Re: [pysolar-discuss] Strange azimuth values

[Jay Doscher <jay@xxxxxxxxxxxxx>]

Looks like two curves to me, here's a graph of heading (corrected azimuth)
and elevation of my project.  Negative solar altitude simply means the sun
is below the horizon.

On Mon, May 11, 2015 at 4:41 AM, Frank Lazzarini <flazzarini@xxxxxxxxx>
wrote:

> When I apply the proposed method I get these results,
>
> [2015-05-10 00:00:00+00:25] Altitude: -22.817917957170042 Azimuth:
> 0.9195853796406368
> [2015-05-10 01:00:00+00:25] Altitude: -21.35437669913535 Azimuth:
> 16.282490410169657
> [2015-05-10 02:00:00+00:25] Altitude: -17.460113361911073 Azimuth:
> 30.88264446553194
> [2015-05-10 03:00:00+00:25] Altitude: -11.530293822218377 Azimuth:
> 44.334853539473784
> [2015-05-10 04:00:00+00:25] Altitude: -4.041985922217601 Azimuth:
> 56.64229429837951
> [2015-05-10 05:00:00+00:25] Altitude: 4.721075310609919 Azimuth:
> 68.08448558243651
> [2015-05-10 06:00:00+00:25] Altitude: 13.916416678430616 Azimuth:
> 79.1019578849806
> [2015-05-10 07:00:00+00:25] Altitude: 23.540263468364685 Azimuth:
> 90.25884449955726
> [2015-05-10 08:00:00+00:25] Altitude: 33.162952138663265 Azimuth:
> 102.29127881328759
> [2015-05-10 09:00:00+00:25] Altitude: 42.311459924908625 Azimuth:
> 116.22795411782772
> [2015-05-10 10:00:00+00:25] Altitude: 50.279286820496274 Azimuth:
> 133.49311577994877
> [2015-05-10 11:00:00+00:25] Altitude: 55.94436234658116 Azimuth:
> 155.49523632286264
> [2015-05-10 12:00:00+00:25] Altitude: 57.89747249155467 Azimuth:
> 181.6026287381771
> [2015-05-10 13:00:00+00:25] Altitude: 55.45948436540424 Azimuth:
> 207.40278382169132
> [2015-05-10 14:00:00+00:25] Altitude: 49.46294168127422 Azimuth:
> 228.8272461199938
> [2015-05-10 15:00:00+00:25] Altitude: 41.31880137304067 Azimuth:
> 245.63086306581897
> [2015-05-10 16:00:00+00:25] Altitude: 32.09659468953159 Azimuth:
> 259.28835550065156
> [2015-05-10 17:00:00+00:25] Altitude: 22.46665426651643 Azimuth:
> 271.18090530087704
> [2015-05-10 18:00:00+00:25] Altitude: 12.887187896956561 Azimuth:
> 282.29565250233105
> [2015-05-10 19:00:00+00:25] Altitude: 3.8032148272317357 Azimuth:
> 293.34291810798067
> [2015-05-10 20:00:00+00:25] Altitude: -4.854352153303335 Azimuth:
> 304.8696257443884
> [2015-05-10 21:00:00+00:25] Altitude: -12.152382809733522 Azimuth:
> 317.2976741424302
> [2015-05-10 22:00:00+00:25] Altitude: -17.83265833925366 Azimuth:
> 330.87639859009437
>
> On Sun, May 10, 2015 at 11:28 PM, Jay Doscher <jay@xxxxxxxxxxxxx> wrote:
>
>> I found the same issue, and managed to successfully offset it in my
>> python code.  A disclaimer though- this works for me in the southwest US,
>> and may be different elsewhere.
>>
>> def getsolarheading():
>>         Azimuth = Pysolar.GetAzimuth(maplat, maplon,
>> datetime.datetime.utcnow())
>>         if Azimuth < 0:
>>                 if (Azimuth >= -180):
>>                         solarheading = ((Azimuth * -1) + 180)
>>                 if (Azimuth < -180):
>>                         solarheading = ((Azimuth * -1) - 180)
>>         if Azimuth >= 0:
>>                 solarheading = Azimuth
>>         return solarheading
>>
>> This code will translate the Azimuth from Pysolar into a compass
>> heading.  I'm not sure what to tell you about altitude.
>>
>> Cheers,
>> Jay
>>
>> On Sun, May 10, 2015 at 2:05 PM, Frank Lazzarini <flazzarini@xxxxxxxxx>
>> wrote:
>>
>>> Hi there,
>>>
>>> when I run the following simulation I get really odd azimuth values.
>>> Well at least they seem odd, if I understood the documentation correctly
>>> they from ~90 over 0 to -90 degrees. When I run a simulation of an entire
