48v MPP set up questions

[Daley]

I am looking at buying a mpp solar 5000w 48v 120/240v output all in one.

I have 8 x 160w 12v panels. What would be the best way to wire these to feed the all in one? Series or Parallel ?

Also I plan to use 4 12v 100/ah battle born batteries wired in series as my battery bank.

Maybe a silly question, but to get a 48v feed that I can then step down to 12v for my lights etc do I just run a circuit straight from the batteries ? I don’t see a 48v output terminal on the all in one.

Also, do you run the 110v outlet to a breaker board if you want to power multiple circuits?

Thank you

 

[Craig]

If you have no shading issues I would wire them in series to about 80% of SCC max input voltage then put them in parallel after that.
not sure of your open circuit voltage but since you have 8 panels probably 2S4P if you had nine panels you could go 3S3P.
I say 80% of max SCC Voltage because if its really cold your voltage could spike and you will want some breathing room.

I would hook a 48-12v DC-DC buck converter to battery bank after a fuse or breaker for your DC 12v stuff

yes use a breaker board for multiple circuits.

 

[Daley]

Thank you so much for your response, very helpful.

This may be a silly question, but when running my 8 panels, some in series, some parallel, how do I wire them to the one solar input on the all in one? Do I combine the two circuits?

My VOC numbers came to over 185v so I cannot run them all in series as 145v seems to be the limit for the all in one.

Thanks again.

 

[Craig]

from what you said you can run 4s2p which again I would recommend if you do not have shading problems.

This will keep the amps down and make sure you have no cable size issues


so in your situation you take the panel 1's positive to panel 2's negative then panel 2's positive to panel 3's negative 3's positive to 4's negative
this would make one 4s string do this again with panels 5,6,7,8 now you should have 1 unused positive and 1 unused negative on both strings.

you can get a y adapter to combine the two strings in parallel something like this

https://www.amazon.com/BougeRV-Conn...r&qid=1572389450&sprefix=mc4+y,aps,218&sr=8-5

They also have some to combine multiple strings in parallel such as this
https://www.amazon.com/Signstek-Bra...r&qid=1572389501&sprefix=mc4+y,aps,218&sr=8-9


If you want a diy method you can make a combiner box with a positive and negative bus to tie the strings to then 1 neg and pos out to go to MPP

make sure you add the appropriate breaker or fuse before you get to the MPP

 

[Daley]

Thanks again for all your help.

I have a bunch of things ordered and on the way, few more silly questions.

What size breaker do I want from solar panels to mpp? MPPT is 2x 80amp input.

What gauge cable would be best for connecting batteries in series and also going from battery bank into MPP?

Is there any other safety,monitoring, or protection equipment I might want to install?

 

[Watts247 - Ian Roux]

60 to 115V is the operating Solar Panel voltage range 145V is the max before damage occurs. 115V to 145V - No Charging occurs - dead zone

Page 9 of the manual, (PV Array MPPT Voltage Range 60~115Vdc )

The statement "MPPT is 2x 80amp input. " is not correct, it is 2 x 80A OUTPUT, this is the current that will be sent down the 48V cable to the batteries to charge them.

The input current calculation is as follows PV Wattage / PV Voltage = MPPT PV Input Amps, example, 4kW of PV at lets use 80Vmp = 50A input into MPPT, if that voltage were to be 100V, the incoming current would be 40A, you can look at the AWG wiring charts to see what AWG supports the calculated current.

There are also numerous online volt drop calculators, punch in your wire size, length and current, and you will soon see the % loss in power based on your AWG choice.
So the higher voltage you can make your PV array - UNDER 115Vmp the smaller these cables can be (factoring in the negative temperature coefficient of your solar panels for the coldest days) You will be surprised how much the voltage of those panels can rise on a 0F day vs a 100F day)

Install a breaker or a fuse at least 125% the calculated PV Amps.

Hope this helps a little

Ian

 

[Daley]

Thanks for all the help, I’m getting there!

My battle born batteries and all in one turned up today. I have 4 battle horns, they recommend using CSL500 Surge protection on the negative side when using an inverter over 4kw.
Is this something I need when using an all in one?

 

[Watts247 - Ian Roux]

Hello, as this is a recommendation by the battery supplier, then abide by it. The all-in-one does not make these stipulations, as there are already fuses built into the unit on the PCB (similar to automotive fuses)

Ian

 

[Cayo]

... there are already fuses built into the unit on the PCB (similar to automotive fuses)

Ian

Hello Ian,

Excellent info, appreciate the accessibility.
I am also preparing to install the MPP LV5048.
Page 5 of the manual says,
“it’s requested to install a separate DC over-current protector or disconnect the device between battery and inverter.”
What would MPP recommend using on a 1/0 AWG positive cable?
I have an on/off switch but am wondering about the fuse.

Thank you

 

[Mac6792]

Hello, as this is a recommendation by the battery supplier, then abide by it. The all-in-one does not make these stipulations, as there are already fuses built into the unit on the PCB (similar to automotive fuses)

Ian

Could you tell us exactly what those fuses are and what they're protecting? I'm only aware of the 40 amp ac input breaker on the 24v model. I'd like to keep some fuses on hand in case something blows.