iboost not using all the excess generation any ideas why?

evomatt

Ive had my iboost for a few months now and just noticed yesterday morning that we were generating 400w and the iboost wasnt on (the base usage was only 30w as everything else was turned off inc fridges ect) so i expected 370w going into to heat the cold tank.
So I waited for the sun to come up a bit more and had a look when we were generating 1000w and the iboost was now fluctuating between 500w and 600w so a loss of 400w (which i guess is going back to the grid). I tried moving the sensor clamp to different places and that only made it worse not better (dont know how when the same amount of electric flowing back to the grid through a cable surely cant give different reads in different positions).
So has anyone else noticed this or is the iboost designed to only come on when is exporting over 400w?

EricMears

Not sure what the iboost's limit is but the essentially similar Immersun lets you choose what level of excess power needs to be available before it starts heating.

'Hall effect' metering is never completely reliable so there's always going to be a margin of error. It's much better to ensure that you never buy electricity for your device to send to the immersion heater than to risk letting the device believe its own measurements.

But even so, 400W seems a very generous margin of error.

nigelpm

I think the deliberate threshold is about 200-400W so probably just falling under it each time.

Probably very little point in knocking 100-200W through the immersion anyway - given that heat loss will have more of an effect than that!

pinnks

The Immersun has two thresholds. First you need to be generating about 200W more than you are using before it activates the output and then, once it has turned on you have the adjustable threshold as a buffer to allow the device to do its maths and ensure you never import. The default is 50W.


So, if you are generating 1,000W and using 200W, the Immersun will output about 750W, exporting about 50W back to the grid. This fluctuates all the time as the load changes and can be between 100W and zero. The main thing is that you never import to run whatever is attached to your Immersun.


What I have also noticed with my non PV compliant Owl, purchased pre PV, is that you can sometimes think you should be outputting to the immersion when the Immersun disagrees. I am pretty sure this is not the Immersun and you would not see this if you had a PV compliant monitor. My guess is you haven't noticed that fridge turn on or the Sky box start recording or updating...

travellerboy

Try repositioning the magnetic flow measuring unit nearer to the incomer supply extending the cable if necessary, it will be more accurate.