PV Solar & High Electric Bill

EssJayEff

Hello Redspider.

I too live in Gloucestershire and had a 22 panel (3.96 kw peak) system installed about a week after yours. So far we have generated 585 kwh which is better than both my installer thought reasonable and what I got from the re.jrc.ec.europa.eu website, linked somewhere on this (MSE) site. I hope it lasts.

You don't say what output the panels are - without this we can't say whether it is reasonable or not. It would also be good to know what inverter they fitted.

A second point to note is that unless you have a moveable roof the optimum angle is for summer - not for now. Nevertheless, you should be doing a lot better than you are if it is 3.96 peak.

Some figures you might find helpful when talking to your supplier are below. Rows are Jan to Dec. The first column is that predicted from the website above for my location (near Gloucester). The second column is calculated from actual figures supplied from a London installation and published somewhere else on this site, which I then proportioned to what I was told I might expect (3358 kwh per annum). As you can see they are pretty similar - sometimes exactly the same. Third column is generation to date.

108 121
167 175
263 261
370 370
424 427
409 407
433 433
388 402
310 305
211 226 275
127 139 143
80 86 53 to date (12th)

I don't know about the electricity meter but I would get one of those current measuring devices. As you have PV it will be compromised as regards accumulation figures but it will allow you to see on demand usage in the evening and wil be helpfull during the day so long as you realise it doesn't know which direction the current is flowing.

RedSpider

Hi EssJayEff

Thank you for that ...nice to be able to speak with someone local to get some comparisons.

As you may have quessed i have been a bit naive about monitoring my electric and what the solar panels have generated and i should have been on the ball along time ago...so it seems.

However, i have taken past readings..not daily admittedly but i have calculated the following:

NOTE Panels were installed on 9th Sept and in october we cut down (sshhhhhhhhhh....) a tree that was clearly shading some of the panels:

Sep - 111
Oct - 168
Nov - 77
Dec - 21 (To Date)

So, going on your figures we seem to be way short of what we should be generating.

smartn

I'm in Bristol with a 2.11 kWp system. Only recently installed but in November we generated 68 units (partial month, only started on 6th Nov) and so far in December we have generated 44 units. Can you confirm what kWp your system is?

RedSpider

Not very good at this but this is the info i have on my certificate:

Estimated Annual generation: 3539 kw

I have a copy of the system Variant report that they gave me dated 03.09.10 and this is what it says:

PV Output: 4.07kWp
Gross/Active PV surface Area: 28.53 / 28.45 m2
PV Array Irradication: 31,865 kWh
Energy Produced by PV Array (AC): 3,538.1 kWh
Grid Feed-in: 3,539.1 kWh

system Efficiency: 1.1%
Performance ratio: 77.3%
Inverter Efficiency: 93.8%
PV Array Efficiency: 11.8%
Specific Annual Yield: 865.7 kWh/kWp
co2 Emmisions Avoided: 3,122 kg/a

We have 22 x 185 Panels

mysterons

I've a 3.96kwp system that's produced 330kwh in 2 months. I live on 'the drier side of the uk' Given that Gloucestershire is prone to more wet weather than the eastern counties I dont think your results at 374kwh are that far out.
I also have a large family living at home and have seen usage of 6000kw plus per winter quarter in the past hence why i got interested in having PV. It would be easy to have a previously estimated reading rack up your current bill.
Did you pay for your PV install or is it one of the rent a roof systems? I ask because your system exceeds the 4.0kwp limit for the top rate of FIT's. Systems are guaged by the 'Total Installed Capacity' not by inverter output or the lower 'Declared Net Capacity' figure. Do you have a FIT contract with a supplier? What rate are they paying?

EssJayEff

Hi again RedSpider,

I think you need to ask your supplier why they installed a system that takes you out of the max bracket (4kw) for negligible gain (0.07 kwp). By doing so they reduced your potential income from 41.3 to 36.1 per kwh produced - about 14%. That will literally cost you thousands over the 25 years. You would be better off removing one of the panels - your electricity would be a bit less but your additional income would more than make up for it.

I'm also convinced that if you do have the optimum angle for annual generation then there is something wrong. Google 'sunnyportal' and you can get access to about 100 generation figures for UK installations. Based on what you've done to date there is no way you will generate what they said you would.

reeac

RedSpider: using your list of lights, computer, TV, boiler etc. I guessed that it came to about 1 kW maximum and so 1 kWh. rather than the 2.7 kWh. that your meter read for 1 hour of running. That, plus the extraordinary 8800 kWh that you used in 3 months [which is 10 times what we use] makes me wonder seriously about your meter - either the actual meter or maybe the way it's connected up.

Mankysteve

RedSpider wrote: »

The reading on my Inverter shows that we have accumalted 374 units since it was installed 3 months ago. Surely this can't be right?

You do have two meter right? One use and one generation. You can use the Inverters reading to get FIts its a proper Ofgem installed meter.

Your fitter has estimated that you'll do 875kwh a year so its output at the moh is not that bad at

As for your usage there something not quite right there from what you claim your running.

I wonder if you haven't got a separate generation meter and the feed in from the inverter is upsetting your normal meter.

EssJayEff

Mankysteve wrote: »

Your fitter has estimated that you'll do 875kwh a year so its output at the moh is not that bad at

RedSpider.

Your fitter has estimated a specific annual yield of 865.7 KwH/kwP. This is NOT the same as annual generation. It is the estimated annual generation divided by the kwp for the system. KwP is the maximum you can expect to get from it when everything is optimum. In other words your fitter has not said you can expect 865.7 for the year - he has said you can expect about 4.07 times that - ie. over 3500 kwH per annum. Specific annual yield also takes into a/c the electricity used from the grid in keeping the system on standby which is minimal but accounts for why the calc above doesn't work out exactly.

Based on your figures to date, my figures to date, and every other installation in the south of the UK for which actual figures and estimates are available, something is seriously wrong with your generation figures if you have a good unshaded south facing roof.

Good luck sorting it out.

dfurn

Did Redspider ever let us know what was causing his high electric bill?