bkenergy avatar image
bkenergy asked

Venus/Multiplus Relay to control a geyser

Hi. I would like to control a geyser with either the Venus relay or Multiplus relay. The relay must close when the batteries are full and there is enough PV coming in from a PV Grid Tie Inverter(ABB).

Is there a way to do this?

Multiplus-IIVenus GX - VGXRelay
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Pat Davitt avatar image Pat Davitt commented ·

I have nothing to add, but I find this discussion fascinating. I assume you are talking about geothermal energy conversion to electrical power, and it's control. If not, what is a "geyser" in this frame of reference?



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wkirby avatar image wkirby ♦♦ Pat Davitt commented ·

Hi Pat

Sorry about the confusion. In Southern Africa (I'm originally from Zimbabwe) a geyser is the term used to describe a hot water heater.

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Pat Davitt avatar image Pat Davitt wkirby ♦♦ commented ·

Thanks, love the colloquialism. That makes sense if you have ever seen a pop-off valve on a water heater go. I live in the US and when someone mentions geyser, I think of "Old Faithful" in Yellowstone National Park.


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1 Answer
wkirby avatar image
wkirby answered ·

Controlling a geyser is not something that is available directly from a Venus device of Multi.
Due to so many different parameters for geyser element power ratings and PV power ratings it's difficult to implement - but it would be nice. There are methods to do this on a case by case basis, taking readings from the Venus device over ModbusTCP and using that data to be processed with your own custom device.

Another method, the one that I use, is to use an external unit which monitors if any energy is being exported to the grid. If so it will PWM control the geyser element with just the that amount of power to prevent grid export.
Something like this:

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bkenergy avatar image bkenergy commented ·

Thanks. the relay would be controlling a normal 230V contactor, so no load on the relay.

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Paul B avatar image Paul B bkenergy commented ·

If its just a relay on and off you could use the gen autostart feature in the Venus to turn the venus relay off and on using the voltage or the SOC conditions to control when on and when its turned off.

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