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bombadill asked

Hot Water Diversion from Multiplus II AC-out2 with Relays w/o ac-thor

Question:
I am thinking to run a water heater (as many of here) for the excess solar. Can you explain what problems does the AC-Thor solve in this problem space that the Multiplus II programmable relay does not?

I was planning to program the relay like so:

-Start diverting power from solar to AC2-out when battery is near 95%, and to stop powering the boiler when battery SOC falls to 85%. (or similar values).

Of course this opens the possibility for the system to use the battery to heat, but I would imagine the primary source would be the direct wattage arrived from the solar arrays?

is the ac-thor answering this and bypassing the possibility that the system would use, in some cases the battery to heat up the heater?


also, based on the forum, there has been some problems integrating the ac-thor to the system. I've got two us5000 -batteries and would be interested if anyone has a successfull installation regarding OR suggestions to run excess solar to heaters.

Hot Water Diversion
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2 Answers
pwfarnell avatar image
pwfarnell answered ·

The AC-Thor connects to the export meter and/or other parts of the system and varies the power sent to the water heater to keep export power to zero so it only uses spare solar power left after system loads and battery charging loads are covered. If you only have 1kW spare that is all that goes to the heater, the AC-Thor has a power controller in it. If you use the Multiplus relay and you only have 1kW spare the heater will draw 3kW with 2kW coming from the battery.

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matt1309 answered ·

I have something in between.

Mine's not quite as fancy as PWM controlled water heating to vary power so excess is exactly 0. Which is how i imagine AC-Thor works.

But not quite as basic as using the multiplus relay.

But I have two water heaters of differing load. (One smaller 1kw, and another larger just under 3kw)

I dont use multiplus relay but instead use shelly smart switches to activate the immersion heaters controlled by node red running on the gx device.


A brief explanation of the node red setup:

if(excess power >1000) {

//turn on small Immersioin

}else if (excess power > 2000 && small immersion is on){

//turn off small

//turn on big


}else if (exces power > 4000){

//turn on both

}


Then i've got some more logic to turn off heaters if excess power drops but i add in some buffers so that the heaters aren't constantly switching on and off.


In summary not as fancy as pure dynamic load going into the water heater. But not quite as basic as just one on off switch.

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