andrej avatar image
andrej asked

Multiplus 5000 managing diversion load

Beside solar panells I added small hydro turbine. Batteries are quickly fully charged, so turbine turns without a load...

I know there are diversion load controllers, etc. I was wondering if Multiplus 5000 can be programmed to switch on an AC heater if batteries reach certain voltage (in my case 54V) and switch it off if batteries are discharged to certain voltage level (50V).



MultiPlus Quattro Inverter Charger
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wkirby avatar image wkirby ♦♦ commented ·

@Markus has a hydro system and he has done something with a heater too.
I'm sure Markus would be able to offer more valuable advice!

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markus avatar image markus ♦♦ wkirby ♦♦ commented ·

Hi, yes indeed. But I have my dump loads connected before the MPPT controllers, not to damage them by my turbines high OC voltage.

@valos has managed exactly what @Andrej wants :o) as I have read it in this post:

Best Regards,


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markus avatar image markus ♦♦ markus ♦♦ commented ·

Also @MihaiR presented a good approach to this...

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2 Answers
boekel avatar image
boekel answered ·

You can use one of the assistants to switch AC-2 on/off at certain voltage or SOC levels.

Personally I'd use the 'generator start/stop' assistant (in reverse) so you can also switch off this dump load when other (high) loads are present, so the dump-load doesn't reduce your maximum output.

Another option is to use one of the programmable relays to switch on/off one or more loads (when AC-2 is used otherwise)

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markus avatar image markus ♦♦ commented ·

This is exactly, how i want to manage my water throttling. As you brought me to this idea some time ago. Thanks @Boekel

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boekel avatar image boekel ♦ markus ♦♦ commented ·

You basically get a free PLC with every Multi :)

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spudgun avatar image
spudgun answered ·

I am thinking of going the following route for implementing dump load control in a system with a Pylontech battery and MultiPlus. Any opinions would be welcome.

Use a Solic200 diversion load controller. This can deliver proportional power to the heating element in the water tank based on the current coming from the PV panels. The image shows the sensor before the MPPT but putting it between the MPPT and battery would be better. The diversion to heating element would only operate using the signal (or reverse signal) generator start/stop from the CCGX. Set this to activate based on the battery fully charged voltage. It would energise the contactor on the output of the MultiPlus and allow the Solic200 to start diverting excess power. You would not be cycling the batteries as the power diversion would be based on real time PV power production and only the amount available would be diverted. When voltage lowers then switch the contactor off.

I don't see any reason that this would not work so if there is anything obvious that I have overlooked then I'd appreciate any comments?

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boekel avatar image boekel ♦ commented ·

if you'd put the current sensor at the battery wiring, would it try to keep battery current at zero? that would be ideal.. it then also compensates for loads on the AC side.

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spudgun avatar image spudgun boekel ♦ commented ·

I just found an obvious problem. The Load sensor for that Solic device measures AC and not DC so does not seem to be a viable solution. Back to the drawing board for this project.

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boekel avatar image boekel ♦ spudgun commented ·

ahhh that's too bad...but good to spot now!

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wkirby avatar image wkirby ♦♦ spudgun commented ·

I was going to mention that it's AC only.
Having said that, I do have an AC setup using a Solar iBoost, but I'm on grid ESS. The iBoost is sensing at the grid incoming point and the ESS is set to feed in. This keeps my DC coupled MPPT's at maximum available power all day.

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spudgun avatar image spudgun wkirby ♦♦ commented ·

I think those clamp on AC sensors provide a voltage drop across a resistor and this voltage is proportional to the primary current. If the electronics are just measuring this voltage then I wonder if the electronics would behave the same if the voltage drop was coming from an inline shunt? I'm not sure if the alternating voltage is rectified by the electronics in the AC setup before being measured. Probably not as that would be too easy of a solution.

Another option might be to build a small circuit that measures the DC voltage drop and then generates an AC signal which feeds into the electronics replicating the output that the AC clamp on sensor would be producing.

The MPPT is already measuring the voltage and current so reading that info into an Ardunio from the VE.Direct port and generating a proportional sine wave output to the diversion load controller could work.

Lots of ifs and buts and maybes. Hope to get time to look into this further and hopefully get something working.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ spudgun commented ·

Another option would be to consider some AC bus solar in your system. Find a 2.5kW Fronius or SMA sunnyboy, and put the clamp on the output of that?

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