[RE-wrenches] Power Factor

[David Brearley]

Ron,

Here is a definition for Power Factor that we used in our String Inverter
guide in SP1.1:

POWER FACTOR AT RATED OUTPUT
Definition: The ratio of true power to apparent power in the inverter ac
output circuit at its rated power.
Importance: True power is measured in units of watts and describes the
ability to do useful work. Apparent power includes both work-producing power
and reactive power measured in volt-amperes. Power factor is a comparison of
watts to volt-amperes or real power to apparent power in an ac circuit. If
the power factor in a circuit is 1.0, then all of the power generated is
available to do useful work.

The point is that you can describe the power factor for an inverter‹it
approaches unity (see the Table in SP1.1)‹but this does not apply for PV
modules. You can simply write ³NA² in the space provided. If they ask why,
the simplest explanation it that PV modules are part of a DC circuit and
power factor applies to AC circuits. It¹s not at all uncommon for
interconnection documents to request information that is not applicable to
PV systems.

Best,

David Brearley, Senior Technical Editor
SolarPro magazine 
NABCEP Certified PV Installer 
david.brearley at solarprofessional.com
Direct: 541.261.6545
Fax:  541.512.0343

Visit our Web site at solarprofessional.com

(Sample copy available for download at: solarprofessional.com/sample)


On 7/30/09 2:00 PM, "Ron Young" <solareagle at solareagle.com> wrote:

> Ok, so all seem to be in agreement more or less. How do I break it to British
> Columbia Hydro? :-|
> 
> I think they must be misunderstanding what they are asking for but the
> question is in the section for PV and on the same line as the total output in
> Kwh of the PV. Power Factor %
> 
> I'll contact them and see where this goes but I don't fully understand what
> power factor is which will make it hard to argue my case. My understanding is
> that it is the difference between what the utility supplies to a residence vs.
> the actual loads being used by that residence expressed as a percentage.
> 
> I came across the following course offering by SEI that discusses Power Factor
> with reference to PV:
> 
> POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS
> Presented By: Michael Smith of Alpine Management Systems
>  
> This session will deal with power factor: What is power factor?  What causes
> low power factor?  Why improve
> your power factor? This session will explain the role of power factor
> correction as it applies to solar installations.
> There are currently over 67,000 KVAR installations in 26 countries resulting
> in phenomenal energy savings with
> a corresponding reduction in greenhouse gas emissions. Session includes
> several KVAR installations and the
> resultant savings.
> http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf
> 
> Ron
> 
> On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:
> 
>> There is no such thing as a power factor for DC or for panels.
>>  
>> .............................................................................
>> .....................
>> Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
>> Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
>> .............................................................................
>> .....................
>>> ----- Original Message -----
>>> From: Ron Young <mailto:solareagle at solareagle.com>
>>> To: RE-wrenches <mailto:re-wrenches at lists.re-wrenches.org>
>>> Sent: Wednesday, July 29, 2009 5:45 PM
>>> Subject: [RE-wrenches] Power Factor
>>> 
>>> Can anyone point me in the direction to find the power factor for Sanyo HIT
>>> N 205 panels? The utility is requesting it on a net metering interconnection
>>> application.  
>>> 
>>> Ron Young
>>> earthRight Products - Solareagle.com
>>> 
>>> 
>>> 
>>> 
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