Our solar production

[DuncanCunningham]

I'm too lazy to get those kind of stats.. I'll just take mine from the APSystems webpage I can login to. October could of been better as a Micro-Inverter had issues and it took weeks to get a RMA figured out. Most of that wasn't down to APsystems. Once the process was followed they matched the support promised. I was down two 325Watt panels for over a month.

[davewill]

Well, I hadn't checked on my production for a while, so I did. Low and behold, the much of the last year is showing a significant decline, especially Nov, and Dec isn't looking any better despite unseasonably warm and sunny weather in SoCal this fall. Just as telling the peak numbers are lower, too.

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         2017        2016
Jan     787.68     846.75
Feb     827.43   1,260.48
Mar   1,420.07   1,364.66
Apr   1,569.70   1,421.10
May   1,343.54   1,234.13
Jun   1,473.96   1,486.90
Jul   1,516.38   1,620.35
Aug   1,340.45   1,476.57
Sep   1,156.03   1,234.49
Oct   1,129.70   1,111.95
Nov     787.77     992.07
Dec     324.97     749.82


Plus the system has been showing a steady year by year decline, then a steeper one this year (we aren't going to make enough between now and the end of the year to make this look tons better.

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Energy Table
2012    6,132.38   
2013   15,442.73
2014   15,280.89
2015   14,966.99
2016   14,799.27
2017   13,675.74

I'm on a lease, so I called Sunpower. They agreed there is something up and will be sending out a technician. Should all be on their dime.

[RegGuheert]

Plus the system has been showing a steady year by year decline, then a steeper one this year (we aren't going to make enough between now and the end of the year to make this look tons better.

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Energy Table
2012    6,132.38   
2013   15,442.73
2014   15,280.89
2015   14,966.99
2016   14,799.27
2017   13,675.74

I'm on a lease, so I called Sunpower. They agreed there is something up and will be sending out a technician. Should all be on their dime.

Wow! You've lost about 9% of your production in four years. (I used 14.1 MWh for this year.) That's better than a Nissan LEAF battery, but not a whole lot better.

I wonder if Tony Williams would share his annual numbers to give a trend for comparison.

[NeilBlanchard]

Well, I hadn't checked on my production for a while, so I did. Low and behold, the much of the last year is showing a significant decline, especially Nov, and Dec isn't looking any better despite unseasonably warm and sunny weather in SoCal this fall. Just as telling the peak numbers are lower, too.

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         2017        2016
Jan     787.68     846.75
Feb     827.43   1,260.48
Mar   1,420.07   1,364.66
Apr   1,569.70   1,421.10
May   1,343.54   1,234.13
Jun   1,473.96   1,486.90
Jul   1,516.38   1,620.35
Aug   1,340.45   1,476.57
Sep   1,156.03   1,234.49
Oct   1,129.70   1,111.95
Nov     787.77     992.07
Dec     324.97     749.82


Plus the system has been showing a steady year by year decline, then a steeper one this year (we aren't going to make enough between now and the end of the year to make this look tons better.

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Energy Table
2012    6,132.38   
2013   15,442.73
2014   15,280.89
2015   14,966.99
2016   14,799.27
2017   13,675.74

I'm on a lease, so I called Sunpower. They agreed there is something up and will be sending out a technician. Should all be on their dime.

Are trees growing taller, and shading your system more over time?

[dgpcolorado]

One thing that I do see very clearly from day-to-day is that I get better production in colder temperatures, other things being equal. Is it possible that generally warmer weather this year, and in recent years, is causing a drop in production?

I was told when I got my panels that production would drop over the first two years and then decline only gradually for the next twenty or so. I get a lot more "weather" here than there is in San Diego, so my production fluctuates somewhat; any significant production drop seems lost in the weather noise:

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              Old panels       New panels
2009             1165 kWh
2010             1132
2011             1203
2012             1227
2013             1179             2148
2014             1145             2072
2015             1125             2034
2016             1150             2077
2017             1109             1988 (as of Dec 11)


Solar panels on 6 January of this year. Mostly sunny, unseasonably warm, and dry so far this fall.

