Estimating GHI or DNI from DHI or diffuse component of POA?

[Will Hobbs]

Has anyone looked at estimating unshaded irradiance from a shaded measurement?

For example, what if a pyranometer in the field gets shade from a nearby object, while the PV array is mostly unshaded, and you wanted to work backwards to estimate unshaded GHI or POA?

I'm thinking that this probably can't work well, but thought it was worth asking the community. I suspect it won't work because, in the case of what is actually a clear period, diffuse irradiance will be relatively low, but it could also be low because it is heavily overcast...

Will

[Will Hobbs]

Thanks, Adam and Anton. 

That’s what I figured. At least it’s good to know I was not missing something. 

On Tue, Feb 10, 2026 at 2:03 PM Adam R. Jensen <adam...@hotmail.com> wrote:

If you have PV power you could probably estimate whether it is very overcast or clearsky. 

If it's clearsky, then you can get pretty decent DNI from CAMS.

But it does seem kinda messy..

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From: pvlib-...@googlegroups.com <pvlib-...@googlegroups.com> on behalf of Will Hobbs <will....@gmail.com>
Sent: Tuesday, February 10, 2026 12:36:49 PM
To: pvlib-python <pvlib-...@googlegroups.com>
Subject: Estimating GHI or DNI from DHI or diffuse component of POA?

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