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Author Topic: Immersion Heater Diverter Logic  (Read 153 times)
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Posts: 46

« on: November 21, 2020, 02:32:18 PM »

Sorry if this is a bit basic but I have a couple of questions about Diverters. I am currently planning a 5.6KW PV system with 5KW inverter and iBoost diverter

We currently have our immersion heater on a timer set 4am to 6am. In the evening in the winter the water comes from a back boiler on our wood stove.

How would such a set up best integrate with the iBoost diverter?

First, how does the diverter work? Does it just send the excess power to the immersion heater? So if there was 500W spare, is that what is sent down the wire or does it add 2.5KW from the grid to get to the immersion heater rating for the whole period that the ‘over production’ exists (which could be all afternoon, say)

How would my timer work in this set up? On a poor cloudy day, I might still need the immersion heater to come on in the evening if the log stove wasn’t working.

I understand the iBoost diverter has some kind of override switch which might play a role but I’m not sure of it’s relevance.

Finally, for PV systems in general, what visible data is available to the user to monitor system output and consumption. Will I have to go to the inverter in the garage to see what’s going on? The SolarEdge system I have in my shortlist has an app for system monitoring and I understand that the iBoost+ comes with a wireless monitor giving certain information.

I don’t want to over-egg it but I would like to be able to see the situation and decide whether the immersion heater needs to be switched on manually in some way.

As always, very grateful for your thoughts.
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Posts: 1876

« Reply #1 on: November 21, 2020, 02:44:24 PM »

Most Solar diverters work in the same way, there is a current clamp placed on the feed to the main CU and that measures how much power is being exported or imported. The diverter just sends the amont of electricity that would be exported to the immersion heater by basicaly switching on an off very quicklyso only part of a full cycle of electricty is sent.

I can't comment on the iBoost as I have an Eddi, but the Eddi can have 2 thermostats that measure the temperature in the tank, tyically one near the top and one near the bottom. If the top of the tank is below a preset level then diversion is send to that immersion, if the top is hot and the bottom cold then it is sent to the bottom. The Eddi also allows a relay to be triggered so instead of feeding an imersion it could switch on an ASHP for example (there are quite a few settings to control things so for example to prevent short cycling, only turning on when there is a present level of generation etc.). The Eddi also integrates with the Zappi if you are looking to charge your own EVs. The Eddi also allows use of timers so that you could have your imersion run at 05:00-06@30 in the morning to ensure there is enough HW for a shower etc. I believe the manual is online if you want to have a read and get a better idea of what a diverter can do - it has over a dozen example setups. The is also a Harvi in the suite of units which iirc allows monitoring of the various units - but don't quote me on that as I only have the Eddi.
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Posts: 457

« Reply #2 on: November 21, 2020, 05:28:46 PM »

1) The diverters divert exactly the excess power to the immersion. If there is 100W spare they send 100W, and so on.

2) Most diverters also have a “timer” and “boost” function so you can still wake up to a tank of hot water even after a day of poor solar yield or high hot-water consumption.

12x JA Solar 340Wp panels (total 4080Wp)
Lux Power inverter charger
5x PylonTech 2000 2.4kWh batteries (total 12kWh (11kWh usable))
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