Something does not add up..

[Uklad]

Hope your guys can help with this had my 4 kWh system in since Dec 18 2012 everything is working great but i have just entered my import meter reading onto Scottish Powers site and i don't seem to be seeing much of a reduction in my ele usage

Feb usage = 369 vs generation 142 kWh export measured at 50 kWh
March usage = 366 vs generation 271 kWh export measured at 80 kWh missing a week of data..

I have noticed when i do meter readings at the end of the month the import meter is always showing rEd

 

[Gary K]

rEd stands for reverse energy detected. some meters can be configured to add any energy going the wrong way through it to the used energy reading- it to stop people frauduantly rewiring their meter.
Obviously if you don't use the energy as it is produced, say you are not at home during the day so no usage, then you will not save anything. once it is exported then its gone.

 

[Uklad]

Ahh so my export could be being added to the import meter who fixes that for me ?

 

[Earthstore]

Your energy supplier should arrange for a meter change/upgrade.

 

[whinmoor]

Is your import meter a Siemens?

Or, do you have a pre-payment meter?

 

[liquidity]

But just because it's saying rEd doesn't mean the export is being added to the import.

You give what appear to be import, generation and export figures for Feb and March. Where does the export figure come from?

 

[Uklad]

From my owl PV system everything else is from meter readings

 

[Gavin A]

Is your import meter a Siemens?

This is an important question.

There's an entire batch of siemens meters out there from around 10 years ago that have an anti-tamper setting that means they read both import and export as if they were both import, which would explain your readings.

There may also be other makes with the same issue, but I've not come across them (yet).

 

[FB.]

But just because it's saying rEd doesn't mean the export is being added to the import.

Agreed - I have a Landis&Gyr E110 electricity meter an although it says "rEd" it does not add export to import (neither does it go backwards like the old mechanical meters).

By chance my solar array also happens to have a Landis&Gyr E110 to measure export.


As some people have suggested: perhaps the power generated by the solar is not being efficiently used ("use it or lose it"), but on the other hand some people with solar over-estimate how much it produces and switch everything on (sometimes in a wasteful way), resulting in a lot of power being imported from the grid because the power demands are so high that the solar can only provide a small portion of it.

At the moment, I'm generating about 0.6kW (3.7kW solar array) on a "white cloud" afternoon. My computer is running (0.2kW), the central heating is running (0.2kW for pump/fan etc), my wife is watching TV in the other room (0.2kW) so we're using all it's producing. We just boiled the kettle (3kW) so during that time we were still having to import 3kW of power for five minutes. Not to mention if we were running the washing machine, power tools/garden tools etc.

 

[Uklad]

The generation meter is a Landis&Gyr E110 my import is a Ampy Automation 5235a looks the same

 

[SibertSolar]

They're both effectively the same meter. Your primary/utility/import meter shows rED when reverse (exported) energy is sent to the grid, as others have said. Your system is most probably exporting energy when you need it the least, thus impacting on your imported values very little. You need to store or be smart about how you consume your generated energy if at all possible, in order to reduce your net import.

Just as an aside, how accurate do you believe your Owl monitor to be? I've seen over 20% innacuracy on some systems...

 

[Uklad]

Today my owl has measured 12.1 kWh generated from CT clamps, PVoutput logged from the inverter is showing 12.5 kWh that's a 1% difference in my calculations are correct

Helmshore sun trap ! 4.000kW

I'm not really questioning the smartness of my energy usage, im just not really seeing the difference in my import meter that i would expect based on my generation, maybe it is just me meter configured wrong..

 

[FB.]

I'm not really questioning the smartness of my energy usage, im just not really seeing the difference in my import meter that i would expect based on my generation, maybe it is just me meter configured wrong..

Is your house a high consumer of electricity, and the cold weather has caused you to use more? It is reckoned that gas usage is up by one-third on last year. Quite a few people are looking at their gas and electric meter in recent days (bills due soon) and a lot of people have had a fright at just how much they've had to use to keep warm this winter.
So if you have quite a lot of electric heating in your house, maybe the bitterly cold weather has caused higher usage than last year, but the solar has made a contribution which has kept the electric import about the same.

 

[Uklad]

Ha Ha don`t mention the gas bill holly carp !! with this winter and an extension added to the house in the summer the gas has shot up, i think i will give it another month and do some calculations again and see how it goes

 

[Worcester]

The other thing to consider is that occasionally some installers have incorrectly connected the PV to the WRONG side of the consumers meter, so you're not getting the benefit of anything you generate (except the FiT).

