Solar iboost system - being charged for 'free' hot water

Reggieboy2025

Heedtheadvice said:

Ok.

Roughly how long does that increase take?

Do you have any other means to confirm that the display is representing actuality ( or giving you a false reading!) such as from the grid meter?

Suggest now the basic tests from the manual. You could ignore test 2 as that is probably just going to show the problem you have but no harm to confirm that it starts at a power just less than the solar generation level.

Copied to here:

These tests are designed to verify that only excess generation is used by the Solar
iBoost+. Installers must check that increased energy consumption in the home results
in less energy being supplied into the immersion heater. This is indicated in the ‘Heating
by Solar’ display. The availability of high energy appliances (e.g. kettle, electric showers
etc.) are useful during these tests.
 Before testing, if “Tank Hot” displays, run off some hot water.
 Perform tests 1, 2 and 4. When there is no PV generation, perform tests 3 and 4 .
Test 1
When sufficient excess generation is available and “Heating by Solar” is displayed,
check that the Solar iBoost+ stops diverting energy when the PV system is off.
 Shutdown the PV array and the display changes to “Water Heating OFF.”
 Reinstate the PV array.
Test 2
When the PV generation is above 100W, check that switching off appliances in the
home results in greater energy diversion by the Solar iBoost+ unit.
 Shut down all the MCB’s / Fuses except for the PV and immersion.
 Check the level of PV generation on the inverter.
 The “Heating by Solar” level should be approximately 100W less than generation.
 Reinstate MCB’s / Fuses.
NB. If no reading is possible from the inverter a reduction in “Heating by Solar”
value or “Water Heating OFF” should be seen after the MCB’s / Fuses have been
reinstated, switch on a high energy appliance if necessary.
Test 3
At times when no PV generation is available (e.g. commissioning after dark) test the
installation by simulating export energy, achieved by reversing the orientation of the
Measurement Clamp.
 Shut down the PV array
 Reverse the orientation of the measurement clamp (consumption in the home is then
measured as export energy)
 Switch on a kettle or high energy device
 Whilst the kettle is on “Heating by Solar” is displayed and Solar iBoost+ function is
proved.
IMPORTANT! Return the clamp to its correct operating position and reinstate the
PV array.

Test 4....try the boost  action ( just so there is more info about functionality.

It would be useful to do test 3 with something like a 1-2kW heater ( of known power consumption! and eith little else in the house powered) as that could then show you the simulated 'excess' ramping up like with the solar excess problem you have or steady at approx the test piwer consumption level.

 During this test (3) it could be good to unclamp the CT ( measurement clamp ) leave it off the live wire, close the clamp and hold it away from the mains and note the result of that....before replacing it correctly as per the test. The iboost should cease powering the immersion heater at this time as it should not be measuring any excess.

It's usually increased to 3kwatt after 2/3 minutes

Heedtheadvice

Would you give the results of what happens and what the conditions were ( on/off/display/power etc at the various stages of each test) for each of the tests, just so we are clear and can understand. As an example I cannot be certain what you mean by " the iboost doesn't function at all " and to be sure if the responses during the tests are correct or not. Maybe put comments inline on my post attached above?

Qyburn

It seems very clear the Iboost isn’t behaving as if should. It's not a qustion of "being charged for free hot water", rather the issue is that the Iboost is running the heater at full power even when that means some import.

Interesting that it appears if ramps up the power over a few minutes. If that's correct then it can provide variable power, but for some reason decides not to.

Heedtheadvice

I tend to agree but would just like positive evidence then the OP can go back to Marlec ( or the supplier/landlord) with a case for either replacement or repair  as appropriate.

If the manufacturer's own tests prove that expected fault then there cannot really be any argument that the iboost is not working as it should

Petriix

Almost certainly a ct clamp issue. Ramping up suggests a feedback loop where the more it uses the more surplus it thinks there is until it hits maximum power. We really need to see photos or we're just guessing though. 

Heedtheadvice

Quite right Petrix which is why I queried its fitment and subsequent questions!

We seem to have had no responses now for a while so wonder if the problem has gone away......

Reggieboy2025

Hi guys

Problem still exists, been advised from Marlec (the manufacturer) to try the clamp on a different tail, but cannot fit it on specified cable as there's no room for the clamp, don't know what to do next

Cheers again

Solarchaser

I'd suggest taking the clamp off, turning is 180 degrees and putting it back on.
As it almost reads like you are reading incoming current,  so it turns on, then it sees more, so it increases, then it sees even more and goes fullbore. 

Turning the clamp round the other way, and then leaving it alone for 5 mins, then tuning on your oven will confirm.
If the iboost turns on when your oven turns on, then I'm clearly wrong and it's the right way round , so turn it back.

If it doesn't turn on, then its the correct way now I guess.

Actually after typing all of that, the answer is simpler.
Don't change the clamp.
Turn on your oven while it's still sunny and watch the iboost, if the iboost turns on with the oven on, then clamp is wrong way round

Heedtheadvice

You are quite right Mr Chaser....what you suspect is a possibility  but some of the descriptions  of the 'fault' and answers to questions don't really give enough detail to be definitive. There has been, for example, only an indication that the problem exists when PV  is being generated. That would imply CT OK and main unit faulty - or something else!

So that should be answered by Test 2 that I copied into a post.

I wish Reggieboy  would have answered the questions 'in full' ( to quote Martin Lewis ) and be more descriptive and post pictures where that would help for us to see.

Several of  us have been helping and suggesting along similar lines to check/test and rule things out.

I am wondering if I am wasting time and I am  near the stage of stopping  hitting my head off the brick wall.

Reggieboy please do what Solarchaser suggests. It might be the problem but if it is not the problem lies elsewhere.....and do bear in  mind that it sometimes takes a few seconds for readings to show up correctly.

Qyburn

Reggieboy2025 said:

Hi guys

Problem still exists, been advised from Marlec (the manufacturer) to try the clamp on a different tail, but cannot fit it on specified cable as there's no room for the clamp, don't know what to do next

Cheers again

The CT clamp is labelled to show which way round it should go, assuming it's on the Live tail. It will work equally well on Neutral but would need to be fitted the other way round.