Nrel Data conversion
ajit.nayak87
Posts: 76
Dear all,
I have downloaded Nrel data from https://www.nrel.gov/midc/solpos/spa.html from Below link. I would like to Top. azimuth angle (eastward from N) and
Top. azimuth angle (westward from S)
meant in pdf file attached.
How to calculate sun elevation angle here
. Since we measuring elevation angle from East to west . what is formula to calculate the SUn elevation angle from East to west using zenith and azimuth angle.
NREL data.pdf
I have downloaded Nrel data from https://www.nrel.gov/midc/solpos/spa.html from Below link. I would like to Top. azimuth angle (eastward from N) and
Top. azimuth angle (westward from S)
meant in pdf file attached.
How to calculate sun elevation angle here
. Since we measuring elevation angle from East to west . what is formula to calculate the SUn elevation angle from East to west using zenith and azimuth angle.
NREL data.pdf
Comments
I'm not sure I fully understand what you are asking but if you need to know the elevation and azimuth of the sun from a given location on the Earth at a given time everything yo u need to know is in suncalc.
https://github.com/mourner/suncalc
The code is in Javascript (see suncalc.js) but is easy to read and understand. Could be easily rewritten in C or Java or whatever you like.
The zenith is strait up over your head.
To convert zenith to elevation:
(zenith angle) -180deg = ELevation
So ELevation angle is 180deg strait up, 0deg at the horizon, and -180deg strait down.
Azimuth is measured from due North, 0deg, through East, 90deg, South, 180deg, and around to North, 360deg or 0deg.
Note! the NREL data doesn't take into account the atmospheric refraction near the horizon.
There is no refraction at the zenith and maximum near the horizon. This error is generally less than 1.7deg of altitude or so and dependent on the barometric pressure, phisical altitude above sea level, and temperature. This correction is easy to calculate and generally unimportant for solar power applications less than 10deg of altitude.
If you need more info about the ALTitude refraction correction I can give you my info. Email me at redrok@redrok.com.
Duane J