Author Topic: Solar Radiation calibration  (Read 130 times)

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Offline Goldguru

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Solar Radiation calibration
« on: January 08, 2021, 06:18:02 PM »
I have a fine offset GW1000 with a wh68 anemometer/lux sensor & CMX
am I barking up the wrong tree to assume on the gauges page when my mouse is hovering over solar radiation gauge & it states "theorectical max = XXX Wm2
that CMX is using the stations variables to generate that number? via temp RH dew point etc

If so can I use this Theo/max # to adjust my lux sensor to get into range of Theo/max?

today is the 1st clear day since the station has been in use.
theo/max was ~ 240 & gauge read 92, so I adjusted my solar rad gain to
2.61 using the WSview app & achieved a number which CMX says = 97% of Theo/Max.

I know its not possible to convert Lux to a true solar sensor,however I figured that if CMX was providing a realistic/ish # then i would just fondle my gain to get into the neighbourhood of the Theo/Max that CMX is calculating.
Since making this change hovering my mouse over the solar rad gauge i'm generaly showing 95-98% of The/Max over a 2 hr period.

I also realise this # really has no true relationship to wm2 However I would like my solar chart to be some what consistant with conditions/TheoMax.
I also realise this is not the time of year to be exspecting reliable results due to the sun angle.
Thnx Gold

Offline mcrossley

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Re: Solar Radiation calibration
« Reply #1 on: January 09, 2021, 06:04:59 AM »
The theoretical max just uses your lat/long, time, and the atmospheric "transparency" value that you select for whichever calculation you choose.

I find that in general the transparency varies with slightly with time of year (in the UK at least). Being more transparent in winter and less in summer. I tweak the value slightly in autumn and spring based on my historic data.

And you are correct, the best time to make the adjustments is on a really clear day around the summer solstice.