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Problematic Pv Array, Pulling Energy Off Nat Grid.


Rigger

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I've currently got a 4kW PV array on my roof, which is at 165 degrees from North, so only 15 degrees of South - happy enough - no shading issues


 


Panels are 16 Sunmodule SW250 Mono Black, and each panel has it's own Enphase M250 micro inverter. This feeds into a single digital generation meter, then to an isolator. This in turn feeds into the consumer fuse box unit, and is then tied via bus-bars back into the incoming dual export/import meter.


 


Had the system since mid Dec. Nearly 1900 kW generated since then, not bad for this neck of the world!


 


Had an OWL Intuition type 2 system fitted to monitor how much I am exporting to the UK National Grid - recently in the last few days.


 


I've had to do this as my electricity company contacted me to say that my bill was at £800 + - That's Sterling - Not Dollars!!!


 


Fitted the OWL system, and I see straight away yesterday morning, that as the panels start generating more and more energy, the import start increasing too, by roughly half! The export figure was never going to exceed the import.


 


By the time the PV array is showing 2kW/h, my import meter is showing 5.6kW/h. I turn off the PV at the fuse box, and import drops to 0.4kW/h or 442W to be precise.  This proves that the PV array is pulling juice off the Nat Grid.  The whole reason of getting Solar PV was to decrease our lecky bills, and get some money back from the energy we exported back to the grid.


 


Contacted the installer, who is coming round either today or tomorrow, and has said that they will foot the electrical bill. I suppose I'll find out tomorrow how honest he is!  He says that he's heard of this problem, but it's never happened to him (obviously, the cynic in me says).


 


Has anyone else come across this problem before, and what did they do to correct it?


 


 


 


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ProDave

I seem to recall some makes of electricity meter, meter whatever passes in either direction.

 

It's a DNO or energy supplier issue. you need to get them to change your consumption meter for a different one, then unravel how much they have over charged you since your PV was installed (the amount recored on the PV generation meter should help that calculation)

 

it is NOT a fault with your solar PV and there will be nothing that they can fix, only your energy provider can fix it by changing your consumption meter. Though it's good of them to offer to refund your excess usage charge.

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binky

the Owl is set up wrong and is measuring export as import, if your ssytem has generated 1900kWh since December then it is flying along and should be putting big holes in your bills. To do that, you need to make sure you use appliances during daylight hours.

 

In my opinion Owls are rubbish anyway, try a Geo solo display

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ProDave

Read it again. his consumption bill has gone up since the panels were installed.

 

Right, forget the Owl.

 

On a good sunny day, write down the reading of your CONSUMPTION meter mid morning, then write it down again late afternoon.  You would not expect it to increase much if at all on a sunny day when you are generating loads.

 

If it is increasing then it's a consumption metering fault.

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binky

no his owl is wired backwards - we had this on one of my early jobs, when the customer switched his hoover on the 'output fell' - PV is outputting but been seen by the clamps as flowing in rather than out.

 

The most a PV system will add to the leccy bill is about 10watts overnight on standby. Modern didgital meters do not register the output to the grid, unless its an export meter. The installer should have supplied a remote display so the customer can see what is going on with his system, and utilise the energy generated effectively. I suspect if his bills are up, then it's becuase he thinks he's getting all his electric from the panels and has since switched on every appliance like it generated 4kW all day long, when the reality is that is PEAKS at 4 kW somewhere between 10am and 3pm

 

it is possible that his meter is faulty, but Owls and variuos other devices like that use current clamps on the meter tails, which are cheap, and prone to misreading EMF from surrounding electrics

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I've checked the orientation of the clamps already.  I'm 90% sure I've got them the right way.

 

I'll go out and check again though.


Oh - more info.

 

There was initially an old analogue meter in place, which was changed out at the end of March for a digi import/export meter.

 

NIE really were dragging their heels.

 

That was done while I was offshore, so I didn't manage to get a final reading off the old meter, and I don't think the missus did either.

 

Right - off to check clamps again.

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Clamps checked for orientation - 100% correct.

 

Even Power NI admitted that the usage was high, since Dec.

 

So - either installer has wired soething incorrectly, or new digi meter installed by NIE is also incorrectly installed.  Unlikely, as everything else seems to be working fine.

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binky

if you had an old meter, then it could have been clocking backwards, in which case they may have estimated your bill, which they aren't allowed to do becuase they can't prove how leccy you used when the meter was going backwards, and can only bill for the leccy they can prove you used.

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ProDave

Forget the owl, that's not what charges you.

 

Do that CONSUMPTION meter reading check on a good sunny day to see if the consumption meter is counting up or not.

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Forget the owl, that's not what charges you.

 

Do that CONSUMPTION meter reading check on a good sunny day to see if the consumption meter is counting up or not.

Will do.  Nice and sunny at moment.

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binky

quicker version, switch off all circuits bar PV at board and watch what you meter does

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(( Shouldn`t have let them change that old meter - some customers have to fib through the summer, about the readings - because it goes down, month-on month; then catches up again over the winter. Newer meters - not as good. You get charged the import and export, according to the tariffs in force - with the analogue meter, you were being paid for export at the same rate is your import tariff - if you know what I mean?))

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Have been monitoring the import/export meter against what the Enphase system has been saying has been generated.