How is your's wired in - a photo would help us and save a dozen posts asking for more detail.

 

[danesol]

Today my owl has measured 12.1 kWh generated from CT clamps, PVoutput logged from the inverter is showing 12.5 kWh that's a 1% difference in my calculations are correct

Helmshore sun trap ! 4.000kW

I'm not really questioning the smartness of my energy usage, im just not really seeing the difference in my import meter that i would expect based on my generation, maybe it is just me meter configured wrong..

Does your OWL work out what your actual export values are ??

As looking at your PVO account - they either arent posted or you have PVO settings set incorrectly ??

As said above - you wont see a great reduction in your electrical bills Jan-Feb and Nov-Dec, especially if your export percentage is high as well.

 

[danesol]

Hope you dont mind, but another observation just looking at your LIVE data - your voltage seems to go a little high - you may have to keep an eye on that when the production really kicks in, as your Inverter may start to shutdown if it gets too high.... assuming that (grid) voltage figure is accurate btw


ps> where is that Temperature value coming from too ??

hth

 

[Uklad]

The data on the PVO is direct from the inverter the TEMP is the inverter temp i think, i can not find a way to link the owl data into PVO.. so the export is just the same as generated.

on a side note about the grid voltage i have noticed its a bit high but for a few days in feb is dropped but came back up

Helmshore sun trap ! 4.000kW | Live Output

Is there anything that can be done about the high voltage

 

[danesol]

The data on the PVO is direct from the inverter the TEMP is the inverter temp i think, i can not find a way to link the owl data into PVO.. so the export is just the same as generated.

on a side note about the grid voltage i have noticed its a bit high but for a few days in feb is dropped but came back up

Helmshore sun trap ! 4.000kW | Live Output

Is there anything that can be done about the high voltage

Well as long as it isn't ambient temperature around the Inverter you are OK

With regards Grid Voltage, just keep an eye on it as it may cause an issue when fully generating, are there any other Solar PV arrays in your surrounding area that you know of on the same sub-station ??

If you do have issues - May onwards, you or your installer could try speaking with your DNO about lowering the grid a wee bit, as I personally found my DNO very helpful when I reported that voltage was too low in our road on every phase ( 216Vac ), however I suppose it did cost them a fortune in my repair bills so may have been over obliging in my case switching the network within 3hrs of the callout ( after checking other random houses in the road on each phase ) but are not obliged to do anything unless its outside std +/- tolerances.

 

[Uklad]

I know of 1 other system that is on the same sub station looks in the region of a 2kWh, i have long had issue with halogens popping way to soon and LED transformers not lasting long..

 

[danesol]

I know of 1 other system that is on the same sub station looks in the region of a 2kWh, i have long had issue with halogens popping way to soon and LED transformers not lasting long..

Well if you do have a voltage issue at some point, check with your neighbours as if they are also experiencing high wear & tear - as you may find that approaching a DNO in bulk, is a lot lot easier with a more favourable result, especially if they have to fork out for replacements like they did with me.

 

[danesol]

Is there anything that can be done about the high voltage

Other than DNO involvement, if its constant high voltage - you could consider one of these as they may suit your situation ;

http://www.electriciansforums.net/p...e-optimisers-pv-array-high-grid-voltages.html

 

[Gavin A]

The other thing to consider is that occasionally some installers have incorrectly connected the PV to the WRONG side of the consumers meter, so you're not getting the benefit of anything you generate (except the FiT).

How is your's wired in - a photo would help us and save a dozen posts asking for more detail.

yeah, rings a bell that one.....:redface:

looking at the figures again, it's not that unlikely that they're actually right though, given the rubbish march we've just had, could be explained by more lights being in use, or something being used more in the house - it's not that different.

Definitely worth keeping a proper eye on it though - we've had to replace a landis meter for someone recently that was reading much higher than it should, we put it on test in series with another meter and it's now reading around 50% higher than the other meter, having worked fine for 3 years.

 

[Worcester]

Definitely worth keeping a proper eye on it though - we've had to replace a landis meter for someone recently that was reading much higher than it should, we put it on test in series with another meter and it's now reading around 50% higher than the other meter, having worked fine for 3 years.

