Need help with wiring size and fuse/breaker size from array to inverter and from battery bank to inverter.

[hotrod]

Ok I am fixing to start installing my parts and pieces I have been collecting over the past 6 months for my off grid solar system for my shop. I have 24 Hyundai 260 watt solar panels (6.24 kw) specs are 260W, Voc 37.9v Isc 8.9a I will be installing them in a 3s-4p 12 panel setup x 2 separate arrays for 2 separate Growatt Inverters - 3120 watts 113.7 Volts and 35.6 amps per array. The 2 Inverters are Growatt SPF 3000 TL LVM 120V split phase 48V off grid inverters. The specs on them are Max PV array 4500W, battery voltage 48v dc, MPPT range 60Vdc to 115Vdc max pv open circuit voltage 145 vdc, max solar charge current 80A and AC charge current is 40A these specs are for each inverter. I will be connecting them together to make split phase 240vac. The Battery bank that I am going to start off with is 2 of the 24v BYD lithium batteries that I purchased from Tech Direct. specs on the batteries are Rated voltage 25.6V, Rated capacity 220Ah Energy 5.632Wh Maximum charge current 130A Maximum discharge current 350A Cell over discharge 2.5V Cell over charge 3.65V 70-80% + capacity
Battery chemistry - lithium iron phosphate (lifepo4) Maximum discharging pick is 500 amp BMS Included. I purchased the cable from tech direct to connect the batteries in series to make the 48v with the 175a anderson connectors when they arrived I noticed the wire for the cable is only a 6 awg wire I have ordered 3 more anderson 175a connectors for 1/0 wire I will be building my on cable for the batteries with 1/0 wire and the 3 new anderson connectors will the 1/0 wire be good enough from the batteries to a 1/0 in to 2- 4 gauge out y block with a 100a anl fuse then leave the y block with 2- 4 gauge positive wires to each inverter and the negative y block the same as the positive to each inverter negative . I am also installing a midnight solar 6 pv combiner box with 20 amp breakers at each array before it heads inside to the inverters. Can you guys look over my set up and let me know if my battery wire is going to be good enough and will the fuses and breakers I have listed work without any problems. I know I need to add a disconnect or breaker between my batteries and my inverters what do you suggest and do I need a breaker inside before my dc voltage connects to my inverters. if so what do you recommend. I am totally lost when it comes to proper wiring and breakers and fuses. Any help you guys can share with me will be greatly appreciated Thanks

 

[snoobler]

Hey hotrod. It would really help if you could split things out. You've essentially posted a wall of text with critical info jumbled in there. A simple list of your equipment one per line, etc., would be helpful.

I honestly don't really know what you're asking because I can't force myself to read through it all. As I read something, I want to reference a prior bit, but I can't find the prior info in the wall of text.

You're asking us to look at your setup, but in order to have any hope of success, we have to sketch out your system diagram for you while plucking it all out of a wall of text and hoping we interpret it correctly.

If you want help, you should communicate very clearly and not ask us to do a bunch of work for you.

If all you need is help with wiring, check the two links in my sig.

 

[hotrod]

Hey hotrod. It would really help if you could split things out. You've essentially posted a wall of text with critical info jumbled in there. A simple list of your equipment one per line, etc., would be helpful.

I honestly don't really know what you're asking because I can't force myself to read through it all. As I read something, I want to reference a prior bit, but I can't find the prior info in the wall of text.

You're asking us to look at your setup, but in order to have any hope of success, we have to sketch out your system diagram for you while plucking it all out of a wall of text and hoping we interpret it correctly.

If you want help, you should communicate very clearly and not ask us to do a bunch of work for you.

If all you need is help with wiring, check the two links in my sig.

Thanks for your reply snoober and I totally agree with you, me trying to explain what all I had, got way out of control I will try to list each item I have separately so its not all running together in a jumbled mess.

 

[hotrod]

Can you guys help me figure out what size wire, breakers and fuses I need to install I've read and watched a lot of videos and I just can't figure out what all I need. I want to make sure I do it right the first time so I don't have any issues.

