New SRNE 30kw+ parallel build

[Zwy]

You have to remember when a large inductive load kicks off, there is some flyback plus if batteries are full, there is not an immediate shut down of the AC coupling. This energy has to go somewhere, it doesn't bother if the batteries aren't full as that energy will be put into the batteries on for example, a Victron Quattro system with AC coupling on the inverter output. AC coupled on the output allows for easy battery charging on the Victron Quattro if desired. With some inverters, that power will be pushed back on to grid. Using a hybrid inverter with AC coupling on the output but no grid connection could cause some problems if the battery bank is at full SOC but users have reported the small amount of power until the AC coupled grid tie array is toggled off is not enough to cause an issue.

The ASP's have a function where PV power is used primary and supplemented by grid. Another is grid is used as primary and PV/battery power is secondary. Grid tie would be used on the AC input, thus PV power from the MPPT's would be used first to power loads, then supplemented with grid. The HEBP allows blending of power also similar to this function, it can be from PV as primary, grid or AC coupled as secondary. Using the generator port on the HEBP with the generator setting set to Micro inverter input would allow AC coupling and this power can be sent for loads first, battery charging first or to grid first. The combination of settings will allow for desired operation. You will have to study the manual in depth to decide how you want to have the inverter function.

SRNE always shows this diagram for AC coupling.

I would recommend contacting SRNE support for the correct wiring and settings before installing the HEBP. I have used this form in the past and response was within 24 hours due to the time difference. I was impressed by how fast tech support responded.

 

[davewsail]

As I'm waiting for my HEBPs (supposedly shipped today), I'm continuing to monitor my current setup. Today was a hot day and I'm seeing that I that I'm pulling up to 65 amps on one phase and about 55 amps on the other when ACs are on, my wife is washing clothes, Tesla is charging, etc... My peak load will probably be in the evening when it is still warm and we are doing all the other stuff. So the inverters will be pulling from battery or the grid depending on how I set things. If battery (a definite on an outage), that would be ~300A discharge to the parallel HEBPs. The manual says to use 2/0 cable and has 2 terminals per inverter so that would be 6 2/0 cables splitting 300A-- more than enough. My battery config is 2 parallel stacks of 4 packs. Within a stack, each battery pack connects directly to a bus bar. I'm freaking out about the connections coming off each stack (seen some of the warning threads about DC current on here).

I can put in external bus bars but each stack has to send power through a cable to the bus bar. I'm worried that will be the weak/potential breaking point for my system. Part of my freaking out is I'm really new to this and unsure what adequate safety precautions are (actually way more than adequate because I don't push limits). I certainly don't want to be posting later about how my house burned down. I'm way less comfortable on the DC side of things than the AC side and local electricians have no idea either. Appreciate any pointers/thoughts you all have for me on this.

PS, Are the unbalanced phases an issue for inverters? Doesn't seem too bad but again, no experience here.

 

[Zwy]

I run 4/0 to the Lynx busbar, then split off to each inverter using 2/0 with a Class T for each inverter. It is not just amperage but also voltage drop.

Not sure if you saw my build thread and videos but might give you some ideas.

Imbalance between phases has not been a problem. In my build thread, there is a second load testing video where I shut off one inverter and basically maxed out one phase and no inverter shutdown or other issues. Imbalance was a minimum of 3Kw as the work trailer was only wired for 120V.

 

[davewsail]

I run 4/0 to the Lynx busbar, then split off to each inverter using 2/0 with a Class T for each inverter. It is not just amperage but also voltage drop.

Not sure if you saw my build thread and videos but might give you some ideas.

Imbalance between phases has not been a problem. In my build thread, there is a second load testing video where I shut off one inverter and basically maxed out one phase and no inverter shutdown or other issues. Imbalance was a minimum of 3Kw as the work trailer was only wired for 120V.

Thank you, this is helpful. I watched your video before but needed to go back to it. I see you put class T fuses on the lines to inverters. Inside your cabinet I think you also have class T fuses between modules? As I will have 2 parallel stacks, should I put class T fuses between each stack and the lynx?

 

[davewsail]

Curious on thoughts of using LittelFuse instead of class T for integration in the Lynx? It would keep my install cleaner and more compact. But I see most folks here use Class T. I'm just curious on why.

 

[Zwy]

Thank you, this is helpful. I watched your video before but needed to go back to it. I see you put class T fuses on the lines to inverters. Inside your cabinet I think you also have class T fuses between modules? As I will have 2 parallel stacks, should I put class T fuses between each stack and the lynx?

I have a Class T to each inverter and a Class T on every battery pack. I always have a Class T on each battery, my house bank is the same.
@upnorthandpersonal explained why very well here.

