Solar DC system review

[88 Fingers Louie]

Hi, i will be building a system for my shed that will service my yet to be built home and workshop in rural Australia
I know the components i have are not ideal but most of it i have bought second hand at auctions and garage sales, so i need to make do with what i have.
Of the items in the schematic, im yet to purchase the combiner box'sand 80a MPPT fuses.
I also have double the PV array including a second Tristar 60 MPPT i just couldnt fit it in the schematic.
Could you experts out there critique my design thus far?

Thanks

 

[John Frum]

If you added wire sizes we could vet the fusing.
ANL fuses don't have near enough breaking capacity for 48 volt LFP batteries.
I suggest class-t fuses instead.

 

[John Frum]

Are you planning to run without BMSs?

 

[John Frum]

Why not do a 6 string combiner box?
Or get a solar charge controller with a higher max voltage so that you can have less strings and higher string voltages.

 

[88 Fingers Louie]

Yes ill be running BMS's just too fiddly to put in the picture.
In regards to the combiner, sorry but i failed to mention that the second PV array are different panels, 190W so i was going to combine post the MPPTs at the main BUS bars

 

[88 Fingers Louie]

If you added wire sizes we could vet the fusing.
ANL fuses don't have near enough breaking capacity for 48 volt LFP batteries.
I suggest class-t fuses instead.

Copy class-t fuses. Thanks
I have a roll of 4mm PV wire but im guessing i should of got 6mm.
0awg battery
6awg MPPT

 

[MisterSandals]

Tristar 60 MPPT

These are GREAT work horses. Depending on how old they are, you may need to upgrade the firmware and create a custom LiFePO4 charge profile. I've done this and have all the docs and settings that I received from Morningstar support. Ask if you need the files or help.

 

[John Frum]

Copy class-t fuses. Thanks
I have a roll of 4mm PV wire but im guessing i should of got 6mm.
0awg battery

200 amp fuses are good for 0 awg

6awg MPPT

6 awg can be fused as high as 100 amps and that is what I suggest.

You have a 400 amp fuse on the inverter circuit so that requires 4/0 awg.

 

[John Frum]

4 mm2 may be ok for the strings depending on round trip distance to the combiner.

 

[88 Fingers Louie]

These are GREAT work horses. Depending on how old they are, you may need to upgrade the firmware and create a custom LiFePO4 charge profile. I've done this and have all the docs and settings that I received from Morningstar support. Ask if you need the files or help.

Yes i would love the files, thanks! The units are 3-4 years old but new unused.

 

[MisterSandals]

Yes i would love the files, thanks! The units are 3-4 years old but new unused.

Yours might be ok in terms of firmware. Its all a matter of whether it has a LiFePO4 battery profile.

Morningstar reprograming for Lithium

I have two Morningstar SunSaver MPPT controllers one of which is used on our teardrop trailer. I bought the SunSaver about 14 years ago as it was the only one that would handle the high voltage from a used grid tie panel. The high voltage panel means we get usable current when it is shaded and...

diysolarforum.com

 

[88 Fingers Louie]

4 mm2 may be ok for the strings depending on round trip distance to the combiner.

Combiner will sit 2m below roof height, the shed is 5m tall and ill run the wires straight down vertically to the combiner then to MPPTS below. i havnt worked out fully how im going to run the panels on the roof yet.

 

[88 Fingers Louie]

200 amp fuses are good for 0 awg

6 awg can be fused as high as 100 amps and that is what I suggest.

You have a 400 amp fuse on the inverter circuit so that requires 4/0 awg.

I was using 80a fuses as the Tristar manual states max 90a.

 

[88 Fingers Louie]

Yours might be ok in terms of firmware. Its all a matter of whether it has a LiFePO4 battery profile.

Morningstar reprograming for Lithium

I have two Morningstar SunSaver MPPT controllers one of which is used on our teardrop trailer. I bought the SunSaver about 14 years ago as it was the only one that would handle the high voltage from a used grid tie panel. The high voltage panel means we get usable current when it is shaded and...

diysolarforum.com

So basically those settings you posted x 4?

 

[MisterSandals]

So basically those settings you posted x 4?

Yes.
These work great. One oddity, and it may be different on a new unit (mine says 2009 on startup), is that when it reaches "full charge", the remote display shows "fault" and the green/yellow/red lights show red flashing.
This was alarming at first but its just how it works and i am happy to have the workaround. Coming up on 3 years of uninterrupted service with these settings.

 

[John Frum]

I was using 80a fuses as the Tristar manual states max 90a.View attachment 124237

https://www.uglys.net/docs/default-source/uglys-documents/errata/uglysresidentialwiring2017_errata_page2.pdf

Fuse protect wires not devices.