SBMS120 and Victron SmartSolar MPPT Charge Controller

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Tim D.

Jul 17, 2021, 7:37:44 PMJul 17
to electrodacus
I've been rethinking my camper solar design and had a few questions

I was planning on using three 100W Sunpower Flexible 12V panels and my SBMS120 connected to a 12V 310Ah LiFePO4 battery but now I'm wondering if I'd be better off using a larger 400W 24V glass panel instead

The Glass panel should last much longer than the Flex panels, and it's cheaper for more wattage. I guess I'm a little worried the Flexible panels will only last a few years so I wonder if it's best to scrap the flex panel idea and just go with a glass panel from the start 

I have enough room to install one 400 watt glass panel

Only problem is my Battery is 12V and the panel is 24V, so I would need to use a MPPT Charge Controller to bring the panel voltage down to battery voltage 

I've been looking at the Victron SmartSolar 100V 30 amp MPPT charge controller

Would it be possible to control this charge controller with the SBMS120?

It looks like Victron sells a Cable that should provide remote on/off control of the charger

I'm just not sure if it would work with the SBMS120 nor am I sure how I would hook up the MPPT charge controller to the SBMS120 if I decide to make this design change 

I appreciate any help


Tim D.

Jul 18, 2021, 9:40:55 AMJul 18
to electrodacus

Would it be possible to hook the Victron MPPT charge controller up to the PV1 or PV2 input of the SBMS120 and not worry about using the EXT IO4 to remote control the on/off function of the Victron MPPT charge controller

Dacian Todea

Jul 18, 2021, 12:38:05 PMJul 18
to electrodacus

Victron MPPT will work either controlled with the remote ON/OFF cable you linked to or according to Victron even if connected to PV1 or PV2 (not quite sure but they show connected to BP65). Most other MPPT will be damaged if the battery is removed while PV panels are connected but not Victron they say that will be OK and show how that will be disconnected by the BP65 thus if true they will survive if connected to PV1 or PV2 on the SBMS120.
But why not just get 32 to 36 cell glass panels and then you do not need the MPPT.  Two of those 160 to 200W panels should still be less expensive than one 400W panel + Victron MPPT.

Tim D.

Jul 18, 2021, 4:22:18 PMJul 18
to electrodacus
Thanks for the clarification, the reason I'm thinking about using 24V panels is  they are much cheaper than 12V panels for the same wattage, for example a 12V 175 watt panel is $200 in my area, I can buy a 400 Watt 24V panel for $200. Yes, once I add in the Victron any savings are gone due to the cost of the victron, but I'm not sure if I'm going to stay with 12V for my Camper battery.

I been thinking I might decide to switch over to 24V in the future, because I have been thinking about getting a Small 24VDC Air Conditioner. If I do that it makes sense to switch over to 24V, since my Fridge Freezer can run on 12V or 24V. So I'm thinking that future proofing the design by having a 24 V panel may be a good idea

If I was 100% sure I would stay with 12V, then buying 200W 12V panels would make perfect sense

I have the LiFePO4 cells I got for free and have enough enough to make the switch to 24V if I decide to do that in the future, so no added cost for the battery cost to switch to 24V

If I make a sliding panel holder I can fit 2 of the 400W panels on the roof of my camper, one on top of the other, then slide the bottom one out when at a camp site. This might give me enough solar to run a small 2300 BTU 24V (250 Watt) Zero Breeze Air Conditioner for a few hours at night.

Thanks again

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