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I use the erbs model of pvlib to calculate dni and dhi from the global horizontal irradiance. However, my dni does not seem to be correct at the end of the day. I set the max zenith to 85 as is suggested here: Estimate diffuse and direct component from global irradiance

erbs = pvlib.irradiance.erbs(GHI_df['W/m2'], solpos['zenith'], GHI_df.index, min_cos_zenith=0.065, max_zenith=85)

Changing the max zenith to 85 made it a bit better. However, at the end of the day my dni still seems to give strange values. See the figure below. Does anyone know how to help.

enter image description here

Hoekieee
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  • This question does not really provide enough information. – adr Jun 12 '19 at 14:53
  • I'm having the same problem; were you able to find a solution? All I know so far is that it's related to daylight savings, but I can't fix it. – Lawrence Nov 19 '19 at 06:49
  • Same problem here. I've checked timezones, offsets, everything, and can't seem to fix it. Both Solar zenith and ghi show min/max at 12pm, yet DNI is like 1-3 hours off. did you ever find a solution? – Bobby Heyer Jan 31 '20 at 10:45

1 Answers1

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I suspect you have an offset in your timestamps, wrong time zone, or something like that.

adr
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