Real-time solar data : azimuth, Altitude, Lux sensor... [closed]

[jmleglise]

This script is documented in the wiki : http://www.domoticz.com/wiki/Real-time_ ... _sensor...

Edit 19 March 2016 - V1.4 - Take the last version of this script in the wiki. http://www.domoticz.com/wiki/Real-time_ ... structions

Edit 3 sept 2017 - V2 - The script is now translated in dzevent framework http://www.domoticz.com/forum/viewtopic ... 59&t=19220

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Hi everyone,

This LUA script calculates in real-time a lot of usefull solar data without any hardware sensor. The result is very satisfactory. I hope you will enjoy it.

Data :
Azimuth : Angle between the Sun and the north, in degree. (north vector and the perpendicular projection of the sun down onto the horizon)
Altitude : Angle of the Sun with the horizon, in degree.
Lux : radiation of the sun with real time cloud layer
and many more

The calculation is based on the theoretical radiations of the sun according to its location in the sky, calculated according to the time and the number of day in the year, plus the real-time cloud layer and the real-time weather (pressure) :
- Geographical address
- Altitude of the geographical point
- Atmospheric pressure of the place / from api.wunderground.com
- The cloudiness in Octa (1/8) / from ogimet.com

-- What is it For ? ------------------------------------------------------
Manage exactly roller blinds and venetian blind. both to optimise the heating and to prevent dazzle.
Manage your light according to the Luminosity
Use civil twilight dawn and dusk (-6 deg altitude) instead of sunrise and sunset.
Some calculation about photovoltaic production ?
Automate the heating of swimming pool
Personally I use a roller blind to wake up instead of an alarm clock, with a progressive opening of the roller blind to prevent dazzle.

-- History ------------------------------------------------------
I have improved the huge work of Sébastien Joly (on an another automation system) that Neutrino has migrated to Domoticz.

I deeply encourage you to visit the very interesting, original post in French : http://www.domotique-info.fr/2015/09/ou ... ecenter-2/
And the others documentations and source of the formulae :
http://www.plevenon-meteo.info/techniqu ... ement.html
http://herve.silve.pagesperso-orange.fr/solaire.htm
https://en.wikipedia.org/wiki/Azimuth
https://en.wikipedia.org/wiki/Dawn
There was even already a first implementation of these formulae here http://www.domoticz.com/forum/viewtopic.php?f=23&t=6793, but I choose to complete the other implementation.

[Westcott]

Hi Jmleglise,

Thanks for posting, it looks fascinating.
But, how do you use it with Domoticz?
It fails by complaining about 'local'.
However, I found the file JSON.lua after a bit of Googling.

[jmleglise]

Hi westcott

I have created a page in the wiki for the library json.lua here : http://www.domoticz.com/wiki/Lua_-_json.lua
This is a commun library, used in several other scripts of this forum. In fact, you need it as soon as you want to request the api of Domoticz.

And for your question : Did you get an error on line 28 ? => of course you need to set up your own latitude in line 28 as well as set up all parameters.

I don't know your skill in lua, but for this kind of script, you have to invest a little time and read a least once every line and comments.

[styxxen]

Hey,
I implemented your script yesterday, and I must say that it works really well. Good Job!
I have a question though, the API calls are running through the roof,and I am already up to 199 API calls to Weather Underground today (time now is 10:15)
So how can I edit your script to not go over the 500 calls/day limit?

This is actually my first attempt at LUA-scripts, so I took the easy way and chose to do it through the "Events" system as a LUA script, and chose "Time" as script type.
The script now runs every minute, which I guess is fine, as long as the API calls are not performed every minute.
So do you have any tips on what to change in your script on line 52 to not have it making http request every minute?

time = os.date("*t")
if ((time.min % 1)==0) then -- remember the wundergroud limitation

[styxxen]

OK, I think I can answer my own question

time = os.date("*t")
if ((time.min % 5)==0) then -- remember the wundergroud limitation

That will make the script run every 5 minutes, which solves the API limit-issue

[Westcott]

Well, I'm getting further.
Any idea how I know which 'City' to use?
I live right out in the country, not near a city.
However, not even 'London' works!

UPDATE

Changing 'FR' to 'GB' in the call to 'curl http://api.wunderground.com/api/' helped a bit!
Now I can get 'London'
But how to get my own PWS?
For the moment, I've set it to a nearby place, and run the call successfully in the browser.
But running the Lua now gives -
Error: EventSystem: /home/pi/domoticz/scripts/lua/script_time_weather.lua:77: attempt to index field 'current_observation' (a nil value)
apparently in -
local latitude = jsonLocation.current_observation.display_location.latitude
but this seems unlikely,

Debugging continues...

BTW I'm a retired .Net and Unix programmer.

[styxxen]

Hi,
You need to Edit this row:

local config=assert(io.popen('curl http://api.wunderground.com/api/'..wuAP ... ty..'.json')) -- customize here !!

Paste in you APIkey where it says ..wuAPIkey..
Change /FR/ to /GB/ (or whatever countrycode WU uses for UK.
Paste in London where it says ..city..


