Solar panels - low output over the last 3 months

[Oliver Par]

Really just a very basic question. I hadn't been checking on my panels/generation meter for a while as life had just been very busy, but I was quite taken back when I did my generation meter reading?! In the last 3 months it put out less than half of what it did in the first two months (approx same time last year)?! Do I need to be concerned and if yes, where or what should I start checking? Anybody experienced similar or what the weather really that bad?

Thanks,
Oli

 

[danesol]

Mine are up !!

Have you washed them lately ??

Have you checked your inverter panel for any obvious ??

 

[mdovey]

Mine are down: 123kWh for Jan/Feb compared to 154kWh for Jan/Feb last year (2kW system). That may be a mixture of weather, dirt and panel degradation.

However that does sound a dramatic drop.

 

[SRE]

Are you comparing it with Feb & the whole of March last year - March was phenomenal - we reached mid 20's on several days and had hardly any rain. We're in the North and our panels did 30kwh Nov, 31kwh Dec, 43kwh Jan and 191 in Feb - all completely normal for the time of year.

 

[Vegelen]

As usual with the British weather it is doing a fine job of keeping us guessing.....

 

[danesol]

Mine are down: 123kWh for Jan/Feb compared to 154kWh for Jan/Feb last year (2kW system). That may be a mixture of weather, dirt and panel degradation.

However that does sound a dramatic drop.

Our Jan was down 15%, but Feb was up by 26% ( compared with 2012 ) and March looking as good as last year so far..........

 

[FB.]

.
For me, mid-Jan 2013 to mid-March 2013 is 13% lower than the same period last year.

Here in Cambs we tend to have a lot of cloud in late winter and early spring but we tend to have unusually sunny autumns; September 2012 wasn't much less than May, June, July or August 2012, and was notably more than April 2012.
Met office historical weather trends suggests that I should expect sunnier autumns than most parts of the UK:

Met Office: UK mapped climate averages

-

 

[FB.]

On a slight tangent, today was the first day in 2013 that I'd noticed my system getting anywhere near full output (about 90% of maximum today).
Mid-morning, it was peaking around 3.3kW output from the inverter (3.75kWp panels as per signature).
Weather conditions were sunny spells mixed with white cloud, temperature around 2'C, with a brisk North wind.

 

[pwboston]

Yes last 2 days ive been peaking at just under 3.6kw.

 

[MicraShed]

2.5kWp system in Preston did from the beginning of Nov 2012 to Feb 2013 just 112kWh being generated, what wasnt used in house was siphoned off into the immersion. However from Feb 3rd to March 3rd it kicked out 105kWh and its done 25kWh since Sunday, so happy days are here again and I have a tank of piping hot water!

 

[newtonflotman]

My system 6xSanyo 240HIT plus Sma1200 Invertor has given me a 40% reduction Dec-Feb compared to last year. Last few weeks though it has been producing far better. Think Sunny East Anglia has missed out on the sun in the winter months this year. Checked on PVOutput for local systems and they have been pulling in similar.

 

[FB.]

Think Sunny East Anglia has missed out on the sun in the winter months this year.

Yes, since late October it felt unusually sunless compared to what we're used to. My wife recently commented how yellow the grass looked, probably because we've had almost no sun.

January was particularly bad, without any days having dawn-to-dusk sunshine and many days with black cloud just hanging there.

January had 21 days below 2kWh of generation where I should have been generating an average of 3-3.5kWh per day (about 2.5kWh on an average day at the start of the month and 4kWh on an average day at the end of the month). A couple of 6's early in the month, an 8 in the middle of the month and three 7's and 8's at the end of the month helped put a little lipstick on the pig.

 

[puddy]

I had a couple of very bad days in Feb with Fog and the panels were coated with snow also had Frost covering the panels completely for at least 5 days in total not going over at least 1.2kw per day. Yet 4 days going over 10kw



4/2/13 10.7kw
17/2/13 12.5kw
19/2/13 11.9 kw
28/2/13 11.2kw

2.5kw system 12 panels with Fronius Inverter in South Lincolnshire

Jan 2012 113 kWp Jan 2013 85 kWp
Feb 2012 140 kWp Feb 2013 134 kWp
Mar 2012 289 kWp Mar 2013 134 62 kWp 12/03/13

 

[langstroth2]

where or what should I start checking?

As suggested , first thing I'd do is confirm whether you have a problem at all - are there any nearby systems you can compare with, say on the likes of pvoutput.org etc? Jan and Feb have been poor months for me - even had a few days of no generation due to snow cover. Output abut 20% down on last year in Feb.

 

[liquidity]

My Jan and Feb outputs were down 35% and 15% respectively on the same months in 2012.