Post in thread '5th day of no sun'

Nov 25, 2024

Do we have any tests that show a class T fuse will stop the kind of amperage it might get hit with on a bank that size?

A class T fuse has a breaking capability of 20kA.

If we assume an internal resistance of 0.2 mR in a typical 280Ah cell, and a configuration at 16s, we get a 51.2V nominal voltage with an internal resistance of 16 x 0.2 mR = 3.2mR (this ignores all the bus bar resistance, which is not negligible to be honest). This means we could see a short circuit current of 16kA.

This is most definitely a theoretical maximum and this can not be sustained. For one, the...

• upnorthandpersonal

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[Zwy]

Curious on thoughts of using LittelFuse instead of class T for integration in the Lynx? It would keep my install cleaner and more compact. But I see most folks here use Class T. I'm just curious on why.

Breaking capability is the reason I use the Class T fuses. That and the arc is contained inside the fuse, no chance of arcing outside the Class T.

Have you read the house burned down thread?

J

Thread 'House burned down'

Apr 28, 2024

So, after 4 to 5 years of working flawless, the 100 kwh lifepo4 battery caught fire at night and burned our house down. Luckily our family just made in out on time.
Inspection of the fire expert revealed that a melt fuse melted, and created an arc between the 2 points wich ultimatly started the fire.
So i learned to not use melt fuse anymore, plus once the house is rebuild, i will put the new system in a seperate shed outdoor.

• Jejochen
• Replies: 1,152
• Forum: Up in smoke... learn from my mistake!

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[davewsail]

Have you read the house burned down thread?

That's all I need to know. It is worth whatever it takes to prevent a catastrophe. My house is made of cinder block and rebar so wouldn't actually burn down but it could destroy my pump/electrical room which would make the house unlivable for probably quite a while. Curious if you use individual class T holders or something like the Victron class T distributor. To protect each inverter and each battery connection, I'll need 8 fuses: 3 inverters x 2 battery connections each + 2 battery stacks.

 

[agtcovert]

That's all I need to know. It is worth whatever it takes to prevent a catastrophe. My house is made of cinder block and rebar so wouldn't actually burn down but it could destroy my pump/electrical room which would make the house unlivable for probably quite a while. Curious if you use individual class T holders or something like the Victron class T distributor. To protect each inverter and each battery connection, I'll need 8 fuses: 3 inverters x 2 battery connections each + 2 battery stacks.

I can tell you what I did - and what I would do differently.

Each of my battery packs goes to a Victron T-class power in. I join the T-class power in to a lynx distributor, negative with a 1000A smartshunt, the positive is connected with a single pole Dihool MCCB 400A breaker. I made small busbar to bridge these where needed.

This way, each inverter connects to the distributor and has a megafuse protecting it. My chargeverters also land on the distributor and have megafuses as well. The battery side of the bus can be isolated, and any fault originating from any battery has to route through either another fuse or the MCCB. I've tested the MCCB and know it will open with high current.

The only thing I don't like about the t-class power in is the distance from the batteries. If I was doing it over, I'd mount the t-class right by the battery with a Blue Sea t-class fuse holder and run to a regular bus bar or regular Victron power in. The rest would stay the same. Or rig up a way to keep the distance from the power-in to battery at a minimum.

Hopefully that makes some sense. Been up since before 6am and I'm exhausted, working on my RV solar project all day.

 

[Zwy]

Curious if you use individual class T holders or something like the Victron class T distributor. To protect each inverter and each battery connection, I'll need 8 fuses: 3 inverters x 2 battery connections each + 2 battery stacks.

I use individual Class T fuses right at the battery with the holders. I purchase exclusively from Don Rowe.
Best price I have found on Class T fuse and holders.

 

[NC_hydro]

I use individual Class T fuses right at the battery with the holders. I purchase exclusively from Don Rowe.
Best price I have found on Class T fuse and holders.

He's a bit pricey for the fuses, $69 for a 250amp class T. Amazon has blue sea 250amp class T for $45

 

[Zwy]

He's a bit pricey for the fuses, $69 for a 250amp class T. Amazon has blue sea 250amp class T for $45

I just buy the complete holder and fuse. I never blow any fuses but can always rob one out of another fuse and holder.

 

[davewsail]

He's a bit pricey for the fuses, $69 for a 250amp class T. Amazon has blue sea 250amp class T for $45

For once I'm lucky on prices here on Amazon Mexico. I picked up 4 blue sea class T 400 amp for $26/each.

 

[davewsail]

I can tell you what I did - and what I would do differently.

Each of my battery packs goes to a Victron T-class power in. I join the T-class power in to a lynx distributor, negative with a 1000A smartshunt, the positive is connected with a single pole Dihool MCCB 400A breaker. I made small busbar to bridge these where needed.

