Benn,

At 25 ft a 1-inch power line subtends an angle of 0.2 degree.  The sun subtends an angle of  0.5 degree, so the power line will not make a dark shadow on the modules - only 50% of the light can be blocked.  Depending on the distance from the module to the wire, along the ray to the sun, the wire will probably block a little less light.  But a 50% reduction in the light on a few cells will probably reduce the entire module output by 50%.  A shadow every day for the hours you are talking about sounds like a pretty serious issue.

Kent Osterberg
Blue Mountain Solar


benn kilburn wrote:
Thanks for the feed back guys, much appreciated!  

Now, how would you calculate for power/phone lines running thru the Pathfinder's reflection.  There are about 6 of them (the largest being at least 1") at least 25-30 ft away directly east of the proposed array location, and they are running straight north-south.  On the Pathfinder they run btwn 9 and 11am in June and btwn 10:30 and 11:30 in December.  

Would the pathfinder software, suneye or asset pick up on utility lines at that distance?  How much effect do they have on available sun output? And while i'm at it, how much do the 'software' tools pick up on the tips of leafless tree branches at say 25ft, 50ft?

i'll try out that spreadsheet idea, nice one!

cheers,
benn

DayStar Renewable Energy Inc. 
780-906-7807 
HAVE A SUNNY DAY




Date: Wed, 8 Sep 2010 20:05:08 -0700
To: [email protected]
From: [email protected]
Subject: Re: [RE-wrenches] Wiley Asset

Benn:

A colleague has used the Wiley took and calls it 'marginal.'

I use the Pathfinder and I like the features Ray described.  I wrote a very simple spreadsheet using the teeny numbers on the month lines to create 100% of any month.  I highlight and delete any of the numbers that are shaded and the remainder is the percent of exposure for a given month.  You can multiply the output of PV watts or any other production result for a complete production prediction.  Easy and free.

William Miller


At 05:38 PM 9/8/2010, you wrote:
I've used the Pathfinder for decades, so I'm partial to them. Great for on-site discussions of shading issues with the customer, as multiple people can see the shading at the same time on the spot.
I've also used their Assistant software, and it works pretty well. You take a photo of the actual pathfinder from above, and then download the photo into their software.
You can then calculate total annual impact of any shading in Kwh, or percentage of annual production.
I've been quite happy with the system, and the price for a Pathfinder, and the software is much less than the Suneye, I believe.

R. Walters
[email protected]
Solar Engineer




On Sep 8, 2010, at 3:46 PM, benn kilburn wrote:

Wrenches,

I'm looking at trying out another 'solar site evaluation tool', the ASSET (Acme Solar Site Evaluation Tool) from Wiley Electronics.  I'm looking for feedback on its performance and user-ability.
I have been using the pathfinder which is great, but not the pathfinder software.

Any comments on the ASSET or Pathfinder software would be greatly appreciated.

Cheers,
benn

DayStar Renewable Energy Inc.
[email protected]
780-906-7807
HAVE A SUNNY DAY

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