I have measuring data of global radiation on a tilted surface (a solar collector surface). Now I need to do 2 things:
- split the tilted global radiation into its diffuse and beam parts
- calculate the same terms (diffuse + beam radiation) on a different surface (different tilt and/or azimuth angle)*
I was able to solve problem (1) by inverting a tilted radiation model (HDKR), and combining it with the Erbs model on the horizontal plane. In this way I get quite good results for diffuse and beam parts on the tilted surface. Problems near sunrise / sunset and numeric problems are all under control.
For problem(2) however, I failed. I mention problem (1) because I intended to use its solution as a basis for problem (2): I intended to take the diffuse + beam parts on the horizontal (an intermediate result of problem (1)), feed it into HDKR to calculate diffuse + beam on an arbitrary surface. Now, these steps do not work. From step (1), I do not get diffuse + beam horizontal at times where I need it for step 2. This is because due to the different orientation, sunrise / sunset / sun behind collector happen at different times compared to the original surface. This is why my approach to step (2) fails.
I do not know whether this is a very unusual problem? For us it would be really useful to solve problem (2). It would allow us to use radiation data from one solar energy installation to evaluate a nearby plant with possibly different orientation.
Are there any special models treating with this or a similar problem?
Any help is greatly appreciated! Thank you all!