So now I have a solar PV system how do I make the most of it???

zeupater

don0301 wrote: »

.... my monitor already overreads, if i adjusted the voltage setting higher, it would overread more. do you still fail to see the point ? ...

Hello again ...

Thank you for editing the previous post by inserting the above information.

I would like to help you out further after providing the above by requesting that you review each and every post and highlight exactly where anyone has recommended that you increase the voltage variable setting within the OWL, it might be found that missed points were really closer to target than given initial credit. I for one have merely suggested that you measure the voltage available in your specific location and set the OWL accordingly, I can't recall anyone else suggesting otherwise either. In addition, I believe that I have also described that large blocks of metal in the vicinity of the split-clamp sensor can effect the field induced in the sensor and therefore create a reading which would normally be considered as being out of tolerance, which could be a contributing factor if the sensor is installed inside the consumer unit ....

HTH
Z

don0301

ok, one last post

just for you, and your persistence

read post 1102, and you will see my fag packet maths calculated my monitor as it is set at 230V is approx 6% overreading the generation meter.

if your assertion that reducing that setting down by 6% would make it more accurate ( in this case 100% accurate,even though the manufacturer states the monitor is only accurate to within 5% at best), then that would put the voltage reading at the exact bottom end of the UK tolerance that you stated. BUT, my home voltage reading is 246.6 today, but we'll come to that in a minute.

i take it you will accept the generation meter is very accurate.

my 6% error maths (fag packet remember, but fairly accurate i think), for me, puts it within the 5% tolerance of the manufacturer's guideline so i would think its hard to argue my maths is wrong. or are you going to argue my monitor is not working properly or something?

i added a nice picture for you to peruse, as you can see my house voltage reading is 246.6V at the moment.

using your "argument" that would mean my monitor (at that setting, 246.6V) would now be overreading by approx 13%. completely out of manufacturers tolerances, and also more wrong, not more accurate than the readings i get now.

so, who's right? the owl manufacturer and the generation meter manufacturer, or you?

happy now?

mickyduck

This is so boring now every post is confrontational back and forwards bickering. I know I don't have to read it but I do have a PV system as I say it was interesting... perhaps we could have another new thread just for people to argue on?

grahamc2003

mickyduck wrote: »

This is so boring now every post is confrontational back and forwards bickering. I know I don't have to read it but I do have a PV system as I say it was interesting... perhaps we could have another new thread just for people to argue on?

Agreed Micky. I've been posting on these boards for several years, and never had any problems with anybody until recently
and never before have I seen such abusive pack behaviour before, on these boards at least. An influx of new posters arrived a few weeks ago, and it has been downhill since. Seems to coincide with many installers being made redundant, and there was a particularly obnoxious installer who used to post trying to drum up business several months ago, and I suspect one of the troublemakers is him in a different guise.

Off topic (ish)By way of diversion, here's a video of a deluded, obnoxious, abusive person who thinks she is something special, like some of the new joiners on here - listen how she reacts when the truth which she can't face is told to her by people who know their stuff, and listen to the comments after she has left ...... Quite a few Rachels on here these days.
http://www.youtube.com/watch?v=7S97pcpVeTA

zeupater

don0301 wrote: »

ok, one last post

just for you, and your persistence

read post 1102, and you will see my fag packet maths calculated my monitor as it is set at 230V is approx 6% overreading the generation meter.

if your assertion that reducing that setting down by 6% would make it more accurate ( in this case 100% accurate,even though the manufacturer states the monitor is only accurate to within 5% at best), then that would put the voltage reading at the exact bottom end of the UK tolerance that you stated. BUT, my home voltage reading is 246.6 today, but we'll come to that in a minute.

i take it you will accept the generation meter is very accurate.

my 6% error maths (fag packet remember, but fairly accurate i think), for me, puts it within the 5% tolerance of the manufacturer's guideline so i would think its hard to argue my maths is wrong. or are you going to argue my monitor is not working properly or something?

i added a nice picture for you to peruse, as you can see my house voltage reading is 246.6V at the moment.

using your "argument" that would mean my monitor (at that setting, 246.6V) would now be overreading by approx 13%. completely out of manufacturers tolerances, and also more wrong, not more accurate than the readings i get now.

happy now?

Hi

Okay, look at it this way then ...

The OWL you have does not measure the Power being consumed or the Energy consumed over time ..... it measures the current passing through the wire and calculates the power as being VxA=W. As you so elequently have stated on a number of occasions this ignores the power factor, this is because the sensor type is unable to measure this, so let's just accept that it's not possible to use the correct full A/C calculation which includes allowance for this.

