[pvusers] Re: [distributed-generation] (unknown)

[Renewable News Network <rnn@rnn.com>]

Good question.

One might need more information, specific to both the panels and the
overall system, and the location (insolation at that Latitude,
cloudiness factor, and possible microclimatic conditions.)

One might even ask for the manufacturer's boiler plate info and/or
tested performance if you have that.

A few other questions that may or may not be pertinent:

> Output: 238 kWh

ac? dc? the whole system?
what's the time period?
what's the application?

> Ambient Temperature: 9 degrees centigrade

not a factor in that range

> Wind Speed: 3.5 m/sec

not a factor (unless this is part of a hybrid unglazed thermal system)

> DNI:53 kWh/m2
> GHI:58 kWh/m2

what's DNI? GHI?

> Rating: 3.45 kWac

this must be the capacity of the whole system?
where is the inverter fitting into the picture?

> Gross Area: 35.9 m2

orientation? tilt?


Finally, what are you really after?  Since efficiency is a ratio of
output over input, it's difficult "to calculate efficiency of a PV
installation" without first getting the terms clarified (e.g dollars
in versus dollars out?)  Are you comparing a system with these known
specifications to the same setup in another location?

Yours truly,
Ross Donald

On Fri, 1 Feb 2002, Rao Konidena wrote:

> Dear Group!
>
> Can somebody help me to calculate efficiency of a PV installation with
> these details:
>
> Output: 238 kWh
> Ambient Temperature: 9 degrees centigrade
> Wind Speed: 3.5 m/sec
> DNI:53 kWh/m2
> GHI:58 kWh/m2
> Rating: 3.45 kWac
> Gross Area: 35.9 m2
>
> I think I am looking for some formula that basically involves the weather
> component in efficiency calculation.
>
> Thank You,
> Rao
>
>
> ***********************************************************
> Rao Konidena
> IEEE-Chair
> EE Representative on Graduate Student Council,
> Graduate Student,
> Energy Systems Research Center,
> Univ of Texas at Arlington,
> TX-Arlington-76019
> email:konidena@ieee.org
> Ph:817-272-5048
> ***********************************************************
>
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