PV and wireless energy monitors - conformation required

Hi,

Found this thread useful, but my electric knowledge less than the original OPs, so I just need confirmation!

http://www.electriciansforums.net/p...0915-connecting-energy-monitors-solar-pv.html

So, *IF* my PV array is on a separate consumer unit from my main consumption consumer unit, I should be able to hang my wireless monitors off the cables feeding each individual consumer unit, and one will record generation and one will record consumption. Correct?

Serendipitously, my consumer unit was full and so my PV is on a small 2MCB consumer unit all on its own. Shame I can't get at the cables supplying it to put the clamp on.

My follow on question is: why can't I place my clamps elsewhere on the circuit? I attached my energy monitor to the AC cable as it left the AC isolator switch next to the inverter AND next to the AC isolator switch by the consumer units and in both cases all the monitor reported was 0 watts UNLESS it was really sunny when it showed 11-13 watts!!

Same behaviour with two different models of monitor. Any ideas?

Many thanks,

Alan..

EDIT: Should point out that if I monitor from the supplier meter tails, I get the same issue as the original OP - if I am exporting, the monitor may show 2.2Kwh usage , I only know that it is exporting because a) I'm not using the dishwasher/washing machine etc, and b) it's damned sunny outside!

@Alan did you read my response to your other post?

Have you checked that the monitor is only on ONE of the cables (ideally the 'live') putting it round the twin and earth will give you an incorrect reading.

We're working with CurrentCost at the moment desiging a system to properly monitor output/ useage / import - you need to monitor it at three places and have a particular wiring configuration else you won't be able to get the data.

So,
To Measure the GENERATED Output, put it round the LIVE cable anywhere bewteen the AC Isolator and your existing consumer unit.
To Measure CONSUMED power, you are in trouble... as there is no single cable that you can access. It would be best if the
To Measure IMPORTED power, you are once again in trouble, as there is no single cable that has current flowing one way that you can access.
To Measure EXPORTED power, you are once again in trouble, as there is no single cable that has current flowing one way that you can access.

Solution:
Get the Output from your PV system connected between your exiting consumer unit and the supply meter.
To measure CONSUMED power, now put a detector round the LIVE cable between the PV connection and the consumer unit

As currently available consumer current detection units don't detect the DIRECTION of flow, the ONLY way to see if you are using Imported or Generated power is to do a continuos live monitoring of both these inputs - that's why we're working with current cost, - the outputs will be streamed live to a web based application so that you then have the information that you need.




Now you can measure:
Generated and Consumed, from that because it is live monitoring we will be able to calculate Import and Export (within reasonable accuracy)

(This is schematic for lay people, not electricians )

Worcester,

many thanks for your replies!

I thought there had been a glitch with my first post - I searched for it but could not find it on the forum - ho hum.

Your reply is very useful - yes I was putting the clamp round the whole cable. I will take on board your comments about monitoring the generated power - this is what I want to see.

As the secondary consumer unit has been fitted flush to the original, I can't see much of the cabling going into it, but if I understand you correctly, there will be separate cables feeding to it and theclamp needs to go around the live one of these.

Many thanks,

Alan..