Topic: Max potential solar radiation

[Jáchym]

Hi guys,

I have been trying to find a formula for calculating the maximum potential solar radiation.

I think it is based on your latitude and the day of the year. But I was unable to find any equation to do it. Does anyone know an equation that calculates this? It should give a number in W/m2 (or kW/m2). I know the absolute max should be 1440.

[saratogaWX]

How about this topic which cites

http://www.ecy.wa.gov/programs/eap/models.html Solrad VBS/Excel calculator

[Jáchym]

Hi Ken,
this is exactly the only source I found The problem is that I dont see the equation... it is an Excel macro and I have Libre Office on my Lubuntu laptop and it failed to open it when I tried yesterday.

[saratogaWX]

How about the math from http://www.powerfromthesun.net/Book/chapter02/chapter02.html
or details from http://www.solar.udel.edu/ELEG620/02_Solar_radiation09.pdf
or maybe http://www.pveducation.org/pvcdrom/calculation-of-solar-insolation

Hope this helps..
I'm surprised there's not a CPAN perl package for this already ... that would be easy to translate to PHP.
There is one https://metacpan.org/pod/Insolation but it does a one-day calc.

[Jáchym]

Thanks Ken, I will look at it!

[saratogaWX]

One more..in a Visual Studio 2008-based (C code) solution:
http://www.codeproject.com/Articles/78486/Solar-Calculator-Calculate-Sunrise-Sunset-and-Maxi

[hankster]

That 1440 figure is for radiation that is arriving at the top of the atmosphere. The amount that is actually reaching the surface of the earth is around 1050. Wiki has some formulas that you might be able to use.

https://en.wikipedia.org/wiki/Solar_irradiance

[Jáchym]

That 1440 figure is for radiation that is arriving at the top of the atmosphere. The amount that is actually reaching the surface of the earth is around 1050. Wiki has some formulas that you might be able to use.

https://en.wikipedia.org/wiki/Solar_irradiance

Thanks, yes I know it is the "theoretical" maximum. Though I know that the stations often overestimate it, I did see numbers above 1300 measured by the Davis Pro here in Brno...

[mcrossley]

Thanks, yes I know it is the "theoretical" maximum. Though I know that the stations often overestimate it, I did see numbers above 1300 measured by the Davis Pro here in Brno...

Cloud reflection affects global sensors - sometimes quite markedly, for a 'true' reading from a sensor you need a cloudless day.

[hankster]

Yes, edge of cloud effects can be very dramatic for short periods of time with readings 20% or more higher than normal. It is caused by the sun being magnified by water droplets at the edge of the cloud.