Re: [pysolar-discuss] Strange azimuth values

[Brandon Stafford <brandon@xxxxxxxxxxxxxxx>]

That's a really cool project!

Frank, are you also using Pysolar 0.6, like Jay?

Brandon

On Mon, May 11, 2015 at 11:18 AM, Jay Doscher <jay@xxxxxxxxxxxxx> wrote:
> I'm building a portable PV tracker. It's not done, but it usually posts to
> Twitter every 3 hours as @SolarRobot7.  I am running pysolar 0.6 with Python
> 2.7.
>
> Thanks,
> Jay
>
> On Mon, May 11, 2015 at 8:13 AM, Brandon Stafford <brandon@xxxxxxxxxxxxxxx>
> wrote:
>>
>> Hi Jay,
>>
>> That's a beautiful pair of charts! Is that a PV tracker you're building or
>> what?
>>
>> One other question: what version of Pysolar are you needing to make
>> azimuth corrections with?
>>
>> Brandon
>>
>> On Mon, May 11, 2015 at 10:48 AM, Jay Doscher <jay@xxxxxxxxxxxxx> wrote:
>> > 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
>> >>
>> >
>>
>>
>>
>> --
>> Brandon Stafford
>> Rascal Micro: small computers for art and science
>> Somerville, MA, USA
>> --
>> To unsubscribe send a blank message to
>> pysolar-discuss+unsubscribe@xxxxxxxxxxx
>>
>



-- 
Brandon Stafford
Rascal Micro: small computers for art and science
Somerville, MA, USA
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