Anyone with good cleaning tips?

[bando]

Bando,

Have you using the "report" feature on Locus monitoring? Click on "reports", then "Generated vs. Expected". You'll get this screen.

yes i have occasionally. i actually asked the Project mgr about this report when we turned on our system because the total annual "expected" per Locus says 17,011 and is different from the initial proposal's 18,200 annual kwh. he said Locus automatically uses various calculations about the system size and orientation and location to calculate, however, it's not the same as their metric on the proposal and to not pay too much attention to either since they are both typically much lower than what customers will see.

For Dec 2013, expected was 943. Actual was 1256.

For Jan 2014, expected is 1027. Actual thru right NOW is 910, with 12 more full days to go this month.


i would not be surprised to break 20,000 by the one year anniversary (assuming we can keep them relatively clean and get some much needed rain)

[silversaver]

yes i have occasionally. i actually asked the Project mgr about this report when we turned on our system because the total annual "expected" per Locus says 17,011 and is different from the initial proposal's 18,200 annual kwh. he said Locus automatically uses various calculations about the system size and orientation and location to calculate, however, it's not the same as their metric on the proposal and to not pay too much attention to either since they are both typically much lower than what customers will see.

For Dec 2013, expected was 943. Actual was 1256.

For Jan 2014, expected is 1027. Actual thru right NOW is 910, with 12 more full days to go this month.


i would not be surprised to break 20,000 by the one year anniversary (assuming we can keep them relatively clean and get some much needed rain)

Must be real ncie to see that kind of production South facing arrays rocks!!!

[bcroe]

Dec Production

For Dec 2013, expected was 943. Actual was 1256.

That shows the sun benefit of southern Cal. With all the storms & clouds, managed
1270 in NW IL in Dec, but a lot more panels. But, I guess that is the plan. Bruce Roe

[silversaver]

yes i have occasionally. i actually asked the Project mgr about this report when we turned on our system because the total annual "expected" per Locus says 17,011 and is different from the initial proposal's 18,200 annual kwh. he said Locus automatically uses various calculations about the system size and orientation and location to calculate, however, it's not the same as their metric on the proposal and to not pay too much attention to either since they are both typically much lower than what customers will see.

For Dec 2013, expected was 943. Actual was 1256.

For Jan 2014, expected is 1027. Actual thru right NOW is 910, with 12 more full days to go this month.


i would not be surprised to break 20,000 by the one year anniversary (assuming we can keep them relatively clean and get some much needed rain)

The expected value were exat same number from CSI calculater

http://www.csi-epbb.com/default.aspx

Screenshot_2014-01-20-23-09-53.jpgScreenshot_2014-01-18-19-35-37.jpg

[russ]

The expected value were exat same number from CSI calculater

http://www.csi-epbb.com/default.aspx

[ATTACH=CONFIG]3612[/ATTACH][ATTACH=CONFIG]3613[/ATTACH]

Wonderful how sales people play with data and words! CSI has a different purpose and is far more accurate.

[silversaver]

Wonderful how sales people play with data and words! CSI has a different purpose and is far more accurate.

Sorry, what is your point?

[J.P.M.]

The expected value were exat same number from CSI calculater

http://www.csi-epbb.com/default.aspx

[ATTACH=CONFIG]3612[/ATTACH][ATTACH=CONFIG]3613[/ATTACH]

Without putting words on Russ' keyboard (or mouth if he uses speech recognition), The CSI estimate is just that - an estimate, not a prediction. It is a sizing tool. No more. Actual weather for every hour, day, and year that the model uses and which controls how the array will perform will be different than the actual weather conditions that array is exposed to. Models like PV Watts and others used for sizing often use one of two "Typical Meteorological Year" data sets which are designed to be representative of "average" weather, by combining 12 months - each month being the most "typical" by some reasonably logical criteria, giving some extra attention to the solar irradiance.

It's probably good as used for performance estimates for sizing, but about as useless for predicting future short term array performance month to month as long range weather forecasts are for planning vacations. Over many years a well designed system sized using TMY data may well produce the expected output - short term useless.

The idea that the "expected" values on the graphs seem to be copied from PV Watts is something I would call misleading - and perhaps lead the ignorant to infer some incorrect and misleadingly wrong conclusions without some clarification, which clarification as it appears to me, seems to be missing.

The CSI data is no more than a dart throw of long term performance. To predict what a system will do in any short term based on the TMY data is a misapplication of that data. Caveat Emptor.

[russ]

PV Watts is based on 20 year averages - more than likely it will never be correct at any given time.

[J.P.M.]

That shows the sun benefit of southern Cal. With all the storms & clouds, managed
1270 in NW IL in Dec, but a lot more panels. But, I guess that is the plan. Bruce Roe

I'd respectfully suggest Bando's data may show how vendors underpredict performance more than so. CA has a lot of sun. - we do, but I'd suggest that Dec. at my house, while good, was not that far off "average" - whatever that means. the 2d half being somewhat "sunnier" than the 1st half.

My system's output for Dec., 2013 was 590 kWhrs. SAM output for the same period using TMY data was 582 kWhrs. I've got other stuff dealing with something called "clearness indices" that show about the same thing.

