System design assistance

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svsimple asked Jan 24, '20

System design assistance

I currently have 4 Solara 140W solar panels on my boat with a single Outback FlexMax 60 charge controller. I also have the Outback Mate 3S and FlexNet DC, which provide monitoring and data logging, along with multiple shunts.

I'm trying to figure out the best design (and parts) to replace the Outback stuff with Victron equipment.

I understand that due to potential shading, etc, I will get the best performance if I have a dedicated controller for each panel.

Here are my needs and what I think I need. Would really appreciate some assistance in validating this stuff. I've contacted a few resellers, but beyond the simple stuff, like just the controllers, none of them have understood my more advanced requirements.

Requirements:

- I want to have a dedicated solar charger for each solar panel.

- I want to be able to monitor data via TCP/IP (I will write custom code to grab data, but it needs to be network accessible. I do not want to reply on the portal as oftentimes the boat does not have internet access, but the internal network where my login server is located is always online). Data includes solar data generation parameters, battery consumption (see below), battery voltage, battery temperature, etc. I understand the Victron Venus GX data can be accessed via ModBus TCP

- I want to be able to monitor AH added to battery and AH used from battery. I have multiple ways of charging the batteries (solar, AC chargers when docked, and engine alternator). My current system has shunts that monitor these "inputs" as well as the usage from the battery bank. I want to monitor the AH production/usage for all of these individually and collectively.

- I need to be able to configure the charge profile for my type of batteries (12 x Firefly Group 31)

- I want to be able to make changes to configuration remotely.

- I also have Raymarine MFDs (Axiom Pros) that would be cool to integrate

- Space is at a premium, so I need to use the smallest physical gear possible

Equipment I "think" I need:

- SmartSolar 75/15 x 4 (one per panel)

- Venus GX

What I don't know...

Neither of the above has a battery temperature sensor that I could see. How do the charge controllers know how to compensate for the battery temperature?

What about the shunts? Can I reuse the standard 500A/50mV I'm currently using or do I need to replace them to work with Victron.

Any input would be greatly appreciated. Would love to find a vendor who understand the higher level requirements of network monitoring, etc.!

MPPT Controllers VRM

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Modifications Space

Node Red Space

Answer 1 · 2020-01-25T00:29:52Z

Justin Cook answered · Jan 25, 2020 at 12:29 AM

@svsimple, as a general rule this isn't the best forum to find a vendor, but it's definitely the right place to ask technical questions, so you're in good hands :)

To begin with: the Victron BMV-7xx series battery monitor has a single shunt that is the only thing connected to the NEG takeoff of your battery bank, and all load and charger NEGs are connected to the other side of the shunt; in this manner, the BMV measures all current into and out of the battery bank at once. Precise measurements on a per-device level will not be possible without installing additional BMV kits inline with the respective component NEGs; generally speaking, the harvest data reported by each MPPT, for instance, is sufficient detail for most users, so I know of only one other person using multiple BMVs to monitor his system on a per-component basis.

The shunts you have, although the 50mV/500A spec is the same for the BMV-7xx series, are superfluous in a Victron system as the BMV kit comes with its own shunt and I strongly recommend using the one that comes with it rather than any third-party shunts.

Your selected SmartSolar MPPT 75/15s will do nicely for your setup. If you would like temperature compensation, I would recommend either A. the Smart BatterySense to create a VE.Smart network via bluetooth that will communicate battery temperature to the MPPTs or B. the optional temperature sensor for the BMV-702 or -712.

The Venus GX will do well for remote monitoring of your installation through the VRM (so long as you have access to internet connectivity); be advised, however, that it only has 2 VE.Direct ports, so with 4 MPPTs and a BMV connecting to it, you will require 2 VE.Direct cables, 3 VE.Direct to USB Interfaces, and a 3rd-party powered USB hub.

EDIT: As @warwick points out below, an Octo GX would likely be much better suited to your application than the Venus, since the Octo has plenty of VE.Direct ports so you wouldn't need the USB hub and the VE.Direct to USB Interfaces.

For your Raymarine integration, I suggest you refer to the documentation here regarding exactly that; it's fairly simple in fact but may require certain adapters and such depending on your exact system.

Finally, with regard to the ModBus TCP, I refer you to the GX ModBus TCP Manual to start, and device-specific data and communication protocols can usually be found in the Whitepapers section.

Best regards!

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Warwick Bruce Chapman commented · Jan 25, 2020 at 04:17 AM

@Justin Cook will an Octo GX not be more suited in this instance with 10 Ve.Direct ports.

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Justin Cook ♦♦ Warwick Bruce Chapman commented · Jan 25, 2020 at 05:24 AM

@warwick personally agree, actually, but I was thinking in terms of currently available kit; a tentative "early 2nd quarter" release estimate isn't near enough for me to start recommending it yet :-P

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Warwick Bruce Chapman Justin Cook ♦♦ commented · Jan 25, 2020 at 10:14 AM

But the Octo is old? I'm not talking about the new one Canvu?

I have an Octo in my place https://www.victronenergy.com/panel-systems-remote-monitoring/octo-gx

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Justin Cook ♦♦ Warwick Bruce Chapman commented · Jan 27, 2020 at 09:36 PM

Ahhhh jeez, you said Octo and I thought Cerbo *facepalm*, which isn't even remotely similar. No, you're absolutely right, the Octo would work well here! Edited to show that... thanks for catching that!

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Answer 2 · 2020-01-28T21:49:57Z

svsimple answered · Jan 28, 2020 at 09:49 PM

Thank you everyone. I will put together a system diagram in a week or so and post it here for any further feedback. Your time in answering my questions is greatly appreciated!

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