Thoughts on my system? Fuses, busbars, battery safety

[MrThisIsME]

It's 89%.
I generally shoot for 85%.
Just depends on how cold it gets in winter in that area.

And there is an argument to forget that and just let the inverter clip. To each their own I guess.

 

[timselectric]

And there is an argument to forget that and just let the inverter clip. To each their own I guess.

Clipping is only on the amperage.
Voltage is destructive.

 

[timselectric]

My Growatt is rated for 450v and can protect itself (by shutting down and throwing an error) up to 500v. Beyond that, it gives up the magic smoke.

 

[badatfarming]

I don't know if you have familiarity with DIN rail stuff but I like that a lot better than the free standing busbars and fuses. It lets you do all the fusing, breakers, etc in a very neat and clean way. Eliminates the need to do a lot of lug crimping. It tends to be very economic. Dinkle DK35N blocks are rated to 150amps (and use jumper Dinkle DSS35N-02P) and your wire gauges.

The smart shunts are the only annoying thing to wire in and mount.

 

[MrThisIsME]

Clipping is only on the amperage.
Voltage is destructive.

Yep. You are correct. Late for me here in the midst of a heatwave.

 

[MrThisIsME]

My Growatt is rated for 450v and can protect itself (by shutting down and throwing an error) up to 500v. Beyond that, it gives up the magic smoke.

I think all inverters are underrated. I have seen a Growatt 3k (rated at 150vdc) run at 162vdc all day long without a glitch, I did not do it It was an RV roof where three large panels would fit and not four.

 

[MrThisIsME]

I don't know if you have familiarity with DIN rail stuff but I like that a lot better than the free standing busbars and fuses. It lets you do all the fusing, breakers, etc in a very neat and clean way. Eliminates the need to do a lot of lug crimping. It tends to be very economic. Dinkle DK35N blocks are rated to 150amps (and use jumper Dinkle DSS35N-02P) and your wire gauges.

The smart shunts are the only annoying thing to wire in and mount.

Never seen the Dinkel line before. Soley I like the jumper blocks they have. I normally use a DIN rail in a suitable box and use solid core for jumpers. The jumper blocks here are much tidier. THANKS!

 

[MrThisIsME]

Posted in error.

 

[MartyByrde]

Without knowing all the lengths, cabling is way oversized. First give away is the 2/0 cable and a 200 amp breaker. A breaker is meant to protect the cable from it's max capacity. From a weak memory, 2/0 cable can handle 900 amps at something like 60 feet. that would be with a 20% voltage drop. 10% drop is something like 35 feet. Find a good DC SAE cable chart and look at your cable runs again. Seat of the pants you could almost wire this up with 6ga, but maybe 4ga to reduce voltage drop.

Given all the batteries I wanted to be extra safe. But you think I’m being too conservative?

Also I thought I could swap out the cables down the road if I needed to, is this a bad practice?

You are also not going to get a 2ga cable into the Growatt 3000, been there done that, the routing is awful.

Good to know this. So 6ga will work?

If there is no expansion planned, take a step back and design cables and breakers for maximum draw (heck if if there is expansion planned, max draw). Right now your max draw is the 3k Growatt and about 70a according to their specs (from memory) and hence why I mentioned 6ga. Also try to keep only one or two cable sizes. Saves on cost of cable, lugs, etc. If you never worked with 2/0 or worse yet 4/0 not fun to route, crimp or deal with in general.

 

[MartyByrde]

Clipping is only on the amperage.
Voltage is destructive.

At 89% VOC max am I running a risk? Temps are highs of 100F summer and lows of 10F winter.

 

[MartyByrde]

Yep, that's on Amazon as well. You may want to email them on that as it conflicts with the NEC chart. The difference may be if they are rated for a much higher temperature which increases ampacity.

Hey I heard back from Windy Nation and the 4/0 are rated up to 440 maximum amperage. In case you ever need.

 

[DurkaDurka]

At 89% VOC max am I running a risk? Temps are highs of 100F summer and lows of 10F winter.

