Wire Sizer Spreadsheet [RE-wrenches]

[Ray Walters]

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I got so many requests for the wire sizer, I updated the version on  
the website (much simpler now) here it is:
http://www.solarray.com/TechGuides/Downloads/WireSizer.xls

The resistance, volt drop, & temp compensation are based on NEC 2005.  
I don't think it changed for 2008.
You can all use it/ modify it freely, distribute it to students, etc.  
just give us credit please.

As always, your feedback/ criticisms will be greatly appreciated.

Ray
ray at solarray.com

On May 1, 2008, at 7:06 PM, Ray Walters wrote:

>
>
> Do they also ask the panel orientation relative to azimuth and tilt?
> I've used NREL's PVWATTs calculator that lets you program in the  
> panel orientation and computes (I believe) total KWh/ day based on  
> direct normal + diffuse radiation.
> I think you would need to look at both for flat plate, while  
> concentrators would only use the direct normal number.
>
> Ray
>
>
> On May 1, 2008, at 6:25 PM, Allan Sindelar wrote:
>
>>
>>
>> Wrenches,
>> I have registered and used www.firstlook.3tiergroup.com for the first
>> time. It looks like a powerful resource, especially as it can  
>> serve as a
>> documentable reference for solar and wind assessment data used in  
>> system
>> designs. One question I need help with, please:
>>
>> PV-relevant solar data is offered as either "direct normal  
>> irradiance",
>> defined as:
>> 	"the amount of direct radiation received per unit area by a
>> surface that is always held perpendicular (normal) to the rays  
>> that come
>> directly from the direction of the solar disk in the sky. By  
>> keeping the
>> surface normal to the incoming radiation, you maximize the amount of
>> energy received. This quantity of particular interest to  
>> concentrating
>> solar installations and installations that track the position of the
>> sun."
>> or "global horiziontal irradiance", defined as:
>> 	"is the total amount of shortwave radiation received from above
>> by a horizontal surface. This value is of particular interest to
>> photovoltaic installations and includes both direct radiation and
>> diffuse radiation.
>> 	Direct radiation is solar radiation that comes from the
>> direction of the solar disk in the sky. Diffuse radiation is solar
>> radiation that has been scattered by molecules and particles in the
>> atmosphere and comes equally from all directions.
>> 	On a clear day, most of the solar radiation received by a
>> horizontal surface will be direct radiation, while on a cloudy day  
>> most
>> will be diffuse radiation."
>>
>> Which figure should PV designers use? It looks to me as though direct
>> normal irradiance, which is a higher figure (kilowatt-hours/meter
>> squared/day) would be best for a two-axis tracking array that always
>> faced the sun. But global horizontal irradiance would be lower than
>> accurate, as our typically seasonally-adjusted arrays are not
>> horizontal, yet neither do they follow the daily sun path.
>>
>> Who can advise a good compromise, or other approach that is  
>> defensible
>> using this data?
>> Thanks,
>> Allan Sindelar
>> allan_(at)_positiveenergysolar.com
>> <mailto:allan at positiveenergysolar.com>
>> NABCEP certified solar PV installer
>> Positive Energy, Inc.
>> 3225A Richards Lane
>> Santa Fe NM 87507
>> 505 424-1112
>>
>>
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>>
>>
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>
> R. Walters
> Solarray.com
> NABCEP # 04170442	
>
>
>
>
> --
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>
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> Hosted by Home Power magazine
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>
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> wrenches/read
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R. Walters
Solarray.com
NABCEP # 04170442	




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