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Solar/UV Info

From build 3044 the development baton passed to Mark Crossley. Mark has been responsible for all the Builds since. He has made the code available on GitHub. It is Mark's hope that others will join in this development, but at the very least he welcomes your ideas for future developments (see Cumulus MX Development suggestions).

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mcrossley
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Re: Solar/UV Info

Post by mcrossley »

But in winter a sunny day would be much less hours wouldn't it? Personally I'd define it as a percentage of the possible sunshine hours in a day that are sunny.
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Re: Solar/UV Info

Post by Cambium »

mcrossley wrote: Fri 20 May 2022 4:49 pm But in winter a sunny day would be much less hours wouldn't it? Personally I'd define it as a percentage of the possible sunshine hours in a day that are sunny.
Very true again. Good idea grabbing the percentage of it for that day. Thanks!
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Re: Solar/UV Info

Post by PaulMy »

True.. I guess using 8hrs+ for a full sunny day looks like only 9 out of past 30 days.
The beteljuice/BCJK Annual Data scripts shows graphically the sunshine in comparison to maximum for the day (select Sunshine tab) http://www.komokaweather.com/cumulusmx/ ... hp?lang=en
The B-L Sunrecorder displayed graphs also based on time of year.

The Solar tab shows from May 2018 when the VP2 was replaced by a VP2 Plus with Solar and UV.

Enjoy,
Paul
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Cambium
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Re: Solar/UV Info

Post by Cambium »

PaulMy wrote: Fri 20 May 2022 5:09 pm
True.. I guess using 8hrs+ for a full sunny day looks like only 9 out of past 30 days.
The beteljuice/BCJK Annual Data scripts shows graphically the sunshine in comparison to maximum for the day (select Sunshine tab) http://www.komokaweather.com/cumulusmx/ ... hp?lang=en
The B-L Sunrecorder displayed graphs also based on time of year.

The Solar tab shows from May 2018 when the VP2 was replaced by a VP2 Plus with Solar and UV.

Enjoy,
Paul
Very cool! So that spot in Canada has gotten almost double the amount of days since April 19rh with 8+hrs of sun than here at the CT coast.
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Re: Solar/UV Info

Post by Cambium »

Anyone know how Cumulus calculates the sunshine hours from the Ecowitt station?
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Re: Solar/UV Info

Post by mcrossley »

It's the same for all stations, the sunshine is deemed to be when the solar value exceeds both the threshold value and the percentage of theoretical value.
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Re: Solar/UV Info

Post by Cambium »

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Last edited by Cambium on Tue 30 Jan 2024 4:56 pm, edited 1 time in total.
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Re: Solar/UV Info

Post by Cambium »

mcrossley wrote: Sat 21 May 2022 1:01 pm It's the same for all stations, the sunshine is deemed to be when the solar value exceeds both the threshold value and the percentage of theoretical value.
Can you elaborate on this? I'm trying to find my sunshine hours from missing data but Ecowitt doesn't list sunshine hours. So trying to figure out how Cumulus creates the sunshine hours data

Thank You
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Re: Solar/UV Info

Post by Gyvate »

look at Settings --> Station settings --> Solar
there the methods for calculation sunshine hours from the Wattage (W/m2) readings received from a console are shown.
You want to know the details of these methods, Google is your friend.
e.g. https://agupubs.onlinelibrary.wiley.com ... 06WR005055
http://www.ecy.wa.gov/programs/eap/models.html

the Ecowitt consoles do not provide sunshine hours - CMX calculates them from one of two models assuming that once a threshold of a percentage of theoretical maximum solar irradition is crossed, this means sunshine. The time (seconds, minutes) are accumulated.

Or, as I do it, CMX uses the input from my Blake-Larsen Sunrecorder which determines sunshine as the human eye would do. The software of the recorder adds the seconds of sunshine (again a threshold of an electrical current created by incoming sunlight is taken as reference) and provides an update of accumulated sunshine time every minute to CMX.
B-L-Sunrecorder_example.jpg
20230911.png
in CMX today/yesterday (29-Jan/30-Jan-2024)that would then look like this: (whereas the above pictures are from 2023-09-11)
B-L-Sunrecorder_example-in-CMX.jpg
as not everybody has such a device, approximation models exist - and they are used by CMX (you can choose one of them, see above) or use e.g. the Blake-Larsen SunRecorder which doesn't give an approximation but the equivalent what a human eye would perceive if the light hit the retina. The B-L SunRecorder simulates a human eye in the distinction if for it there is sunshine or not. Quite a smart piece ...
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Re: Solar/UV Info

Post by Cambium »

Gyvate wrote: Tue 30 Jan 2024 5:40 pm look at Settings --> Station settings --> Solar
there the methods for calculation sunshine hours from the Wattage (W/m2) readings received from a console are shown.
You want to know the details of these methods, Google is your friend.
e.g. https://agupubs.onlinelibrary.wiley.com ... 06WR005055
http://www.ecy.wa.gov/programs/eap/models.html

the Ecowitt consoles do not provide sunshine hours - CMX calculates them from one of two models assuming that once a threshold of a percentage of theoretical maximum solar irradition is crossed, this means sunshine. The time (seconds, minutes) are accumulated. ...
Interesting! Thank You! I can google Ryan Stolzenbach but you guys are smarter and can explain it in laymans terms plus Google might redirect someone to this thread.

"The percentage of the current theoretical solar value above which the sun should be considered to be shining (default = 75%)"

What happens if I raise that percentage to 90? Is it more sensitive and would capture sunlight hours more?
Solar.jpg
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Re: Solar/UV Info

Post by Gyvate »

no - it means that you will most likely get less sun hours as 90% is a higher threshold than 75% (unless the real sunshine equals anyway always 90% of the theoretically possible)
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Re: Solar/UV Info

Post by Cambium »

Gyvate wrote: Wed 31 Jan 2024 9:42 pm no - it means that you will most likely get less sun hours as 90% is a higher threshold than 75% (unless the real sunshine equals anyway always 90% of the theoretically possible)
So noticing finally the sun is shining this morning but Cumulus still showing 0.0hrs. What setting should I adjust? Seems like its not sensitive enough?

Sun been shining for at least 30 minutes now. The station has been receiving direct sun too (Its on the roof)

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Re: Solar/UV Info

Post by mcrossley »

You need to look at the recent solar graph and compare the value from your station with the theoretical max. Post the graph for today so we can see.

Calibration in mid winter is pretty tricky anyway, the solar values are so low. Ideally you still it on a clear day in mid summer.
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Re: Solar/UV Info

Post by Cambium »

mcrossley wrote: Sat 03 Feb 2024 2:09 pm You need to look at the recent solar graph and compare the value from your station with the theoretical max. Post the graph for today so we can see.

Calibration in mid winter is pretty tricky anyway, the solar values are so low. Ideally you still it on a clear day in mid summer.
Thanks Mark... I figured winter has something to do with it. If there's a way to offset that I'm all ears.

Here is the chart. Sun still shining outside so its about 1.5hrs of sunshine this morning

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Here are my settings.. I changed the threshhold to 70 and the minimum to 25 hoping it made a difference.

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Re: Solar/UV Info

Post by mcrossley »

OK, so it is looking way out. The theoretical value is up around 240 at the end, but your station is only reading 115 W/m2

I see your station has a light sensor (lux) rather than a solar sensor, so Cumulus MX will be converting lux to W/m2.
Which station type do you use in Cumulus?
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