Sent from my iPhone using Tapatalk

[jmleglise]

Both for the problem of API limitation, and the problem of living in the middle of nowhere : The City and the wunderground API are only used to get your local Pressure. (search the "relativePressure" variable to understand). This has a low impact on the formulae (while the cloud layer has a big one for example).

1/ You don't need to use Weather underground nor the city if you already have a barometer sensor (value in hPa). Use it instead and save some API Calls :
- you may already use the virtual Hardware type "Weather underground" ? (If so, remember, you already have an APi key , look in the Setup / Hardware page of Domoticz).
- Or perhaps do you have an hardware Temp sensor outside with Pressure ?

2/ you can simply remove City and wunderground and not use the Pressure by setting "relativePressure" in the script to an average value like 1024.

3/ or you can search the Wunderground doc (http://api.wunderground.com/weather/api/d/docs) to find if you can use it with Lat. and Long. without the name of a City. I don't know.

[Westcott]

Thanks for the detailed reply!
I'll go for option 1 - I have my own Wunderground PWS ( IENGLAND873 ) with my API key in the script.

[stefanvn]

Thanks for the script, this works great!
I also wanted to use this script to switch the lights in and around the house, based on the amount of light. However, if I try to retrieve the Lux-value in a separate LUA script with the "otherdevices_svalues command, I'm constantly getting an error.

The code I'm using:

Code: Select all

commandArray = {}
  Luxvalue = otherdevices_svalues['Lux']
  return commandarray

The error message when I run the script in terminal:

lua: script_time_Duskswitchonlux.lua:3: attempt to index global 'otherdevices_svalues' (a nil value)
stack traceback:
script_time_Duskswitchonlux.lua:3: in main chunk
[C]: ?

Can you share with me how you have setup your scripts, based on the Lux value?

Thanks in advance for your reply.

[jmleglise]

Lux is for me a virtual device of type Lux and subtype Lux, named 'Lux". svalues is a string. So to use it you must convert it to a number. like this :

if tonumber(otherdevices_svalues['Lux'])>1000 then


Does it help ?

[stefanvn]

Hi Jimlegise,

Thanks for your reply. I tried your suggestion in a small script:

Code: Select all

ommandarray={}
if tonumber(otherdevices_svalues['Lux'])>1000 then print("on")
end
return commandarray

Again, I'm getting an error message:

lua: luxswitch.lua:2: attempt to index global 'otherdevices_svalues' (a nil value)
stack traceback:
luxswitch.lua:2: in main chunk
[C]: ?

Here is my Lux device:

Lux.png (33.78 KiB) Viewed 14716 times

Perhaps I'm missing something. I'm not a coding expert, sorry.

[Westcott]

What happens if you try -
print(otherdevices_svalues['Lux'])
Also check its value in Setup->More options->Events->Show Current States
Is it the only device called Lux?

[stefanvn]

Still not working....I'm getting a bit frustrated. Seems to me that I'm missing something obvious or something.

What I did sofar:

* Check value in Setup->More options->Events->Show Current States: Value is present.
* Check whether it is the only device called "Lux": it is.
* print(otherdevices_svalues['Lux']): same error message (attempt to index global 'otherdevices_svalues' (a nil value)).
* Removed Lux device and re-created a new dummy Lux device: Device gets updated with Luxvalue, but print(otherdevices_svalues['Lux']) still gives the same error message.

Seems to me that it shouldn't be that hard to retrieve such a value, but apparently it is too difficult for me

I would love to get some more hints and tips, in order to get this working.

[alexsh1]

I have setup everything and it all works just fine.
However, my only concern is that the azimuth and altitude are measured in degrees and I have km (I have used virtual visibility). I browsed through all the virtual sensors and was not able to find one corresponding to degrees and minutes.

[stefanvn]

Hi Alexsh1,

Thanks for your reply. Please note that the script that jmleglise provided is working perfectly! It is just that I can't seem to get other scripts going to switch lights on and off based on the Lux value calculated in the script. Hence my request for help in this topic.

[alexsh1]

Hi Alexsh1,

Thanks for your reply. Please note that the script that jmleglise provided is working perfectly! It is just that I can't seem to get other scripts going to switch lights on and off based on the Lux value calculated in the script. Hence my request for help in this topic.

Hi,

I never said that the script is not working. All I am saying is that I have the sun azimuth/altitude displayed in km and it should be in degrees. I was not to able a virtual sensor displaying degrees.

Cheers
Alex

[paulD]

Hi Alex,

You should vote for this suggestion :
http://www.domoticz.com/forum/viewtopic ... 31&t=10078 to encourage developpers to create a free counter (degrees and everything else).

[latis]

Hi,
I got an error message with this script.
Error: EventSystem: /home/pi/domoticz/scripts/lua/script_time_SolarSensor.lua:64: attempt to index field 'current_observation' (a nil value)

Why do I get this?

//Latis

[jmleglise]

Hi,

What is your line 64 ?

And did you read all the script at least once to made all the adaptation mentioned in the comments ? for example, as you are on RPi, you must change this line :
--json = (loadfile "/home/pi/domoticz/scripts/lua/JSON.lua")() -- For Linux