20 Mwh Club

[dan_b]

Nice, always like a good meter-roll-over pic, like when your car clocks over a milestone like 100,000 or something.

[marshman]

It will soon be time to "upgrade" the thread title and get a constitutional change to the name of the club as more of us cog up to 30 MWh (and higher).

With the last few weeks of sunny weather my 3.15 kW pk Sharp system has just clocked up 30 MWh (installed April 2010). Being an early adopter it cost a lot but it still repaid the outlay sometime time ago.

Also took the opportunity to wash the panels down. We haven't had rain for many weeks and I was getting concerned at the amount of bird poo and dust covering the panels. They are at a very shallow angle so even when it does rain they take a while to clean themselves. Made a difference of about 200W to the output (just under 10% at the time) so worth doing.

[brackwell]

I had my panels washed back along but any difference i saw i put down to the cooling of the panels. I really dont know how you would measure any of this.
Ken

[marshman]

Hi Ken,

Generally I would agree Ken but they really were dusty/dirty - never seen them so bad. I cleaned them around 3pm. When I started the inverter was showing a fairly steady 2250W. When I had finished (approx 30 mins later) the reading was around 2450W and stayed higher long after any temporary cooling effect.  (clear skies, not a cloud in sight). The daily readings for the last 2 days have been higher than other recent "perfect days" in spite of the much higher  ambient temps. There were a lot of "splodges" of poop on them which must have affected output.  My panels are on a garage roof so very easy to get out and as I said they are at a shallow angle so can suffer dust and dirt settling on them in the dry summer months. I do generally rinse them off once a year to stop any lichen getting a foot hold.

I have "played" with cooling before and its not worth the effort, tried ducting cooling air under the panels and trickling cold water over them. Any effect is at best temporary - and anything that goes on in front of the panel - i.e. trickling water just cuts down the amount of light and hence light counter acting any benefit.

Roger

[brackwell]

Hi Roger,
I can see the benefit in your case due to the flat roof etc.  I think solar panels are made with "self leaning glass" which must help at larger angles.  Despite the long sunny dry days i have been having quite heavy dews which i guess may help at large angles even if the dirt just drifts down to the lower edge frame.

Ken

[JohnS]

It will soon be time to "upgrade" the thread title and get a constitutional change to the name of the club as more of us cog up to 30 MWh (and higher).

No.  By all means change it to "Big systems club".

But some of us with more modest roofs and systems are still waiting to hit the magical 20Mwhs.  I will be clocking up 16Mwhs this week and don't want the goal posts moved before getting to 20Mwhs
hopefully in late 2020.

[marshman]

It will soon be time to "upgrade" the thread title and get a constitutional change to the name of the club as more of us cog up to 30 MWh (and higher).

No.  By all means change it to "Big systems club".

But some of us with more modest roofs and systems are still waiting to hit the magical 20Mwhs.  I will be clocking up 16Mwhs this week and don't want the goal posts moved before getting to 20Mwhs
hopefully in late 2020.

Sorry John, 'twas a bit thoughtless of me  .  Perhaps we should move away from an absolute number and quote as a "per kWpk installed figure".  So for my 3.15kW system I have been a bit premature as I am only on 9.5MWh/kWpk - no celebrations until I hit 10 

[JohnS]

Roger,

No problems.  I am only on 7.6MWh/kWpk.  I guess that reflects a bit of shading on mine and your sunny coastal location.

Have you noticed any loss of performance over time?  My trendline of sunshine hours per year is flat and my trendline of Kwh per sunshine hour per KwP has declined from about 0.608 to about 0.588 over 8 years which I reckon is about 0.4% per annum.  Sunshine hours are as per the  Met Office at Heathrow.  I appreciate that there are all sorts of arguments about guality of sunshine, morning or afternoon bias for non due south systems etc, but after 8 years there must be some statistical significance.

John

[marshman]

Roger,

No problems.  I am only on 7.6MWh/kWpk.  I guess that reflects a bit of shading on mine and your sunny coastal location.

Have you noticed any loss of performance over time?  My trendline of sunshine hours per year is flat and my trendline of Kwh per sunshine hour per KwP has declined from about 0.608 to about 0.588 over 8 years which I reckon is about 0.4% per annum.  Sunshine hours are as per the  Met Office at Heathrow.  I appreciate that there are all sorts of arguments about guality of sunshine, morning or afternoon bias for non due south systems etc, but after 8 years there must be some statistical significance.

John

Not noticed any drop off at all. Still hitting 24kWh on the best days and inverter power topping out at 3050W  (it is a SB3000). Just had 2nd best ever month in June and well over 320kWh already in July. Never done a check against sunshine hours as there are no local stations. Annual figures are fairly constant on both of my systems.

        Sharp      Suntech
        3.15kW      3.67kW
2011   3662   
2012   3635     4009
2013   3468     3838        ;issues with grid supply volts causing inverter disconnect
2014   3419     4012        ;issues with grid supply volts causing inverter disconnect
2015   3560     4014
2016   3660     3998
2017   3623     3984 kWh

Are panels getting dirty?

Roger


Edit: to correct units on inverter power!  3050W and not 3050kW 

[TheFairway]

Also took the opportunity to wash the panels down. We haven't had rain for many weeks and I was getting concerned at the amount of bird poo and dust covering the panels. They are at a very shallow angle so even when it does rain they take a while to clean themselves. Made a difference of about 200W to the output (just under 10% at the time) so worth doing.

I took a hose to our lower panels today - the runoff then went into help top up the water butts. The panels were in the shade, it was end of the day, but the improvement was noticeable and unequivocal.  

Ok, increase in f-all is still f-all, but an indicator that cleaning the dust off in this weather makes a difference. Probably less so when its full sun though.

Upturn in tail of green line since cleaning panel. No other change in conditons other than approx 5% of panel area 'dusted'. It was well past 7pm and panels were already cool.

[supremetwo]

I took a hose to our lower panels today - the runoff then went into help top up the water butts. The panels were in the shade, it was end of the day, but the improvement was noticeable and unequivocal.

After the combine's work in the field opposite this evening, my panels, cars and local area are covered in a fine layer of threshed straw.

Fortunately no hosepipe ban here at the moment.

[marshman]

Just noticed that my system has just passed the 10MWh/kWpk mark.  (2 days ago). 8 yrs 214 days after install.

Will start a new thread as suggested by JohnS earlier in this thread

[Philip R]

Yesterday, My 14 panel, 3.5kW PV system passed through the 20,000 kWh barrier. after just over 6 years on the roof.
Over the last three days including today, the system has produced over 46kWh, due to the sunshine and moderate temperatures.
 
 




Philip R

[supremetwo]

30 MWh on 3/2/2019 at 10:44 AM

Corrected from 2/3 - did not notice USA date format in database.

[Philip R]

Supemetwo,
Is that a prediction or can you foresee the future? BTW well done.