I have 24- Solar panels 260 watt VOC 37.9 v ISC 8.9 a

I have 2 Growatt SPF 3000 TL LVM 120V split phase 48V off grid inverters. The specs on them are Max PV array 4500W, battery voltage 48v dc, MPPT range 60Vdc to 115Vdc max pv open circuit voltage 145 vdc, max solar charge current 80A and AC charge current is 40A these specs are for each inverter

I have 2 - LFP 24V 5.63 kwh 220 Ah Battery Pack With BMS 130A LiFePO4

Items Parameters
Rated voltage 25.6V
Rated capacity 220Ah
Energy 5.632Wh
Maximum charge current 130A
Maximum discharge current 350A
Cell over discharge 2.5V
Cell over charge 3.65V
70-80% + capacity
Temperature protection 65℃
Battery chemistry - lithium iron phosphate (lifepo4)
Maximum discharging pick is 500 amp
BMS Included
Size Module: 380*197*475(mm) 11"H x 17" W x 22" D
73 kg - 161 Lbs

I have 2- midnight solar 6 pv combiner box with 20 amp breakers at each array before it heads inside to the inverters

I have a Anderson SB 175 to SB 175 Y Series cable 36" 24v to 48V 6 awg wire size

I have 2- DIGITAL LED DISPLAY GOLD 2 ANL FUSE HOLDER 1-0, 2- 4 GAUGE 100A fuse 1 for Positive and 1 for Negative

 

[snoobler]

Much easier to digest. Thank you.

Need a few more details.

1) With two batteries and two inverters and two combiner boxes, do you essentially have two systems side-by-side, or are they paralleled?

Guessing:
2) 1 2S6P array into one growatt, the other 2S6P array into the other growatt.
3) Growatts working in parallel with each other to provide 6kW of 120V or 240V split phase output.
4) 2 batteries in parallel feeding both growatts or 1 battery each feeding one growatt?

5) I don't see how your array is configured, but I glean from the combiner box, you have a 2S6P X2 arrays with each array going into a combiner box. If you have 20A breakers for each two panels in series (6 breakers per combiner box), that's fine. If you have a single 20A breaker from each combiner box, that's not enough.

(6) Where is the Anderson?
(7) where are those 100A fuses?

Observations:

Battery:

11.26kWh of battery is a bit on the low side for 6240W of panels, but you're still well within the 130A charge limit on the batteries. The inverter manual recommends about 20kWh of battery for two inverters (probably assuming FLA/AGM batteries). This isn't really an issue, but the array is capable of about 30kWh of energy per day (assuming 5 hrs irradiance). If you plan to pull a lot of load only during solar hours with very low battery usage in non-solar periods, it should be great.

Inverters:

The Growatts are listed at 11.5kg for 3000W units. In comparison, my Victrons are 30kg for 4000W units (almost 3X the weight for 33% more power). Also, the Victron is ONLY an inverter/charger. It does not provide an integral solar controller. The quality of an inverter is proportional to its weight. The Growatts as combined units are very lightweight. I would be concerned about the longevity and surge capability of these units. If you only use them at under 2kW total, and you don't rely on the surge rating of the units, that would likely improve service life.

 

[hotrod]

Will the

Much easier to digest. Thank you.

Need a few more details.

1) With two batteries and two inverters and two combiner boxes, do you essentially have two systems side-by-side, or are they paralleled?

Guessing:
2) 1 2S6P array into one growatt, the other 2S6P array into the other growatt.
3) Growatts working in parallel with each other to provide 6kW of 120V or 240V split phase output.
4) 2 batteries in parallel feeding both growatts or 1 battery each feeding one growatt?

5) I don't see how your array is configured, but I glean from the combiner box, you have a 2S6P X2 arrays with each array going into a combiner box. If you have 20A breakers for each two panels in series (6 breakers per combiner box), that's fine. If you have a single 20A breaker from each combiner box, that's not enough.

(6) Where is the Anderson?
(7) where are those 100A fuses?

Observations:

Battery:

11.26kWh of battery is a bit on the low side for 6240W of panels, but you're still well within the 130A charge limit on the batteries. The inverter manual recommends about 20kWh of battery for two inverters (probably assuming FLA/AGM batteries). This isn't really an issue, but the array is capable of about 30kWh of energy per day (assuming 5 hrs irradiance). If you plan to pull a lot of load only during solar hours with very low battery usage in non-solar periods, it should be great.

Inverters:

The Growatts are listed at 11.5kg for 3000W units. In comparison, my Victrons are 30kg for 4000W units (almost 3X the weight for 33% more power). Also, the Victron is ONLY an inverter/charger. It does not provide an integral solar controller. The quality of an inverter is proportional to its weight. The Growatts as combined units are very lightweight. I would be concerned about the longevity and surge capability of these units. If you only use them at under 2kW total, and you don't rely on the surge rating of the units, that would likely improve service life.