Hope it was his generation meter

 

[Uklad]

Hope it was his generation meter

I was wondering the same

 

[Earthstore]

The other thing to consider is that occasionally some installers have incorrectly connected the PV to the WRONG side of the consumers meter, so you're not getting the benefit of anything you generate (except the FiT).

How is your's wired in - a photo would help us and save a dozen posts asking for more detail.

I considered this too, but if his import meter is showing RED then it must be connected in after said meter.

 

[moggy1968]

contrary to the above your voltage will reduce from may onwards as the panels become hotter. max voltage produced is likely to be about now when the panels are cold.
current is more affected by the amount of light than voltage. Voltage is affected more by temperature

 

[danesol]

contrary to the above your voltage will reduce from may onwards as the panels become hotter. max voltage produced is likely to be about now when the panels are cold.
current is more affected by the amount of light than voltage. Voltage is affected more by temperature

I know what you mean, but your statement is contradicting basic Physics concepts now !

Voltage is effected by temperature but it is an indirect resultant change, not directly responsible, and current is directly influenced by either resistance or voltage which indirectly as you say is effected by things like radiation levels unless that is there are new laws recently discovered - lol

Just looking at his peak figs so far he peaked at 1pm with 3.615w @ 39.6deg at 253.1Vac Grid current - that's abit too high for my liking but you maybe right and it may reduce as the mths go by, but he seriously needs to watch this IMO ??

 

[moggy1968]

I think we might be ssaying the same thing in a different way danesol:smilielol5:

voltage is affected by the amount of irradiation but, not as much as current and the temperature of the panels in the summer will reduce their voltage output. at the moment, when sunlight is bright with little atmospheric polution but the air is cold panel voltage is likely to be at it's highest. After May it will probably be less.
The systems we have done I have figures for tended to max ot mar/april last year, not in the summer and thats because of the effect of temp on voltage.

basic physics is lab based, actual real life is not.
The laws of physics tell us a rock will fall at the same speed as a feather, but in real life they don't because of the presence of other factors!

 

[danesol]

basic physics is lab based, actual real life is not.
The laws of physics tell us a rock will fall at the same speed as a feather, but in real life they don't because of the presence of other factors!

They do in a vacuum, plus terminal velocity of all items falling to earth not acted upon via other forces will be the same :tounge_smile:

Now lets get back to Ohms Law ...... lol

 

[Gavin A]

Hope it was his generation meter

me too...

 

[Gavin A]

They do in a vacuum, plus terminal velocity of all items falling to earth not acted upon via other forces will be the same :tounge_smile:

Now lets get back to Ohms Law ...... lol

not in my world they don't.

A rock that weighs the same as a feather would be known as a pebble, not a rock, so a feather will always fall slower than a rock even in a vacuum.

Now, if we were discussing pebbles and feathers.......

 

[Uklad]

Well I called the Dno at 4pm had a chat to a lovely lady about the high voltage with regard the pv setup and she amedietly said it sounds like you need it tapping... Anyway engineer turned up at 6:30 did some tests dispite his test was within range he took a look at my PVO logs and agreeded it needs to be looked at, so they are arranging a monitor to be put on my supply, watch this space

 

[moggy1968]

They do in a vacuum, plus terminal velocity of all items falling to earth not acted upon via other forces will be the same :tounge_smile:

Now lets get back to Ohms Law ...... lol

oh dear danesol, you completely missed the point!:banghead:

yes, they do in a vacuum, i.e. in the lab, but not in real life, thats why I said because of the presence of other factors. The same as in real life the voltage of your panels will not increase after may.

I know we have just had a long bank holiday but wakey wakey!!

 

[Earthstore]

One question to the OP where are you getting your voltage reading from?
Is it from the inverter or are you checking the incoming supply when the PV is not producing?

 

[moggy1968]

not in my world they don't.

A rock that weighs the same as a feather would be known as a pebble, not a rock, so a feather will always fall slower than a rock even in a vacuum.

Now, if we were discussing pebbles and feathers.......

so, if she weighs the same as a duck, she must be a witch!

 

[moggy1968]

One question to the OP where are you getting your voltage reading from?
Is it from the inverter or are you checking the incoming supply when the PV is not producing?

thats why I suggested he needs someone to look at the installation. It needs a proper evaluation on the ground.

 

[Earthstore]

long 2.5 maybe?