>>> day I get really odd values for azimuth.
>>>
>>> from pysolar.solar import get_azimuth, get_altitude
>>> from datetime import datetime
>>> from pytz import timezone
>>>
>>>
>>> latitude = 49.707524
>>> longitude = 6.244362
>>> year = 2015
>>> month = 5
>>> day = 10
>>>
>>>
>>> def get_sun_position(latitude, longitude, time):
>>>     alt = get_altitude(latitude, longitude, time)
>>>     azi = get_azimuth(latitude, longitude, time)
>>>     return alt, azi
>>>
>>> tzinfo = timezone('Europe/Luxembourg')
>>> today = datetime.now(tz=tzinfo)
>>>
>>> for hour in range(0, 23):
>>>     time = datetime(
>>>         year,
>>>         month,
>>>         day,
>>>         hour,
>>>         0,
>>>         tzinfo=tzinfo
>>>     )
>>>     alt, azi = get_sun_position(latitude, longitude, time)
>>>     print("[{}] Altitude: {} Azimuth: {}".format(time, alt, azi))
>>>
>>>
>>> Now when I run this I get the following values
>>>
>>>
>>> [2015-05-10 00:00:00+00:25] Altitude: -22.817917957170042 Azimuth:
>>> -180.91958537964064
>>> [2015-05-10 01:00:00+00:25] Altitude: -21.35437669913535 Azimuth:
>>> -196.28249041016966
>>> [2015-05-10 02:00:00+00:25] Altitude: -17.460113361911073 Azimuth:
>>> -210.88264446553194
>>> [2015-05-10 03:00:00+00:25] Altitude: -11.530293822218377 Azimuth:
>>> -224.33485353947378
>>> [2015-05-10 04:00:00+00:25] Altitude: -4.041985922217601 Azimuth:
>>> -236.6422942983795
>>> [2015-05-10 05:00:00+00:25] Altitude: 4.721075310609919 Azimuth:
>>> -248.0844855824365
>>> [2015-05-10 06:00:00+00:25] Altitude: 13.916416678430616 Azimuth:
>>> -259.1019578849806
>>> [2015-05-10 07:00:00+00:25] Altitude: 23.540263468364685 Azimuth:
>>> -270.25884449955726
>>> [2015-05-10 08:00:00+00:25] Altitude: 33.162952138663265 Azimuth:
>>> -282.2912788132876
>>> [2015-05-10 09:00:00+00:25] Altitude: 42.311459924908625 Azimuth:
>>> -296.2279541178277
>>> [2015-05-10 10:00:00+00:25] Altitude: 50.279286820496274 Azimuth:
>>> -313.49311577994877
>>> [2015-05-10 11:00:00+00:25] Altitude: 55.94436234658116 Azimuth:
>>> -335.49523632286264
>>> [2015-05-10 12:00:00+00:25] Altitude: 57.89747249155467 Azimuth:
>>> -1.6026287381770885
>>> [2015-05-10 13:00:00+00:25] Altitude: 55.45948436540424 Azimuth:
>>> -27.402783821691315
>>> [2015-05-10 14:00:00+00:25] Altitude: 49.46294168127422 Azimuth:
>>> -48.82724611999379
>>> [2015-05-10 15:00:00+00:25] Altitude: 41.31880137304067 Azimuth:
>>> -65.63086306581897
>>> [2015-05-10 16:00:00+00:25] Altitude: 32.09659468953159 Azimuth:
>>> -79.28835550065156
>>> [2015-05-10 17:00:00+00:25] Altitude: 22.46665426651643 Azimuth:
>>> -91.18090530087704
>>> [2015-05-10 18:00:00+00:25] Altitude: 12.887187896956561 Azimuth:
>>> -102.29565250233105
>>> [2015-05-10 19:00:00+00:25] Altitude: 3.8032148272317357 Azimuth:
>>> -113.34291810798067
>>> [2015-05-10 20:00:00+00:25] Altitude: -4.854352153303335 Azimuth:
>>> -124.86962574438837
>>> [2015-05-10 21:00:00+00:25] Altitude: -12.152382809733522 Azimuth:
>>> -137.2976741424302
>>> [2015-05-10 22:00:00+00:25] Altitude: -17.83265833925366 Azimuth:
>>> -150.87639859009437
>>>
>>>
>>>
>>> Any ideas?
>>>
>>> --
>>>
>>> *Frank Lazzarini*
>>> *Email:* flazzarini@xxxxxxxxx  *Phone:* +352 621 314 430
>>> *Blog:*   http://www.gefoo.org   *LinkedIn:*
>>> http://www.linkedin.com/pub/frank-lazzarini/1a/a30/112
>>>
>>>
>>
>
>
> --
>
> *Frank Lazzarini*
> *Email:* flazzarini@xxxxxxxxx  *Phone:* +352 621 314 430
> *Blog:*   http://www.gefoo.org   *LinkedIn:*
> http://www.linkedin.com/pub/frank-lazzarini/1a/a30/112
>
>

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