Dual PV array with sbms0

[Miroslav Šmelko]

I am trying to understand how to set up sbms0 for dual PV array. I do not have device yet, therefore it might be bit harder for me to understand.

I have 150ah 24v lifepo4. I have 12 panels with 60 cells. I would like to have three levels.

L1: 4 panels

L2: 8 panels

L3: 12 panels

Page 16 of sbms0 manual describes this settings little bit. I am still not sure what should I do. I would like to receive your comments on my thinking.

1. Set in DMPPT settings (page 1/8) max current charge to 4 *  9A = 36A ? Or what is recommended in my case?

2. Connect first two DSSR0 with 4 panels (L1) to SBMS0 via EXTIO4- and EXTIO4+.

3. Connect additional 4 DSSR0 with 8 panels (L2) to SBMS0 via EXTIO5- and EXTIO5+. I have hard time to understand where are those two pins physically available on sbms0 with wifi module. Can you describe it little bit ?

4. Set in EXT IOx settings (page 3/8) EXTIO4 as type 1 and EXTIO5 s type 6

5. Should I set in EXT IOx settings also EXTIO4 SOC and EXTIO5 SOC? Not sure what those SOC settings are meant for.

Did I miss something related to setting up dual PV array ?

Thanks in advance

[Dave Festing]

I was waiting for Dacian to answer your questions as I want to try this function as well. 

3) You have to place a 10 pin connector, that is included in the package and called CONN_02X05 on page 44 in the manual, either on to the WiFi board or another board in the SBMS0.

5) I think you then set the SOC value to whatever you want the panels to switch at.

> "You can set this at any limit 80 to 90% will be great setting for LiFePO4"

I had my own panel switching setup but it would only do one big charge each morning then drop back to smaller panels for the rest of the day.

This SBMS0 feature is much smarter.

Dave

[Miro]

Dacian responded to me within minutes via email. I was not sure why not here. If that answer is in iterest of others as well, maybe he can add it here as well, or I can do it if that is no problem. Maybe he did not realize question was coming from forum, because we exchanged few other emails as well.

[Dacian Todea]

Dave, Miro,

Sorry sometimes I do not realize that is a forum question as I mostly get emails so when I do not notice that is from forum I may just replay by email by mistake.

My replay to Miro was the one below

1. Yes 36A seems a good choice for your setup even if the 4 panels exceed that it will still stay connected on L1

2. Yes first two DSSR20 with 4 panels connected to EXT IO4 that will be set as type 1

3. The other 4 DSSR20 with the 8 panels connected to EXT IO5 set as type 6  (as soon as you set a type 6 it will know there is a dual PV array and the one set as type 6 is the larger one).

see image below the EXT IO3, IO4 are on the side white connector while the IO5, IO6 are on the 2x5=10pin connector that is not installed next to the 12pin cell balancing connector same type of connector is included just not installed as it may take to much height so you can either directly solder wires or solder that included connector yourself on the same connector there is also an I2C and UART all isolated for the main SBMS you may be able to see the IO5n, IO5p labels 

4. Yes

5. The SOC have no effect with type 1 and type 6 settings they are for type 3 and type 4 only. 

That will be all relating to dual PV setup.

I think Miro asked here about the SOC in the EXT IO setting The SOC in MPPT menu will have an effect on both single or dual PV array as mentioned in manual. First charge each day will be to 100% then all consecutive charge cycle will only be up to what you have set up in the MPPT settings.