Can one connect a BMV-712 and four SmartSolar MPPT VE Direct controllers to a CerboGX?

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oceanwolfe asked Dec 15, '22

Can one connect a BMV-712 and four SmartSolar MPPT VE Direct controllers to a CerboGX?

In reading the CerboGX manual (Section 2.3.2: Connecting more VE.Direct devices to your Cerbo GX than number of VE.Direct Ports), I apparently missed that the first sentence indicating 5-connections maximum applied only to the CCGX and that, despite the title of the subsection, there was no maximum given for the CerboGX. If one follows a link in that section that provides the number of connections for several other GX devices (but not mentioning CerboGX as among those), a followup footnote below the linked table finally informs one that the max is for a CerboGX is 3 VE Direct connections regardless of whether they are connected by VE Direct wiring or via USB or VE Can connections. So, it appears my planned four VE Direct to USB adapters connecting the MPPTs to a powered USB hub, then via USB to the CerboGX, won't work.

So, is there a way for me to properly operate my four smallish solar panels (they are on a boat) along with the BMV and a Multiplus Compact through a CerboGX?

I've seen some other threads that play around with the question of 4 MPPT controllers and a CerboGX, but they seem to just end without any resolutions or conclusions.

cerbo gx MPPT SmartSolar

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Answer 1 · 2022-12-15T18:10:50Z

Matthias Lange - DE answered · Dec 15, 2022 at 06:10 PM

https://www.victronenergy.com/live/venus-os:start

Notes:
1. The listed maximum VE.Direct devices on the `Performance` section in above table is the total connected VE.Direct devices such as MPPT Solar Charge controllers.
Total means all directly connected devices plus the devices connected over USB. The limit is mostly bound by CPU processing power. In relation to that, note that (a) connecting solar chargers over VE.Can is more efficient than connected over VE.Direct - and besides more efficient also makes for better communication wiring.
For example, a Cerbo GX can perfectly handle 25 pieces of VE.Can Solar Charger, combined with 6 pieces of Fronius three phase PV Inverter and of course a three phase Victron system. And note (b) that CPU load is not only caused by connecting VE.Direct devices; there are also other factors. Connecting multiple PV Inverters increases the CPU load, especially when they are three phase. Enabling ModbusTCP increases the CPU load as well. Up to three or four three phase inverters can typically be monitored on a CCGX. Higher power CPU devices can monitor more.

Also the manual says 15:
https://www.victronenergy.com/media/pg/Cerbo_GX/en/installation.html#UUID-d0c1e103-df9e-4691-b369-33d047b01491
(maybe you have an older version of the manual?)

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oceanwolfe commented · Dec 15, 2022 at 06:51 PM

Many thanks!

I have manual 1.7, dated Oct 2020, the same time I got the GX, which I've had installed a while. The solar panels and MPPTs are new additions.

The footnote reads pretty much the same as the one you copied.

Is there a way to tell if my older GX still has the limit of 3, or if a software update has increased that, or if it requires a newer GX to get that capacity (or if that limit was just an error to start with)

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oceanwolfe oceanwolfe commented · Dec 15, 2022 at 06:59 PM

OK, I see farther down that same table the part about max number of VE Direct devices being 15 (versus number of ports). I just didn't get that far, thinking I'd hit a dead end already.

Not sure why they footnoted the number of ports, since the footnote doesn't really seem to apply to the number of physical ports. Oh well, many thanks. It looks like I'm good to go on my original plan.

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Answer 2 · 2022-12-15T18:12:27Z

Alexandra answered · Dec 15, 2022 at 06:12 PM

@Oceanwolfe

The limit is 15 devices... so if you have no other devices you will be fine. use the usb to ve direct as well or a powered hub.

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