1) They will be paralled.
2) 1 3S4P array into each Growatt inverter ( 3120 watts 113.7 Volts and 35.6 amps) would it be better to go with 2s6p arrays to each inverter
3) 6kw of 240v split phase output.
4) 2 24v batteries in series to make 48v then 48 volts to both Growatt inverters that's why I'm using the y blocks 1 48v positive in and 2 48v positives out 1 to each inverter, and 1 negative in and 2 nagatives out 1 to each inverter. Inverter manual says both inverters has to be connected to the same battery bank.
5) 4 strings of 3 panels going to each combiner box each string will be connected to its own 20 amp breaker. So I should have 2 20 a breakers in each combiner box not used.
6) The 24v BYD batteries from tech direct came with a 175a Anderson plug already wired with 6 gauge wire to the + and - post on each battery. I ordered the 24v to 48v series cable from tech direct to connect to each battery to make it 48v, The cable I ordered from tech direct came with the 175a anderson plugs but they used 6 gauge wire on the whole thing. So I am going to build my own cable with new 175a Anderson plugs and 1/0 wire
7) The 100A fuses are in the y blocks from the battery

Battery I will be adding more batteries after I get this up and running and see how well it does.

Inverters My shop uses around 15 to 20 kwh per day in the summer mostly for my inground pool and my EV car Chevy Volt charging, lights don't account for much they are all led and a few hand tools from time to time. When it gets winter time I will have to rely on battery storage to charge my car because it will get dark with in a hour after I get home. The inverters will also supply grid power if there isn't enough solar output or battery capacity. I think they will work just fine for now.

I'm hoping in a year or two to install more panels with the Enphase IQ7 micro inverters and the envoy grid tied to run most everything in my home except electric dryer and 4 ton heat pump ac hot water heater and stove are LP gas.

 

[snoobler]

2) 3S4P was fine. Your combiner box/fuse count had me guessing.
4) Okay. so you currently have 1 48V 5.63kWh battery - Defintely light but fine for starters and future expansion. Would expect them to be on the same bank. Just making sure.
5) So 1 20A breaker per 3 panels in series - good
6) For max power, I'm seeing 125A. 150A fuse/breaker
7) recommend 2awg and 125A fuse/braeker.

The total usage looks good for the panels if you can use that power during daylight. If you have a Level 2 charger for the Volt, that can pull a lot of power. Even at the bottom end, a 12A L2 charger, you're pulling 3kW. Granted, that will be split across the inverters, but another 120V load like a pool pump could easily put one of them near their limit.

 

[hotrod]

2) 3S4P was fine. Your combiner box/fuse count had me guessing.
4) Okay. so you currently have 1 48V 5.63kWh battery - Defintely light but fine for starters and future expansion. Would expect them to be on the same bank. Just making sure.
5) So 1 20A breaker per 3 panels in series - good
6) For max power, I'm seeing 125A. 150A fuse/breaker
7) recommend 2awg and 125A fuse/braeker.

The total usage looks good for the panels if you can use that power during daylight. If you have a Level 2 charger for the Volt, that can pull a lot of power. Even at the bottom end, a 12A L2 charger, you're pulling 3kW. Granted, that will be split across the inverters, but another 120V load like a pool pump could easily put one of them near their limit.

On no. 6 125A, 150A fuse/breaker where are you saying to install this one
On no.7 2 awg wire are you talking about where I have the 4 awg wire on my drawing from the y block to the inverter ?

Also after I leave my combiner box and go inside to my inverter do I need a breaker or a disconnect at my inverter if so what do you recommend for that.

 

[snoobler]

You will have 125A going through 100A Y Block fuse.

 

[hotrod]

View attachment 19217

You will have 125A going through 100A Y Block fuse.

Ok thank you so much for your help on this
My inverter manual is saying that I need to run a 6 awg wiring from my combiner box to the inverter what amp size breaker do I need inside before it enters the inverter I would like to use a Bussmann ?A ?Vdc Weatherproof Manual Reset Circuit Breaker at each inverter and do I need 1 on the positive and the 1 on the negative wire, everything I can find is only good for up to 48 volts dc can you suggest a breaker size and brand for this. Thanks again for all your help on this.

 

[snoobler]

Terminology. You have a hybrid solar charge controller/inverter/charger. You confused me for a second by "combiner box" and "inverter". You're talking about the combiner box coming in from the panels to the SCC for the PV connection.

For 80A, 6awg is marginal. If 4 can fit, I'd do 4. In either case, I'd recommend a 100A breaker.

MidNite Solar Inc. Renewable Energy System Electrical Components and E-Panels

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

midnitesolar.com

Rated for 150VDC.

