According to the documentation if the solar radiation is missing from the input weather file, WeatherConverter will calculate the global horizontal solar radiation using an early version of the Zhang-Huang Model, which uses as inputs the sky cover, temperature change over 3 hours, wind speed, and relative humidity (at least in my original formulation). Therefore, you should make sure that the sky cover is present in the input weather file, and not always set to 0. Although the documentation fails to say, presumably the WeatherConverter then uses the Perez Model to calculate the direct normal solar radiation from the calculated global horizontal.
There is an increasing availability of recorded weather station data on the Web, but none of that contains measured solar radiation. Even in the National Solar Radiation Database (NSRDB) that covers 1991-2010 for 1,454 US locations, the solar has been derived using a METSTAT Model. A recent development is the increasing use of satellite imagery to estimate solar radiation. The NSRDB also has online 10-km gridded solar data, again for 1991 through 2010. Same information for later years or other parts of the world are available commercially, but they are not free.
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://weather.whiteboxtechnologies.com for simulation-ready weather data (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 8/28/2013 8:46 AM, qureshi.faran wrote:
I have the measured historic yearly weather data in csv format. I'm missing most of the solar radiation related data. I want to know that which fields are the mandatory for the computation of the solar radiations, by the Energy plus weather file conversion utility.
I would also appreciate, if someone can point out to a free resource of historic measured weather data in epw format (containing all the fields, including the solar radiations).
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