#1 June 27, 2013 12:37:00

morrisok
From: Sussex
Registered: 2011-11-09
Posts: 79
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Monitoring Solar Irradiance


Hi,


Was wondering if anyone was measuring the solar irrandiance at the same location as their solar panels?  I have been looking for a home weather station that can do that and automatically upload online at a reasonable price.  If you are measuring it, is it useful?


Thanks


Kevin 3.92KWp 12x 327W E20 SunPower panels Sunnyboy 4000 inverter, facing ~south, no shading issues. Location: Sussex, URN 131







Kevin

URN 131, 3.92KWp 12x 327W E20 SunPower panels Sunnyboy 4000 inverter, facing ~south, no shading issues. Location: Sussex, http://pvoutput.org/list.jsp?userid=12216

Edited morrisok (June 27, 2013 12:37:00)

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#2 June 28, 2013 11:40:00

dwilliams
Registered: 2011-11-09
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Monitoring Solar Irradiance


Hi, my PV has been installed for nearly 2 years and I set up a weather station about 2 weeks ago which has a UV sensor.  It's an Oregon Scientfic Anywhere Weather model LW301_UV.  Very simple set up and live data feeds to iOS or Android app or www.osanywhereweather.com.  On the app, which is free, you can create yourself a useraccount even if you do not have a weather station.  On the map you will then be able see all the stations around the UK and world.  Click on one to see the live data, mine is in Uckfield, East Sussex.  Is it useful ? … too early to tell really but interesting.  Hope that helps, David





Edited dwilliams (June 28, 2013 11:40:00)

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#3 July 3, 2013 20:39:00

daveh
Registered: 2011-11-09
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Monitoring Solar Irradiance


Kevin - follow the second link and you will see my Solar Irradiance values for this location. The weather station is the Vantage Pro II and includes the Solar Irradiance sensor (not UV) which reports the equivalent Solar in w/metre squared.


Software is ‘Weather Display’


I use an over simplification to establish my PV performance against the measured value. The sensor is at the back of the garden so not sitting with the panels. There is a good correlation between the two and certainly you can see the temperature effects. 


David - URN139


http://www.uptonmanor.eclipse.co.uk/weatherdisp/wdlindx.html


http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=IENGLAND45





Edited daveh (July 3, 2013 20:39:00)

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#4 July 7, 2013 01:22:00

maxberan
Registered: 2012-11-11
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Monitoring Solar Irradiance


I also use  a Ventage Pro which is mounted immediately adjacent to my panels. I wrote an article for Weather magazine on how to estimate solar irradiance from solar panel output. The relationship is quite tight (10% error) for monthly averages but not so good for less. The issue is that the slope of the panels amplifies the direct beam over what the radiometer receives so the relationship is sensitive to the proportion of time the sun shines. Only over a sufficiently long period does this average out. Overall I generate 12.5% of total irradiation at the inverter (after allowing for shading) which is compatible with a nominal 14.5% for the panels and further losses due to inverter, wiring and dust.


My panels total 10 sq m so typically one sees rather similar numbers from the inverter in W as from the radiometer in W/sq m. However early in a sunny morning one can see an amplification of 4 or 5 all down to the cosine effect (my panels are at 32 deg).


I was thinking of replacing the UV sensor on the Vantage Pro (it has both) with a second radiometer with a shade ring to measure the zenith radiation as a proxy for the all-sky fraction. However I reckon I can recognise periods when there is direct beam from the amplification.


Having a radiation measurement certainly adds to the interest of the panels for me.


Max


URN2175 


 





Edited maxberan (July 7, 2013 01:22:00)

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