 

[hotrod]

View attachment 19217

You will have 125A going through 100A Y Block fuse.

Hi again snoobler I don't think I mentioned this before when I was telling you that the y blocks that I have bought that I'm wanting to use actually have 2 100 amp anl fuses in each y block 1- 100 amp fuse for each side of the y block. Do I still need to upgrade them to the 125 a fuses.

 

[snoobler]

If that's a 100A fuse for each branch, then it's fine.

 

[hotrod]

If that's a 100A fuse for each branch, then it's fine.

Thanks for all your help

 

[JonL]

I’m hoping mine is a simple question:
I have two arrays. 4, 150 watt 12v panels tied in series/parallel to 24 V. The second string is 3, 300 watt 24v panels tied in series.
both strings go down to a combiner box where I have two breakers at 150 VDC at 15 amps. Do I have the right size breakers?
Files attached. Thanks

 

[snoobler]

array 1 is 17A
array 2 is 9A.

a 15A breaker is inadequate for the first array unless you have one on each series string.

If you're paralleling those two arrays, that's a bad idea.

 

[JonL]

wouldn’t the first string at 24 V lower the breaker fuse number?
Both breakers are 150 VDC and 15A. So I’m using a breaker on each string or array. The first string is 4 150w 12v panels wired in series parallel to 24v. This uses one breaker at 150 VDC 15A.
The second string is 3, 300 W 24V panels, with a separate 150 VDC 15A breaker.
All wiring is 10 gauge. I added another photo of the combiner box.

Soon I plan to add four more panels at 320 Watts. These will be tied in series with a Separate charge controller. Not sure what fuse to use on this one either? Thanks.

 

[snoobler]

2S2P means double voltage, double current. Your array is 45Voc and almost 17A. 15A isn't suitable for 17A

The breaker voltage rating is to ensure it can overcome the DC voltage. DC voltage contacts have an attractive force between them vs. AC voltage, which oscillates to 0V 60 times a second, so it's much easier to break contact.

You're completely crippling your 900W array. At best, you'll get half that.

Panels/arrays in series need the same current.

Panels/arrays in parallel need the same voltage.

You have a 36Vmp array in parallel with a 66.4V array. You'll pull the 66.4V array down to the lower voltage.

You have at best a 1050W array, 600W of 150W panels and 450W of 300W panels.

 

[JonL]

I always thought that going from 12 to 24 V on wiring gave less resistance, halfing your fuse?
I put both arrays at 24 V.
So what breaker should I use for the 600 Watts? ? thanks

 

[Hedges]

Your fuse should be whatever the PV panel label says (15A in this case) and should carry the current for just one panel. Or one series string of panels.

If you have two strings of panels in parallel (e.g. 2S2P) you usually don't need fuses.
If you have 3 or more strings (e.g. 2S3P) then each string of two should have a 15A fuse.

 

[JonL]

Well now I’m really confused, as you and the other fellow are telling me the opposite? ?

 

[Hedges]

Why do you have "3, 300 watt 24v panels tied in series"? What does that go to?

Open circuit voltage will be about 115V on a typical day.

You could connect 2, 12V panels in series, 2 more 12V panels in series. Each of those will be 24V nominal.
You could parallel those two strings and the 3, 24V nominal panels, so you have 1500W at 24V nominal. use 5 fuses.
That would work for some batteries, some charge controllers.

 

[Hedges]

Well now I’m really confused, as you and the other fellow are telling me the opposite? ?

Listen to me. They don't know what they're talking about.
(or, I'm confused)

What do you want to power with these panels? There are many ways to skin a cat.

Seriously, though, most of us here are pretty familiar with the usual techniques and pitfalls. With some differences in "experience."

 

[JonL]

Listen to me. They don't know what they're talking about.
(or, I'm confused)

What do you want to power with these panels? There are many ways to skin a cat.

Seriously, though, most of us here are pretty familiar with the usual techniques and pitfalls. With some differences in "experience."

I went by diagrams I saw on the Internet, they showed where you could hook up for panels at 24 V in series parallel. I want to make sure my charge controller can handle the wattage.
i’m using a Renogy 60A charge controller with limitations of 1600 W at 24 V.

 

[Hedges]

Do you want to put all panels on one charge controller if you can?

First rule is never exceed maximum voltage spec of charge controller.
The sum of "Voc" specs of panels in a string is voltage under typical 25 degrees C, but voltage goes higher on cold days.

Have a link to full specs of that charge controller? You have 1500W of panels which might all fit on it, but I suspect 24V nominal may have enough voltage on a hot day.