soiling city [RE-wrenches]

[Joel Davidson]

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Sprinkling an array or dew on an array can catch dust and dirt and increase 
the amount of soiling. I suggest picking an acceptable soiling loss (for 
example 2% or 4%), monitoring the array and hosing it down when you think it 
needs it.

Powerlight paper abstract:
The accumulation of dirt on solar panels ("soiling") can

have a significant impact on the performance of PV

systems in regions where rainfall is limited for a dry

season of several months. This effect is magnified where

rainfall is absent in the peak-solar summer months, such

as in California and the Southwest region of the United

States. This paper describes the effects of soiling on

energy production for large grid-connected systems in the

US and presents a model for predicting soiling losses.


I have a copy of the paper.

Joel Davidson


----- Original Message ----- 
From: "Nick Lucchese" <nickl at sierrasolar.com>
To: <RE-wrenches at topica.com>
Sent: Thursday, June 29, 2006 5:31 PM
Subject: Re: soiling city [RE-wrenches]



  A study posted at the World PV Conference in
Hawaii last month stated that soiling in dry
climates was found to decrease panel output by
.2% each day without rainfall.  This equated to
an annual energy loss due to soiling by as much
as 2-6% depending on amount and frequency of
rainfall in the region. It went on further to say
that rainfall events of .2 to .3 inches were
required to fully clean a PV system regardless of
the severity of soiling. I believe the study was
performed by Powerlight on large systems, perhaps
in their home region of northern California. I
think I still have a high res picture of the
poster it was on if anyone is interested. It's
quite small but you can zoom in clearly with
Iphoto etc.

Nick A Lucchese





>I've got a roof-mounted array on an essentially flat roof in an area that 
>is
>very dusty with little rainfall.  I'd appreciate knowing what the estimated
>percentage reduction in output might be for such a heavily dusty area
>compared to a light soiling location.  I'm thinking about rigging up a rain
>bird kind of sprinkler to hose down the 16 kW array every day for 15 
>minutes
>in the early AM hours as a way to keep the glass cleaner.  Has anyone out
>there put something like that together?  With the hard water in the area, I
>figure that I would need to condition the water used to hose down the array
>to minimize the mineral build-up on the glass and frames.
>
>Thanks,
>marco
>
>
>Marco Mangelsdorf
>Electrical Contractor License C-26351
>69 Railroad Avenue, A-7
>Hilo, Hawai'i 96720
>(808) 969-3281, 934-7462 facsimile
>www.provisiontechnologies.com
>
>
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--
Nick A Lucchese
NABCEP Certified PV Installer
General Contractor # 808851
Sierra Solar Systems
563C Idaho Maryland Road
Grass Valley, CA 95945
tech info and foreign orders:  (530) 273-6754
order line: (800) 51-SOLAR (US only)   FAX:  (530) 273-1760
e-mail:  <mailto:nickl at sierrasolar.com>
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Voted Best Solar Company 2003 and 2004 by Union Readers

Because of the high volume of e-mail to which I respond, please
leave _all_ of the previous messages (unless it's unbearable) in
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