There is a rating for panels that help determine the voltage at different temps - it is called the temperature coefficient. I'm not sure what the average is...maybe .5% per C below 25C.

 

[DurkaDurka]

Hey I heard back from Windy Nation and the 4/0 are rated up to 440 maximum amperage. In case you ever need.

That's great to hear...this must have a very high temperature rating. Probably like welding cable. You can install it and monitor its heat level with a heat gun. If it's too hot, add another one. Hopefully the run is short.

 

[timselectric]

At 89% VOC max am I running a risk? Temps are highs of 100F summer and lows of 10F winter.

Could be close. Just have to watch the DC Bus voltage this winter. If it even gets close, I would remove one panel from each string. This is what I had to do last winter, when I was too high. It was shutting down and throwing codes. Luckily, I didn't loose any of the magic smoke.

 

[MartyByrde]

That's great to hear...this must have a very high temperature rating. Probably like welding cable. You can install it and monitor its heat level with a heat gun. If it's too hot, add another one. Hopefully the run is short.

What temps are considered too hot?

 

[timselectric]

Some say 70c
I prefer to stay under 35c

 

[cs1234]

Some say 70c
I prefer to stay under 35c

Safety people would love you, bean counters would hate you.

 

[MrThisIsME]

That's great to hear...this must have a very high temperature rating. Probably like welding cable. You can install it and monitor its heat level with a heat gun. If it's too hot, add another one. Hopefully the run is short.

It is rated as SAE welding cable. Which is normally low due to the heat they might incur. Plus it is 100% duty cycle. Npt listed here but I think it the SAE measurement is at 100'. Could be wrong.

 

[MrThisIsME]

Given all the batteries I wanted to be extra safe. But you think I’m being too conservative?

Understand safety, but this is overkill. Go price 4/0 cable and you will be in for a shock. Use this chart and make your sizing more correct.

Battery Cable Charts

info.waytekwire.com

If you want to be safe, use the 24v chart for your application. It will bump up the gauge by 1. You also have open terminals with all your open bus bars and fuse holders. If you wanted to be safe, put it in DIN cabinet -no exposed contacts, It will be cleaner and cost less as well. Just make sure the DIN rail breakers are DC rated.

Also I thought I could swap out the cables down the road if I needed to, is this a bad practice?

Not sure what this means.

Good to know this. So 6ga will work?

Since your max load is a 3000k invertor with a draw of ~70amps, I would do the whole thing in 6ga.

 

[sergea]

Hi all,

I will be building this system next week and wanted to thank all the help I’ve gotten from this forum.

I’ve attached a final blueprint for the system (excluding the solar and AC panel box). I’m planning to have approximately 60 to 80 of the Santan solar 240w panels. Five 6S strings into a combiner box for each of the two Growatt SC48120-MPV charge controllers. VOC will be 223.2V versus 250VDC max. Also three 6S strings into the Growatt SPF 3000TL LVM-ES.

Both charge controllers and the inverter are connected to a BlueSea 600A 8-pole busbar. I used Windy Nation ANL fuses 120A (charge controller) and 100A (inverter). And 2 AWG welding cable.

The five 14kw battery packs are LiFePo4 cells (3.2v 280Ah) arranged 16S. They have the 100A Overkill Solar BMS and I’m using 2/0 cable. I have 200Amp breakers for each battery positive wire but I may need to get a 120Amp breaker instead. I don’t want it tripping too easily because then it will overload the other packs.

All five battery packs are paralleled onto separate BlueSea 600A 8-pole busbars. These battery busbars are connected to the inverter/charge controller busbar by 4/0 wire. This 4/0 has Bluesea 400A Class T fuse on the positive wire and Victron 500A Smartshunt on the negative wire.


Inside the enclosed trailer I plan to ground the three combiner boxes, panel box, and the trailer frame to an 8ft copper bar outside the trailer. The three combiner boxes will be inside the enclosed trailer.

The solar panels will be grounded separately to an 8ft copper bar.



Any thoughts are greatly appreciated!View attachment 106173

you may find victron DC lynx power more interesting to simplify your busbars and fuses wiring.

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