 

Clamp orientation was correct - 100%, but out of interest, I turned it round - the wrong way according to the OWL manual, and hey presto - got correct readings.

 

Waiting to see how OWL support comment on this one!

 

@ KME - As for the meter being changed out - Power NI wouldn't touch the system unless there was a certified import/export meter so that OfGen could then verify that ROCS payments could be made.  For some reason - N' Ireland has different set up to rest of UK.

 

Didn't help that I was offshore also for extended period of time.  I've only been home 7 weeks this year!

 

I realise the short-comings with the OWL system, but it does let me check how my system is doing from anywhere around the world.  I'm also using it as a guide - not a definite gauge.  I also compare it with the Enphase system, which is slightly more accurate - again I can do this online from anywhere.

 

Others have said to get other systems - not now - the owl system is bought and installed.  Not perfect - granted - but it serves a purpose as a indication of what my system is doing.

 

Have also checked wiring as far as visually possible with import/export meter - Landis+Gyr E110 - 5235A.  Wiring diagram on internet looks quite basic, and appears to be correct.

 

Next step is to find out final readings of old meter from NIE, and make sure that Power NI have adjusted for that.

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Hi Rigger, have you done as pro dave suggested and check to see if your normal usage meter for your leccy added any units on today when the sun was shining.

Just to confirm presuming your house load is less than what you are generating then your normal meter should show no additional units and your generation meter should have say an additional 15 or so units on it depending on how sunny it was in Ireland. If your normal usage meter is showing this 15 units as well then you still have a meter problem.

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Hi Rigger, have you done as pro dave suggested and check to see if your normal usage meter for your leccy added any units on today when the sun was shining.

Just to confirm presuming your house load is less than what you are generating then your normal meter should show no additional units and your generation meter should have say an additional 15 or so units on it depending on how sunny it was in Ireland. If your normal usage meter is showing this 15 units as well then you still have a meter problem.

Yeah - did that today.

 

System generated 8kW/h today.

 

That was checked on generation meter.

 

Next to import/export meter.  Export has risen by 5kW, and import has risen by only 1kW.  I'm thinking this proves the clamps were at fault, though still waiting for OWL to get back to me on this.  I've sent away photos confiming correct orientation and location by OWL themselves.

 

Scuse - will write later - have to clean fish tank! ;(

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binky

told you so! :slap

 

Pv is made to too many standards to firk up the way you thought it was.

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True binky but could the issue not have been with the DNO meter adding the generated units?

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binky

thye are built to a standard as well and do not register exported solar as energy used. Old stuff clocks backwards, digital meters just break eventually from what I have seen

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Well, regardless of the result, I'll stick with the OWL for reasons stated before - ie working offshore, and being able to monitor what is happening at home.

 

Still, will be experimenting with clamp positions and orientations to ensure best accuracy.

 

We use PT and CT clamps on our high voltage AC units - 3000V single phase and 1703V on each of the three phases.

 

Will be waiting on an answer from OWL as to why there clamps were showing the import and export figures together.

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binky

Chinese translators

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thye are built to a standard as well and do not register exported solar as energy used. Old stuff clocks backwards, digital meters just break eventually from what I have seen

I have to disagree to an extent. I have numerous so called 'tamper meters' that do indeed measure current either way as import. Thus leading to increased bills. Best way to test is the method mentioned above. When it is nice and sunny, turn all circuits off at consumer unit except solar. See if import meter increases. If the bills have increased as stated then that has nothing to do with any ct clamp and I suspect it is a tamper meter. I have seen at least 20 cases of these.

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ProDave

Re electricity meters.

 

My own Siemens meter is an odd one. the red light still flashes when it's exporting but the display does not count up.

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Barx,  good info, but how can I prove it.

 

Import Export meter is a Landis+Gyr E110 - 5235A.

 

Import (t) is showing 1590 Kw and Export ® is showing 506kW.  This meter was installed at the end of March.

 

Power NI - my electricity supplier - would not accept readings from a analogue meter.

 

They said it had to be a dual meter that could show OfGen how much I was exporting from my system to the Nat Grid.

 

My question now is - Is the Landis + Gyr E110 - 5235A a tamper meter - that measures current either way as import, and how can I prove that to Northern Ireland Electricity, and finally to Power NI?

 

Surely the fact that I have two different readings shows that the meter is working correctly?  Or has the import been reading the export reading too?

 

I'll be monitoring the system over the next few day anyways.

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ProDave

Confused meter reader?

 

I had an issue with a rental flat where for about 2 years the meter reader had got the day and night readings for E7 the wrong way round. It took months and 3 meter reader visits to convince them it was wrong.

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binky

ok lets get terminology correct, your solar meter is known as the 'generation meter. it does not measure export, it measures electricty passing through it in one direcion as per any other OFGEM approved meter. If it is wired correctly the inverter will be connected to the left hand side and right hand side connected to your board.

 

The Landis and Gyr model you mention I've fitted hundreds of, it doesn't clock in reverse - could you imagine the fiddling possible for FiT claims if it did. Now its got dark, check it, your inverter system will be pulling about 10-30watts from the grid in standby mode, yet it won't be clocking anything. When we first started solar work, some people I subbyed in to give hand wired the gen meter the wrong way around, they didn't clock backwards.

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