 

[Uklad]

Im getting my readings from the inverter but the engineer tested the incoming supply with the house disconnected and was getting 246v when he put the supply back on and the inverter started generating again it was measuring grid at 246.5v

03/04/13	19:20	10.457kWh	2.614kWh/kW	30W	66W	0.016kW/kW	23.5C	245.5V	-	-
03/04/13	19:10	10.446kWh	2.612kWh/kW	83W	24W	0.006kW/kW	24.0C	246.5V

 

[danesol]

Im getting my readings from the inverter but the engineer tested the incoming supply with the house disconnected and was getting 246v when he put the supply back on and the inverter started generating again it was measuring grid at 246.5v

03/04/13	19:20	10.457kWh	2.614kWh/kW	30W	66W	0.016kW/kW	23.5C	245.5V	-	-
03/04/13	19:10	10.446kWh	2.612kWh/kW	83W	24W	0.006kW/kW	24.0C	246.5V

IMO, this needs to be repeated at say peak generation time to see what the actual grid voltage is then... before reconnection

At least now you know its a fairly accurate reading, what you need to know now is why is goes up so high at certain times/generation periods - is it your kit and/or surrounding environment ?

 

[Uklad]

IMO, this needs to be repeated at say peak generation time to see what the actual grid voltage is then... before reconnection

At least now you know its a fairly accurate reading, what you need to know now is why is goes up so high at certain times/generation periods - is it your kit and/or surrounding environment ?

30/03/13

06:40

0.036kWh

0.009kWh/kW

137W

126W

0.032kW/kW

10.4C

250.5V

-

-

I think its environment sending it up to 250v and generation taking it to 253v im seeing a lot of voltage spikes with low generation

 

[moggy1968]

thats interesting, 246V is fine, but voltage spikes of 250 is going some. The previous advice of asking others in the area if they get problems with bulbs blowing a lot might be a good idea. I wouldn't make too much fuss to the DNO about your PV system as they may blame that and tell you to switch it off! are there a lot of other PV systems in the area (sorry if this has already been asked)

 

[Uklad]

thats interesting, 246V is fine, but voltage spikes of 250 is going some. The previous advice of asking others in the area if they get problems with bulbs blowing a lot might be a good idea. I wouldn't make too much fuss to the DNO about your PV system as they may blame that and tell you to switch it off! are there a lot of other PV systems in the area (sorry if this has already been asked)

Actually i noticed i local housing association has covered a full row of houses with panels i would estimate 25-30 kWh

 

[moggy1968]

ok, if thats on the same transformer that could push the voltage up

 

[Gavin A]

ok, if thats on the same transformer that could push the voltage up

no could about it.

 

[Earthstore]

Re your high voltage; What size is the AC cable to the inverter and what is the length of it from inverter to where it is connected to your supply?

 

[danesol]

Well in my experience and certainly as a "collective" you would be to contact your DNO and express a concern about high voltages and request them to come out to test and ultimately lower - naturally not mentioning you have Solar PV at this point, once you know your own house is in good order.

FYI - When they come out and test - they will take the raw tails anyway to discount any local issues to your internal wiring hence the above.............

 

[Uklad]

Re your high voltage; What size is the AC cable to the inverter and what is the length of it from inverter to where it is connected to your supply?

Sorry not been around for a while it looks like 2.5mm and about 5.5meter run

DNO are putting a Voltage recorder on for a week starting Monday.. i have started noticing voltage spikes even when im not at peak gen..

01/06/13	19:40	22.980kWh	5.745kWh/kW	353W	672W	0.168kW/kW	-	243.6V	-	-
01/06/13	19:30	22.868kWh	5.717kWh/kW	746W	498W	0.124kW/kW	-	250.0V	-	-

My system can not be doing this ?

 

[Uklad]

Update..

DNO put a voltage reader on for a week and reported back to me that line was within tolerance and they would investigate it further if anything can be done..

I did not hear anything for Months so written if off, out of the blue a get a phone call from an engineer at the DNO who was very knowledgeable about the subject and stated that PV is proving to be challenging in rural areas especially with the mix of domestic and commercial properties in close proximity, but he said he would look into the options for me..

A few days later he called back and told me they have tapped down the voltage at the primary substation for the area, not just my sub station and managed to knock off about 5 volts..

Good result i just have to wait until late spring now and see if the inverter cuts out..

 

[Worcester]

Thanks for updating us, and good to hear you've got a result.