This way, each inverter connects to the distributor and has a megafuse protecting it. My chargeverters also land on the distributor and have megafuses as well. The battery side of the bus can be isolated, and any fault originating from any battery has to route through either another fuse or the MCCB. I've tested the MCCB and know it will open with high current.

The only thing I don't like about the t-class power in is the distance from the batteries. If I was doing it over, I'd mount the t-class right by the battery with a Blue Sea t-class fuse holder and run to a regular bus bar or regular Victron power in. The rest would stay the same. Or rig up a way to keep the distance from the power-in to battery at a minimum.

Hopefully that makes some sense. Been up since before 6am and I'm exhausted, working on my RV solar project all day.

Thank you for this. very helpful. So ideally I will wire things up as you suggest. The HEBP inverter has an internal DC breaker, so I'm thinking I don't need an external one? So I'd have 400A class T fuses right on the battery terminals. From there run up to a lynx distributor and megafuses to each of the inverters. Each HEBP has 2 battery terminals so 2 connections to the busbar each. Each inverter battery terminal can go up to 120A but if it did, that would be a problem. Anyway if I use 125A megafuses for each inverter DC connection, that's up to 750A total to the busbar to blow the megafuses. The class Ts on the battery would blow at 800A (2 in parallel). Whether 750A or 800A, it seems a bit close, definitely much less 20% higher that rated hybrid charging current. However, my PV system is 29.7kW which at peak would be 619A @48v assuming no load (which there would be). I believe I can program max charging current so think this would work?

I want to see if my logic is correct... The class Ts protect if something bad happens in the battery. The megafuses protect each inverter individually. From my limited understanding reading safety posts on this forum, seems the battery is the high risk location. I know @Zwy uses class T everywhere. I'm open to that -- it just complicates things for me.

 

[Zwy]

Use Class T's everywhere. The House Burned Down thread was using Megafuses.

 

[Zwy]

I tried linking the post but it keeps linking the wrong post.

 

[davewsail]

Use Class T's everywhere. The House Burned Down thread was using Megafuses.

I found the thread and spent hours reading through it. Definitely a wakeup call. Class Ts everywhere then. I'm wondering how to do that to my HEBPs. Each HEBP has 2 battery terminals but they are bussed together. Max hybrid charging current is 240A so 240 * 1.25 = 300A. I think I connect both terminals to a single 300A class T. If so then also 2 same size cables to the busbar? Sorry I know this is basic for you experienced folks but this is my first build.

 

[Zwy]

You can use a 600A busbar like this one which is copper, I drilled into it to ensure it was copper. You can use a pair of Class T fuses coming in or one single 300A with 4/0 cable to one lug, then run the pair of cables to the inverters. Or you can put a custom made busbar right on the Class T holders so there is an ear on each side to attach 2 cables. Only buy Class T holders that have a lug for the fuse and for the cable.

I'm not big on stacking terminals but you could stack on the Class T holder but may have problems with the cover fitting.

 

[davewsail]

So I'm told by Grandtech that my HEBPs haven't shipped because the freight forwarder has too much volume but supposed to ship this week. I
hope this isn't the start of a chain of excuses. On another note, got word that my batteries are shipping out tomorrow as well. They sent me some video of the final testing. Pretty beefy as each module weighs 200lbs, stainless steel shell and internal fire suppression. I have no idea what I'm looking at in terms of the internal cells but maybe somebody here does.

 

[TK1979]

So I'm told by Grandtech that my HEBPs haven't shipped because the freight forwarder has too much volume but supposed to ship this week. I
hope this isn't the start of a chain of excuses. On another note, got word that my batteries are shipping out tomorrow as well. They sent me some video of the final testing. Pretty beefy as each module weighs 200lbs, stainless steel shell and internal fire suppression. I have no idea what I'm looking at in terms of the internal cells but maybe somebody here does.

Those batteries are beast!

 

[doing it different]

So I'm told by Grandtech that my HEBPs haven't shipped because the freight forwarder has too much volume but supposed to ship this week. I
hope this isn't the start of a chain of excuses. On another note, got word that my batteries are shipping out tomorrow as well. They sent me some video of the final testing. Pretty beefy as each module weighs 200lbs, stainless steel shell and internal fire suppression. I have no idea what I'm looking at in terms of the internal cells but maybe somebody here does.

Wow!!! All of those for you? How many watts is that?

 

[NC_hydro]

Looks like 18 x 15kWh batteries, roughly 270kWh

 

[davewsail]

Wow!!! All of those for you? How many watts is that?

No, I've got 8 of them. So 120kwh.