PV output/generated energy

[Stu8975]

Hi all,
I'm after a bit of advice on whether or not my PV system is working correctly or not (mainly due to increased +50% usage over the last quarter according to my electricity bill compared to my highest pre PV bill).

Had a 2kw (I think) system installed for free by my local Housing group (Gentoo Sunderland) at the end of Sept '12. They get the benefit from the FIT tariff as it cost me nothing for the system.

System consists of 8x panels, Romag/Powerglaz SMT 6(60)P (up to 235watts), Aurora Power One PVI 2000 Outdoor UK inverter and Elster AS230 smart meter. Panels are south facing

I'm currently waiting for Gentoo to get back to me on higher than normal usage (may take a while), so thought i'd enquire whilst i wait.

Now i've never checked the readings/data before as the Inverter and meter are not easily accessible as they're in my loft.

According to the data the total energy produced is currently at 460kWh in just under 6 months. Does this sound normal/low? Can this be reset/affected by power cuts? (Theres been 3 since the install due to roadworks clowns).

If faulty could this cause higher than normal electricity usage?


Pre PV install I was using approx 4.5 units per day (I live alone and i'm not there half the time) and quarterly bills have all been sub 500 units usage since Ive lived there.

1st bill after PV install was for Sept/Oct/Nov and was down to 228 units, Oct/Nov assisted by PV. So i thought, great, my bills are gonna be virtually gone. Wrong!

Current bill is showing 755 units used this quarter (approx 8 units per day) and +262 units used over my highest pre PV bill of 498 units. Elec readings are all correct and not estimated.

So something has been eating my electricity and I think it may have something to do with the PV install.

So any help/advice/insight would be appreciated.

Stu

 

[moggy1968]

the problem you have there is with your electricity meter. It sounds like it is fitted with an anti tamper setting, so if someone reverse wired it it would still count the electricity consumption used. Unfortunately what this means is that when you are exporting to the grid it is counting that as you consuming electricity.
you need to contact your provider about changing the meter and getting your bill reassessed.

 

[Ian-LS]

Do you have a Siemens electricity suppliers meter as this is most likely the cause of your bills going up 50% as this meter has an anti-tamper measure on it which will add the PV generation exported to your imported electricity. If this is the case you should contact your elec supplier and ask to have this meter replaced ASAP with one that does not so this and have the money refunded to you to the sum of 50% of the PV generation as that is what is deemed to be your export rate.

 

[Stu8975]

Not sure on make, can't see 'Siemens' written on it anywhere. It is an old type dial meter though.

 

[balbecdaze]

We had one of those and it went backwards if we were generating! (Until they changed it boo!). You haven't been using an electric heater by any chance?

 

[moggy1968]

ok, it's not the meter, so there is something else going wrong.
I think you would need to get them back to have a look. the mystery is how your bills reduced, then went back up, very odd. Are you sure there is nothing left on that is consuming energy?

 

[nowty]

460 generated units in 6 months during the mostly winter months sounds about right for your system. Power cuts do stop the system generating but only for the time of the power cut.
That meter you have would not go forwards on exporting electricity, its only some of the modern digital ones which might give you a higher reading. In fact that meter might even go backwards on export which would be of benefit to you although if it does the electricity company would want to change it.
You say your first bill post PV which included 2 months of PV from Oct/Nov was 228 units down. That sounds about right, although that does suggest your meter might be going backwards on export as its difficult to self use a high percentage of the electricity generated.
For your second bill Dec/Jan/Feb your PV system will produce very little and you would likely only be down maybe 100 units or so. It’s the summer months which make a difference.
So are you sure its simply because your winter usage is higher with more lighting, or an incorrect meter read, or you have bought or using some new electrical appliance. Maybe occasionally using a portable electrical heater ?

 

[jason121]

Which meter has the 460kwh on it, the digital or the dial meter???

 

[Stu8975]

460 generated units in 6 months during the mostly winter months sounds about right for your system. Power cuts do stop the system generating but only for the time of the power cut.
That meter you have would not go forwards on exporting electricity, its only some of the modern digital ones which might give you a higher reading. In fact that meter might even go backwards on export which would be of benefit to you although if it does the electricity company would want to change it.
You say your first bill post PV which included 2 months of PV from Oct/Nov was 228 units down. That sounds about right, although that does suggest your meter might be going backwards on export as its difficult to self use a high percentage of the electricity generated.
For your second bill Dec/Jan/Feb your PV system will produce very little and you would likely only be down maybe 100 units or so. It’s the summer months which make a difference.
So are you sure its simply because your winter usage is higher with more lighting, or an incorrect meter read, or you have bought or using some new electrical appliance. Maybe occasionally using a portable electrical heater ?

First bill post PV was 228 units total used..resulted in a £33 bill for the quarter (approx 50% reduction on my normal bills), which is what i thought was a normal saving considering my low usage and with the aid of PV. Normal non PV aided usage works out approx £5.50 p/week, normal non PV bills have been between £62 (437 units) - £71 (493 units)max per quarter, with as of Dec '12 an annual consumption of 1580.80kWh. Current bill shows 1806.72kWh as of this time last year, so 226kWh up on last year. My tariff has slightly increased which accounts for a small increase on the bill, but doesn't explain the higher unit usage.

No electric heaters used, house has GF/GCH, no new electrical equipment since I moved in 18 months ago, other than the PV install.

Even if the PV generated 0kWh over the last quarter my usage still should of been similar to previous bills and not +262 units.

Ive spoken to my Energy supplier tonight who have agreed to change my meter, have to wait til mid April though and then wait another month and give them a reading from the new meter so they can check my usage before they can decide if they will discount/recalculate the bill.

Will get on gentoo's case tomorrow with regards them checking the install.

Stu

Oh..460kWh is on the inverter, think it was 458kWh on the smart meter.