soiling city [RE-wrenches]

[Peter Parrish]

Nick, if I do the math, 0.2% times 100 days (southern CA) yields a 20% loss
which is much greater than anything I've heard of. The only thing I can
think of is that the 0.2% applies to the 1-5% tilt angles for Powerlight
tiled products.

- Peter

Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave.
Los Angeles, CA 90065
Ph 323-258-8883
Mobile 323-839-6108
Fax 323-258-8885
peter.parrish at calsolareng.com 


-----Original Message-----
From: Nick Lucchese [mailto:nickl at sierrasolar.com] 
Sent: Thursday, June 29, 2006 5:31 PM
To: RE-wrenches at topica.com
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>
world wide web:  <http://www.sierrasolar.com>

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
   your reply so I can better remember your original message.


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