You have mentioned on a number of occasions that the manufacturer has a stated tolerance for the accuracy of the device, but I would hope that you are able to accept that the Power measurement and therefore the tolerance would be based on setting the voltage which is most appropriate for the location to be monitored ... this would suggest that the manufacturer's tolerance claims are based upon the end user setting the appropriate voltage, as per the instruction manual (See link below).

Taking the above into consideration, if you are seeing a reading with a suitable voltage selected which is 13% out on total energy , remember Energy (Power over Time) not power alone, then there are other likely candidates, including the fact that assuming the tolerance to be Energy based, not Power. The instruction leaflet for the CM119 (http://www.theowl.com/uploads/downloads/CM119_userguide.pdf) states the tolerance on Power as being ....

<1A - Not specified
1A to 3A - <10%
3A to 71A - <5%

... the issue being that for an assumption of the unit to be <5% inaccurate it would need to be seeing a continuous current of >3A, and therefore constantly displaying over 700W, day and night ..... Please also note that the specified tolerances are based on A(Current), not Ah (Current delivered over time), this will be due to the current varying over time which effects the accuracy and specification tolerance banding .... calculating accuracy based on Energy and comparing this to the tightest tolerance band based on Power is simply not logical.

Anyway, regarding power factors on the inverter, the specifications of our inverter type is stated as being 1, as are many inverters in the Fronius range too .... (http://www.fronius.com/cps/rde/xchg/SID-830DF15B-F57B394A/fronius_international/hs.xsl/83_16685_ENG_HTML.htm) , which describes unity power factor, meaning that all Power is delivered as active power (ie no reactive power). The Fronius transformer based inverters in the IG Plus range (http://www.fronius.com/cps/rde/xbcr/SID-830DF15B-F57B394A/fronius_international/TechData_Fronius_IG_Plus_EN_156927_snapshot.pdf) state an operating power factor range of between 0.85 & unity .... obviously someone who knows about generation would be able to help you further, but it seems that a few bridges have been burned recently .....

HTH
Z

zeupater

mickyduck wrote: »

This is so boring now every post is confrontational back and forwards bickering. I know I don't have to read it but I do have a PV system as I say it was interesting... perhaps we could have another new thread just for people to argue on?

Hi mickyduck (/ All)

Sorry if my posts in particular are coming across that way .... I have been attempting to explain what a split-ring monitor does and what the limitations are, as I believe that this is of use to others who would expect to measure Energy production or usage over time ... however, as my 'trollometer' has been flashing red and ringing loud for some time now I'll accept that it's probably correct and stop giving another member the usual courteous 'benefit of doubt' ....

Z

wuthton

zeupater wrote: »

Hi mickeyduck (/ All)

Sorry if my posts in particular are coming across that way .... I have been attempting to explain what a split-ring monitor does and what the limitations are, as I believe that this is of use to others who would expect to measure Energy production or usage over time ... however, as my 'trollometer' has been flashing red and ringing loud for some time now I'll accept that it's probably correct and stop giving another member the usual courteous 'benefit of doubt' ....

Z

You can lead a troll to water but you can't make it drink.

don0301

zeupater wrote: »

Hi

Okay, look at it this way then ...

The OWL you have does not measure the Power being consumed or the Energy consumed over time ..... it measures the current passing through the wire and calculates the power as being VxA=W. As you so elequently have stated on a number of occasions this ignores the power factor, this is because the sensor type is unable to measure this, so let's just accept that it's not possible to use the correct full A/C calculation which includes allowance for this.

You have mentioned on a number of occasions that the manufacturer has a stated tolerance for the accuracy of the device, but I would hope that you are able to accept that the Power measurement and therefore the tolerance would be based on setting the voltage which is most appropriate for the location to be monitored ... this would suggest that the manufacturer's tolerance claims are based upon the end user setting the appropriate voltage, as per the instruction manual (See link below).

Taking the above into consideration, if you are seeing a reading with a suitable voltage selected which is 13% out on total energy , remember Energy (Power over Time) not power alone, then there are other likely candidates, including the fact that assuming the tolerance to be Energy based, not Power. The instruction leaflet for the CM119 (http://www.theowl.com/uploads/downloads/CM119_userguide.pdf) states the tolerance on Power as being ....

