do and anyone is watching, your responses and diagrams have given me the confidence to click buy yesterday. EG4-18Kpv + the new PowerPro ordered.

Seriously...thank you, and the company should thank you.

@FilterGuy was actually just as generous with his time before he started consulting for SS. Helped me get past a number of hurdles. He and a few others here. But I'm thinking James should still give him a bonus ...

 

[G00SE]

@420hmsPA, We have two systems, 1 is a 5 ton HVAC system another is a 3 ton HVAC system. Do you live somewhere warm? hah, I know there is a lot. trying to tackle it from both ends, reduce consumption and produce my own.

I used to live in Phoenix. I upgraded my 15yr old heat pump to a new trane two stage, got the ducts redone, and had my attic insulated and I dropped my monthly utility bill 150/mo in summer
The house after that we had a 2 story with two units and our summer average was <50kwh in a day.
I’d definitely explore the window upgrade and other cost saving measures
One things for sure, I don’t miss the heat! Now I just typically yearn for oxygen instead hah

 

[Skypower]

This is an offgrid design I recently helped someone do:

View attachment 161427

I like the buck converter for the gateway?

 

[FilterGuy]

I like the buck converter for the gateway?

Yup.... it allows access even if the system is down. We talked about getting the cell modem that plugs directly into the inverter, but the owner wanted to have wifi for other things if he was going to be paying for a cell service.