[GRA]

One thing that I do see very clearly from day-to-day is that I get better production in colder temperatures, other things being equal. Is it possible that generally warmer weather this year, and in recent years, is causing a drop in production?

Production will always be better in colder temps, as the voltage will sag with higher temps (modules typically run 20-25C higher than ambient), so it's possible. Cleaning or lack of same is also an issue, but another factor could be gradual scratching of the glass surfaces of the modules due to blowing sand etc. With the exception of cleaning it's not worth worrying about, assuming you've made no changes since you installed it, as there's not much you can do about it. Anyway, here's a decent primer on the factors involved: https://www.civicsolar.com/support/installer/articles/how-solar-panel-temperature-affects-efficiency

As your array is stand-alone rather than roof mounted, restricted air circulation shouldn't be a problem for you.

[RegGuheert]

Is it possible that generally warmer weather this year, and in recent years, is causing a drop in production?

Nope, with a temperature coefficient of power of -0.3%/K, the average temperature of San Diego, CA, would have had to have risen by over 54 degrees Fahrenheit to account for a 9.1% drop in production. In fact, there was no real change in temperatures between 2013 and 2017:

[davewill]

Are trees growing taller, and shading your system more over time?

Nope, clear air over and around of my house. As far at temperature, not enough difference to explain things. Mainly I was noting that we've had not a drop of rain and no cloudy days this fall.

Before I thought it was dirt and I'd have to clean them at some point, but the last year's drop seems a little big for that.

[RegGuheert]

Due to the pointing angle of the M250s on the roof, I don't expect to see the full 12.775 kW at any time this winter, but I do think we might see over 12.5 kW, particularly on a cold, clear day when there is snow on the ground (and none on the arrays).

Sure enough, January 30 saw a new momentary production peak, so I thought this would be a good time to update our system's production through January.

As I mentioned in my previous post, the AC rating of the array now stands at 12.775 kW. The DC rating is very similar at 12.75 kWp. On January 30, 2018, at 35 minutes past noon, production peaked at 12.6 kW (more precisely: 12.567 kW):



2017 turned out to be the lowest production year since the array was expanded to include 54 inverters. Production came in at only 17,716 kWh. That is 839 kWh less production than the record set the previous year.

The good news is that January 2018 set a new January production record for this system, edging out January 2016 by a mere 600 Wh. We'll call it a tie! But I will note that this year's January record would NOT have occurred without the new 250W inverters attached to the PV modules in the field array. That boosted the production of those PV modules last month by about 10% versus the old 199W inverters.

Below are all our numbers for 2011, 2012, 2013, 2014, 2015, 2016, 2017, and 2018 along with the PVWatts predictions for the old array (PVW42: good through June 2014) and the new array (PVW54: good starting with July 2014):

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Month    PVW42   2011   2012   2013   2014   2015   2016   2017   2018  PVW54  Units
------------------------------------------------------------------------------------
January    916    669    869    822    857   1006   1300    756   1300   1229   kWh
February   702    158   1085    866   1054   1361   1192   1241           915   kWh
March      965      0   1350   1152   1113   1547   1498   1572          1240   kWh
April     1465      0   1465   1495   1338   1737   1754   1654          1899   kWh
May       1583      0   1477   1491   1457   2069   1574   1618          2074   kWh
June      1268      0   1478   1368   1521   1585   1932   1916          1666   kWh

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July      1448    595   1395   1406   1880   1823   1887   1792          1902   kWh
August    1442   1347   1447   1333   1794   1887   1932   1778          1875   kWh
September 1209    910   1295   1414   1577   1495   1551   1612          1555   kWh
October   1304    931    981   1034   1258   1415   1593   1587          1713   kWh
November   864    949   1041   1018   1227   1277   1340   1205          1154   kWh
December   820    803    612    669    812    865   1002    985          1108   kWh
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Totals   13986   6362  14495  14068  15888  18067  18555  17716   1300  18330   kWh    Total: 106.451 MWh

Our system has produced 106.451 MWh from installation through the end of January 2018.