<1A - Not specified
1A to 3A - <10%
3A to 71A - <5%

... the issue being that for an assumption of the unit to be <5% inaccurate it would need to be seeing a continuous current of >3A, and therefore constantly displaying over 700W, day and night ..... Please also note that the specified tolerances are based on A(Current), not Ah (Current delivered over time), this will be due to the current varying over time which effects the accuracy and specification tolerance banding .... calculating accuracy based on Energy and comparing this to the tightest tolerance band based on Power is simply not logical.

Anyway, regarding power factors on the inverter, the specifications of our inverter type is stated as being 1, as are many inverters in the Fronius range too .... (http://www.fronius.com/cps/rde/xchg/SID-830DF15B-F57B394A/fronius_international/hs.xsl/83_16685_ENG_HTML.htm) , which describes unity power factor, meaning that all Power is delivered as active power (ie no reactive power). The Fronius transformer based inverters in the IG Plus range (http://www.fronius.com/cps/rde/xbcr/SID-830DF15B-F57B394A/fronius_international/TechData_Fronius_IG_Plus_EN_156927_snapshot.pdf) state an operating power factor range of between 0.85 & unity .... obviously someone who knows about generation would be able to help you further, but it seems that a few bridges have been burned recently .....

HTH
Z

an impressive amount of "information"

yet none of it makes a difference to what my monitor internal voltage is set to, in relation to its readout (which is what you were discussing).......

I'll try to make that clearer, no matter what voltage setting i put into the monitor it will not affect the measurement of current, it will just change the power reading in the display.

re: post 1102

as of 2 days ago

my generation meter was reading as near as damn it 300kWh total

my owl monitor (set at 230V, my setting) after the maths, reading approx 318kWh (approx 6% error)

my owl monitor (set at 246.6V, your setting) after the maths, would read approx 341kWh (approx 13% error). ie less accurate/or put another way more wrong. however you would like to describe it.

its pretty simple.....

Dave_Fowler

Looking back over the last 18 months of readings, I find the OWL meter has almost always read 1.4kWh more each day than the generation meter. It does not appear as a percentage error but a constant error. In December 2010, when the roof was covered in snow, the OWL meter read 1.4kWh or there-abouts each day even though nothing was generated.

I posted earlier in this thread that my OWL reads a constant 67W when the generation has stopped. This is because of a constant mush of noise on the output of the current probe. Most of this is non-50Hz related. If this white-noise mush is truely random noise and is always there, even when generation is active, I believe (40 year old rusty maths) that the readings will always be 67W higher than they should be; Actual generation 2.5kW, reading 2.567kW.

67W * 24hours = 1.6kWh. This is pretty close to the 1.4kWh error I have found in the data files.

Perhaps, once we have had a few sunny days, other PV owners could report on their findings. Is there a constant error which is independent of the actual generation? Obviously you would have to ensure the OWL parameters are set correctly too.

(edit) If there is a constant error, setting the OWL internal Voltage lower than the actual mains voltage will only correct the reading at one output level. It will cause high readings to be reduced too much and low readings will still be too high.

Dave F

don0301

Dave_Fowler wrote: »

Looking back over the last 18 months of readings, I find the OWL meter has almost always read 1.4kWh more each day than the generation meter. It does not appear as a percentage error but a constant error. In December 2010, when the roof was covered in snow, the OWL meter read 1.4kWh or there-abouts each day even though nothing was generated.

I posted earlier in this thread that my OWL reads a constant 67W when the generation has stopped. This is because of a constant mush of noise on the output of the current probe. Most of this is non-50Hz related. If this white-noise mush is truely random noise and is always there, even when generation is active, I believe (40 year old rusty maths) that the readings will always be 67W higher than they should be; Actual generation 2.5kW, reading 2.567kW.

67W * 24hours = 1.6kWh. This is pretty close to the 1.4kWh error I have found in the data files.

Perhaps, once we have had a few sunny days, other PV owners could report on their findings. Is there a constant error which is independent of the actual generation? Obviously you would have to ensure the OWL parameters are set correctly too.

(edit) If there is a constant error, setting the OWL internal Voltage lower than the actual mains voltage will only correct the reading at one output level. It will cause high readings to be reduced too much and low readings will still be too high.

Dave F

as I've said before, mine reads a constant 113W when the inverter isn't outputting. not sure otherwise but interesting point.

I guess they are least accurate in the depth of winter, and most accurate at the height of summer. ie longest daylight, least periods of no generation and more chance of operating in the <5% error range.