#1 Dec. 5, 2013 15:17:00

SteveRogers
Registered: 2011-12-08
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Two year performance review


I put a graph in the gallery here:


http://www.microgen-database.org.uk/gallery/2-year-performance/pvgis-vs-anomoly





This compares my system's monthly production (expressed as a percentage of the PVGIS predictions) with the MET Office Sunshine Anomoly (% of 1981-2010 averages).  The red dots are my numbers and the blue dots/error bars the MET Office values, the error bars showing the range from the anomoly map legend.





Hopefully, it's clear what the graph means.  I think it's quite a good way of judging how a system is doing (and whether the PVGIS predictions are correctly done).


A lot of the points are in good agreement (within 5%) but you can see the first 5 months (Dec 11 to Apr 12) were a real problem when my installers used the wrong inverter.  Most of the other months are in good agreement, with a few exceptional performances compared with the MET office data.  My PVGIS predictions are possibly a few percent low.





I created the graph as a line plot in Excel.





Steve


P.S. I guess this might be gobbledygook to those who are not familiar with PVGIS or anomoly maps, in which case I suggest that you search the forum for discussions on these topics (and become a PV geek like me ).





Edited SteveRogers (Dec. 5, 2013 15:17:00)

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#2 Dec. 6, 2013 11:05:00

gary.caldwell@ncl.ac.uk
Registered: 2012-08-22
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Two year performance review


This is very interesting, although I can only find data normalised to country rather than region. I've tried to cross ref your data to the country data but couldn't match it up. Were you able to find a more geographically defined data set?





Edited gary.caldwell@ncl.ac.uk (Dec. 6, 2013 11:05:00)

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#3 Dec. 6, 2013 15:55:00

SteveRogers
Registered: 2011-12-08
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Two year performance review


I assume you mean the MET Office data, Gary.  I've estimated my position on the map after choosing the appropriate boxes (i.e. sunshine, year, month and 1981-2010 anomoly):


http://www.metoffice.gov.uk/climate/uk/summaries/anomacts


The map shows the % for the chosen month compared with the 1981-2010 average.





I think they moved the web address of these maps a few months back and maybe you are looking at the previous page.





Does that help?


Steve


3.96 kWp system, S facing, N York Moors








Edited SteveRogers (Dec. 6, 2013 15:55:00)

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#4 Dec. 20, 2013 01:40:00

SunshineCoaster
Registered: 2012-02-23
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Two year performance review


Any period with a wrong inverter would certainly show a difference. You seem to have lost about half the output you would have expected over a 5 month period. I don't suppose many installers accept liability and offer compensation for your reduced FiT income due to this?
That period was above PVGIS for us as you will see from my chart. Our generation was also low in the early months after installation, though no system changes were needed as there was simply below average irradiation for the 4 months Nov 2010 to Feb 2011, being at or below PVGIS levels - and each has since remained as record lows so far for their respective months. That period was then immediately followed by 4 good months from March to June 2011, significantly above PVGIS levels - and each one of those has since remained record highs so far for their respective months!
Following those “anomalies,” generation only fell below PVGIS levels in Feb and Mar of this year.
Overall I'm happy to be averaging about 17% above a PVGIS that was based on 19% overall system losses.
The uploaded chart at http://www.microgen-database.org.uk/gallery/3-year-performance shows our PVGIS and year-on-year monthly generation covering the past 3 years for you to compare.








Edited SunshineCoaster (Dec. 20, 2013 01:40:00)

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