PV immersion heater proportional control

[echase]

but it can't currently prioritise these relays over the immersion control.

so if you want to switch the relay at 500W, you'd have to have 3500W available before it will switch, until the immersion cuts out. It won't run the immersion up to 500W, then trigger the relay and reduce power to the immersion.

This is something I've been round the houses with for 2 months with Sibert and Greenologic, hopefully there's a firmware upgrade in the offing, but as things stand it doesn't have this functionality.

The new relay equipped version of the Intelligent Immersion provides this function. It measures the export, ignoring the variable immersion load, and switches on its relay at the value you set. Useful for say a heat pump where the user wants it to turn on at 2kW export yet, if the export is less than 2kW, needs all that to go to the immersion. Thus the heat pump gets the priority over the immersion. What sort of application had you in mind for this function?

 

[solar warrrior]

What is the situation with the Power Reducer and the new Immersun on screening the cable to the immersion and presumable between the diverter and the consumer unit?

On the last EMMA model to be released which was similar I was told it required screened cable because the high frequency chopping up of the sine wave to achieve the PWM action resulted in a lot of RF radiated from a standard twin and earth cable to the immersion. The EMMA people knew what they were talking about so would have done this right. The diverter itself may be EMC compliant but when attached to long standard cables it may not be. Placing it close to the immersion presumably helps on that cable but the now longer one back to the consumer unit has pretty much the same current pattern flowing in it so it going to be just as much a radiator. Hence need for screened cable which in many installations would be costly to lay and in my house almost impossible.

The Immersun has some big inductors in it though so maybe they are there to get around this problem.

 

[SibertSolar]

@Solar warrior - I have some feedback about your query, will update on here shortly.

Question re: MKII Immersun, to anyone who might know, is the on-board MF relay designed to work with resistive loads only? Greenologic/4-Noks are developing the App to provide much more flexibility with their on-board relay (time-clock/auto/manual switching etc) but also, more importantly to some installers, the ability to give a priority to the relay contacts over and above the external Power Reducer (immersion) control. The thing to note here though is that the Elios4You on-board relay is able to control inductive loads as well as resistive, hence my question about the Immersun ability to switch only resistive loads...

 

[SibertSolar]

Ok, with regards to the physical connection between the Greenologic Power Reducer and the immersion tank, the Power Reducer EMC certificate shows that there are no emmissions. If you download the full copy of the test report (from here) you can see evidence of this between pages 26 and 32 (horizontal and vertical antenna tests for continued radiated emission). Pages 28 and 31 show the graphical results related to the compliancy.

According to 4-Noks/Greenologic, this aspect of the EMC testing was probably the most difficult and took the longest time to complete. Radiated emissions are the biggest noise problem with PWM modulation technology.

Using screened cable is always useful, of course, and suggested by the manufacturer, but not essential for the Power Reducer from Greenologic.

In terms of noise from the connection between the Power Reducer and the consumer unit, this is not a concern as there shouldn't be any noise/interference in that part of the circuit (not generated by the Power Reducer anyway!)

Hope this helps, let me know if any queries.

 

[Worcester]

Question re: MKII Immersun, to anyone who might know, is the on-board MF relay designed to work with resistive loads only?

It's an MF relay

If has zero volt contacts so could be used to switch any load.

If you feed it with a proportionally controlled supply, then it applies to whatever load you can put on a PWM controlled circuit, which I presume means resisitive?

 

[Dan]

Don't mind me while I bump some threads in the solar PV forum. If they're not current or applicable topics, just ignore the threads; they'll drop off the page. If they are, feel free to chip in and chat solar stuff in the solar panels forum.