Help seting up small offgrid setup

[Pana]

Hello Everyone

So far i only have parts nothing is put together.
12v system
I have a 12v 300ah kings battery
kings 3000 watt inverter
victron shunt
victron 150/70 tr mppt controller
victron charger 30amp
My solar panel setup will consist of
3x190w panels in series
3x190w panels in series
both of these will be in parallel
I am very new to this.
A couple of things first
trying to work out the wire sizes i will need between battery and inverter and also for the controler.
Now the bloke i spoke to that was suposed to be the guru of solar when i picked up the victron products said to me that 8mm twin wire was enough for the wire size.
He also said i should have bought 3x100amp batteries instead of 1x 300 amp battery due to something about bms ???????
By doing some research i worked out 3000w inverter/12v batt =250amp
250amps x 1.25 as a safety =312.5amps
that means i will need a cable that can handle at least 312.5amps max
Can someone tell me if i am geting this correct?

 

[sunshine_eggo]

victron 150/70 tr mppt controller
3x190w panels in series
3x190w panels in series

6*190W = 1140W

1140W/12V = 95A
1140W/14.5V = 78A

You are over-paneled for the controller, but well within specs for expected current limits. What is the Voc value of your panels?

Your array configuration shorthand is 3S2P

He also said i should have bought 3x100amp batteries instead of 1x 300 amp battery due to something about bms ???????

Disagree.

By doing some research i worked out 3000w inverter/12v batt =250amp
250amps x 1.25 as a safety =312.5amps
that means i will need a cable that can handle at least 312.5amps max

Yep.

Another method - 3000/12/.85 (.85 is inefficiency) = 294A. Some might also use 12.8V if this is a LFP battery.

1.25 is a good safety factor, and you'll want to apply another 1.25X multiple when selecting fuses/breakers.

 

[Pana]

6*190W = 1140W

1140W/12V = 95A
1140W/14.5V = 78A

You are over-paneled for the controller, but well within specs for expected current limits. What is the Voc value of your panels?

Your array configuration shorthand is 3S2P



Disagree.



Yep.

Another method - 3000/12/.85 (.85 is inefficiency) = 294A. Some might also use 12.8V if this is a LFP battery.

1.25 is a good safety factor, and you'll want to apply another 1.25X multiple when selecting fuses/breakers.

Hi the Voc is 45.2 volts and yes 3s2p config
Yes it is an LFP battery
these are the specs on the back of the panels they are all the same
Max power 190w
current at pmax (IMP) 5.21a
voltage at pmax (VMP) 36.5v
short circuit current (ISC) 5.60a
open-circuit Voltage (VOC) 45.2v
power tolerence range 45+-2 c

Nothing is connected everything is in parts at the moment i am trying to get some help so i dont stuff things up
so your saying i need to get a bigger controller or reduce the panels? If i leave it as is will it be ok?

 

[Pana]

Hi the Voc is 45.2 volts and yes 3s2p config
Yes it is an LFP battery
these are the specs on the back of the panels they are all the same
Max power 190w
current at pmax (IMP) 5.21a
voltage at pmax (VMP) 36.5v
short circuit current (ISC) 5.60a
open-circuit Voltage (VOC) 45.2v
power tolerence range 45+-2 c

Nothing is connected everything is in parts at the moment i am trying to get some help so i dont stuff things up
so your saying i need to get a bigger controller or reduce the panels? If i leave it as is will it be ok?

May i should go 2s2p
760/14.6x1.2=62.4amps
my controler is a 150/70amp so it doesnt run flat out all the time

 

[sunshine_eggo]

Nothing is connected everything is in parts at the moment i am trying to get some help so i dont stuff things up
so your saying i need to get a bigger controller or reduce the panels? If i leave it as is will it be ok?

It is okay. Over-paneling Victron controllers is common. Two rules:

1) NEVER exceed 150V in any conditions (cold weather increases panel Voc)
2) Don't exceed the PV input current limit value on the datasheet. - even at 3P, you're inputting < 20A

May i should go 2s2p
760/14.6x1.2=62.4amps
my controler is a 150/70amp so it doesnt run flat out all the time

You figured it out, don't go over 2S on the controller or consider getting 60 cell panels (36-40Voc) rather than 72 cell.

2S3P would work. You're not over-paneled by a concerning degree. First, Victrons are designed to run at max power for as long as needed. If they overheat internally (rare), they throttle back on their own. Second, MOST of the time, your panels will be putting out < 100% power except in ideal conditions, so you probably won't max out the controller for more than a couple hours/day and not every day.

 

[Pana]

It is okay. Over-paneling Victron controllers is common. Two rules:

1) NEVER exceed 150V in any conditions (cold weather increases panel Voc)
2) Don't exceed the PV input current limit value on the datasheet. - even at 3P, you're inputting < 20A



You figured it out, don't go over 2S on the controller or consider getting 60 cell panels (36-40Voc) rather than 72 cell.

2S3P would work. You're not over-paneled by a concerning degree. First, Victrons are designed to run at max power for as long as needed. If they overheat internally (rare), they throttle back on their own. Second, MOST of the time, your panels will be putting out < 100% power except in ideal conditions, so you probably won't max out the controller for more than a couple hours/day and not every day.

 

[Pana]

You have no idea how much you have helped me so far thank you.
I am nearly there. I have attached the wire diagram so far the only thing left i think is the wire size i need between the inverter/battery and the controler wires also. Are you able to check that i have the fuses correct? Also the circuit breaker between the panels and the controler i have it down as a 20amp 1000v breaker.

 

[sunshine_eggo]

You've already calculated the current for the inverter. Select a suitably rated wire and a fuse 1.25X that - prefer class T fuse since you're using lithium.

MPPT output is 70A max, so use wire rated for 70A and either a breaker or a fuse 1.25X 70A.

You do not need any kind of fuse or breaker in your PV to MPPT connection with 2P. You do with 3P and more. If you want them, that's fine.

Your PV wire must be 1.25X panel Isc.

 

[Pana]

You've already calculated the current for the inverter. Select a suitably rated wire and a fuse 1.25X that - prefer class T fuse since you're using lithium.

MPPT output is 70A max, so use wire rated for 70A and either a breaker or a fuse 1.25X 70A.

You do not need any kind of fuse or breaker in your PV to MPPT connection with 2P. You do with 3P and more. If you want them, that's fine.

Your PV wire must be 1.25X panel Isc.

Ok so for the inverter my calculations where3000w/12=250 then 250x1.25=312.5a so on the diagram i have a 300amp fuse off the inverter and also on the battery that should be enough buffer. the fuse off the controler is 90amps which is good. I want to put a breaker between the panels and controller so i can disable them if i need too is the 20amp- 1000v dc breaker ok ?? for the wire sizes i havent been able to find a chart that i can understand to work out the thickness i need i will have to go to jaycar and tell them what amp rated wire i need and go from there.
What i do have is some 8mm twin wire that might work on the controler side of the wiring not sure what its rated at though

 

[Pana]

Ok so for the inverter my calculations where3000w/12=250 then 250x1.25=312.5a so on the diagram i have a 300amp fuse off the inverter and also on the battery that should be enough buffer. the fuse off the controler is 90amps which is good. I want to put a breaker between the panels and controller so i can disable them if i need too is the 20amp- 1000v dc breaker ok ?? for the wire sizes i havent been able to find a chart that i can understand to work out the thickness i need i will have to go to jaycar and tell them what amp rated wire i need and go from there.
What i do have is some 8mm twin wire that might work on the controler side of the wiring not sure what its rated at though

Can you suggest good quality fuses for what i need