"t...@tom.org" <t...@tom.org> writes: > kk, glad you corroborated my observations. I am no expert in this for sure. > I am just tired of all of the comments I get from visitors to the website > about how my readings exceed theoretical max. I could remove the max, but > that doesn't seem fun.
I have added maxSolarRad to my db and am now looking at it. This morning, I saw values that exceeded theory right at dawn, then going under theory after a while. Two thoughts from this: Instruments are typically specified at something like 5% of full scale. I just looked up the VP2 and that is exactly what it says. So that's 5% of 1800 W/m^2, or 90 W/m^2. That's huge compared to morning levels. The theory is presumably for a sensor that is somewhat off the ground in an open area with not only no trees but no buildings. A light-colored building nearby might reflect light from direct sun. > I do not have the expertise to validate the way weewx calculates it nor am > I even competent in Python, but for those who may, here is a link to the > code: > > https://github.com/weewx/weewx/blob/d91635f3bc429f906d1f084c6a6bc8ee09fa1a27/bin/weewx/wxformulas.py#L332 Thanks. That seems to refer to fairly old work (which doesn't mean it's wrong, but it seems there has been a lot more attention paid to this more recently). With any luck someone can go over the various theory papers and implement a few more algorithms. This looks like the state of the art: https://pvpmc.sandia.gov/modeling-steps/1-weather-design-inputs/irradiance-and-insolation-2/irradiance-data-sources-for-performance-modeling/national-solar-radiation-database/ but my guess is that using the Wikipedia article is going to be easier. -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/rmilfdquejd.fsf%40s1.lexort.com.
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