I could not find a “month to date average solar (w/m2) tag” in the custom tags file.
Is there such a tag? or does anyone know how to have that type of data created?
If it doesn’t exist, Brian could you possibly add that to averages/extremes tags in the future?
Hi
put this in the feature requests
Do I need to physically retype it in the other category or is there an easier way?
Thanks
May I ask what you hope to get from this average? Since the watts/m2value will inevitably be zero for many hours out of the average period I don’t see its utility.
Copy & Paste? #-o
A monthly running average would never be zero…except at midnight on the 1st until sunrise…then it would go up drastically…It would be reset at the beginning of the month…It would be interesting to see if the average increases over years for a given month…By the way, thanks to whomever moved this topic over for me…I didn’t know if the copy & paste would work on here or not…
What I meant is that the value that is being averaged is zero for about 50% of the period that’s being averaged, so the resulting average will be a very small number. I just don’t see the value of it :?
i do see nikos point…i.e the average is going to be much less than the max for the day…
i think that sunshine hours totals is giving you the data you want I would think
Or maybe something like watthours/m2, the solar power guys must have some standard measure of total received radiation.
so what is the best way to approach this then?
Looking at some publications e.g. this one (see the page 15, MONTHLY MEAN DAILY TOTALS graph) I think Watthours/m2 is the best measure, either monthly total, or daily average by month. Daily average by month would be probably be best because it would take the length of the month out of the equation.
I think daily average by month as well.
Though this is an old post, i still would be very interested in a tag that shows wh/m2 per day and per month. Users of solar arrays in my area could use this for checking the return of their solar-power setups.
There are a couple more users interested, As I was following a post on a dutch forum “Het Weer Actueel” and someone asked if an average solar output could be found in WD. I read this old thread and the possible solution given here (Wh/m2) looks great!
I hope Brian has got some time for this.
Thanks!
Gerhard Witteveen
www.weeropdeveluwe.nl
I had forgoten about this thread
So if each minute the current wm/2 value was added to a daily value then that value stored at the end of the day in a logfile and reset, would that be the way?
then to get the running total for the month, just add that total (and divide by 24*60) for each day?, or
The calculation is:
(w/m2 summed each minute) / (60*1000) = kilowatt-hours (kWh)
How you accumulate that is up to you, daily, monthly, annual would probably be most useful, and then they’ll probaby want averages and to be able to get past month/year numbers too.
OK, good
WD actually already logs the wm/2 value every minute in the xxxxvantagelog.txtn file
so the data is already available to sum up
I will work on adding a custom tag to show this total value
so,
monthtodate kwh
yeartodate kwh
then I guess past months totals (where the month and year is part of the custom tag)?
I have added
%yeartodatesolarhrs%…Year to date kwh (if you have solar sensor)
%monthtodatesolarhrs%…Month to date kwh (if you have solar sensor)
to a new .zip update, ready now
update, have added
%todaysolarhrs%
now also to a new .zip update
I have the following data:
972.2kwh…Year to date kwh (if you have solar sensor)
81.8kwh…Month to date kwh (if you have solar sensor)
0.0kwh…Today solar kwh (if you have solar sensor)
Does this mean ( for the year to date) if i had a 120 watt solar panel it would produce 972.2 x 120 116664 (116.664 KW) watts of power ??
cheers
No, that only means that if you have a panel od 1sq m with 100% efficiency that is mounted horizontally (as the values are related to flat surface of 1sqm2) you would be able to generate 972 kwh year to date.
In reality the efficiency is never 100%
And most important, your panel is seldom laying flat. So you need to calculate with the panel elevation and azimut orientation.
I did an excell table that has been calculating minute W/sqm2 from a custom log before the new tags were available and then making detailed calculation of a sun position at given moment with regard to panel orientation (for many days the sunrise and sunset position are more than 90 degrees so you calculation has to consier that there is no gain if sun strikes the rear panel side)… Very detailed, too complicated.
In practice I’ve seen companies working with monthly coefficient for particular elevation / orientation. That was what local solar company calculated on my panel project and showed to be on a safe side, ie. gains are little higher than what the design calculation showed.
That’s correct. It would be good to add “per meter squared” to the description of those tags.