Comparing:

Bando Dec. = 1256 kWhrs.
J.P.M. Dec. = 590 kWhrs.

Bando/J.P.M. = 2.13

Bando Jan., mo.to.date = 910 kWhrs.
J.P.M. " " " " = 433 kWhrs.

Bando/J.P.M = 910/433 = 2.10

Bando system size = 11760 W
J.P.M. system size = 5232 W

Bando/J.P.M. = 11760/5232 = 2.25

Bando's bigger, but with different orientation and equipment. See my prior post on this thread.

I don't want to get too many irons in the fire here, or put too fine a point on it. But, to me it looks like based on recent, consecutive, nearly identical clear day measured output comparison between Bando and J.P.M. further back on this thread, the above data and SAM estimates for my system, that Bando's estimate from some vendor of 943 for Dec. was a bit low and may perhaps have been better represented by something like 1200-1250 kWhrs.

As a yearly "estimate" - SAM's estimate for my (J.P.M.) system is about 9479 kWhrs./yr. That seems high, but it's for a new system (with 1% soiling, more on that later), pretty good orientation and not too much shade. It also seems to match system output when compared to many hourly data I've taken over the last 3 months when adjusted for actual vs. TMY weather and irradiance data.

Anyway, if Bando's output really is about 2.1 times J.P.M. output, as seems possible given the above, then perhaps long term, reasonably clean, trouble free output might be something like 2.1 X 9479 =~~ 19,900 kWhrs./yr.
If someone predicted 18,200 kWhrs./yr., that estimate doesn't seem too far off - about 8 or 9% low. But still low.

At the end of the day, this is all a crap shoot anyway. The reality may very well be something like output can be guessed +/- 20% half the time on a good day, maybe. It just seems to me that many people believe the stuff that vendors often spew and get oversized systems from vendors who underpredict performance - one result being a happy customer who thinks they got more than they paid for because performance exceeds a overly conservative estimate when actually they may have paid too much for a system that is not as cost effective as it might otherwise be if properly sized.

I might still get an oversized system, and that's my choice. But I'd suggest I'd be better making that choice on data that better predicts probable, long term performance than some dour overly conservative estimate from someone with skin in the game. No one I know of ever got fired for selling too much. And, sort of analogous to the movie business which is in the end all about putting asses in seats, vendors make money putting equipment on roofs - not saving customers money per se.

Caveat emptor.

[russ]

Very localized conditions can really change things - ask Mike the moderator about his farm location and early morning fog.

[J.P.M.]

Very localized conditions can really change things - ask Mike the moderator about his farm location and early morning fog.

I appreciate what you are writing, perhaps more than most. I also appreciate the limitations of the paucity of data I'm hanging my hat on, but I do find it interesting. I'm a bit surprised, but only a bit, that the data from 2 systems with different equipment and orientation probably 20 miles apart, seem as consistent as they are. Still, caution that this is all little more than anecdotal, at least at this time is probably appropriate.

[SoCalsolar]

Flashing back to the original thread purpose

Interesting discussion both on the cleaning and the performance of various equipment.

I posted this a while back and may not be applicable do to our lack of rain but is a study done by Google
about their solar arrays and their cleaning experience. I've been MIA for a while. JPM did you ever buy panels?

http://googleblog.blogspot.com/2009/07/should-you-spring-clean-your-solar.html

[J.P.M.]

Interesting discussion both on the cleaning and the performance of various equipment.

I posted this a while back and may not be applicable do to our lack of rain but is a study done by Google
about their solar arrays and their cleaning experience. I've been MIA for a while. JPM did you ever buy panels?

http://googleblog.blogspot.com/2009/...our-solar.html

Welcome back. Hope all's well. The short answer is yes. More to follow shortly.

[bando]

Interesting discussion both on the cleaning and the performance of various equipment.

I posted this a while back and may not be applicable do to our lack of rain but is a study done by Google
about their solar arrays and their cleaning experience. I've been MIA for a while. JPM did you ever buy panels?

http://googleblog.blogspot.com/2009/...our-solar.html

i would be very interested in seeing the results of your study! i requested access to the slideshow...

your photo also shows exactly what is happening on mine, however on mine the caked-on dirt is a straight line covering the bottom 5-6" of the panels, not just the corners. the caked on dirt just looks terrible. it has been WEEKS here without any drop of rain, and the panels are pretty dusty again. we are planning some spring cleaning ourselves with some pressure washing and window cleaning and will probably have them do the panels just for our own research's sake this time.

[J.P.M.]

i would be very interested in seeing the results of your study! i requested access to the slideshow...

your photo also shows exactly what is happening on mine, however on mine the caked-on dirt is a straight line covering the bottom 5-6" of the panels, not just the corners. the caked on dirt just looks terrible. it has been WEEKS here without any drop of rain, and the panels are pretty dusty again. we are planning some spring cleaning ourselves with some pressure washing and window cleaning and will probably have them do the panels just for our own research's sake this time.

I'll try to get the abstract for what I found 01/13 -01/14 dirty/clean sometime today. Preview : looks like about 1% penalty for ~ 3 months use.

J.P.M.