Irradiance Model - FAQs

Irradiance Model - FAQs

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Commercial User GuideCommercial User Guide
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Frequently asked questions about Solcast Modelling

This page represents the most frequently asked questions that the Solcast modelling team receive. Questions about global horizontal irradiance, global tilted irradiance, direct horizontal irradiance, direct horizontal irradiance and why one value might be greater than another.

Frequently asked questions:

Why is my GHI value higher than GTI?

Why is my GHI value higher than DNI?

Why is DHI90 sometimes less than DHI10?

Does your GHI number mean an instantaneous value or an average value over a time period?

When do you stop updating your data?

What wavelength range is used for the calculation of GHI?

We can see that Solcast offers albedo as an output parameter. When we use the albedo parameter, is the value the same for the entire location? And what was the spatial granularity of the data on albedo?

Is the best way to calculate tilted irradiance by using a horizontal single axis tracker and frequently updating the backtracking angle?

We have noticed that the results of our solar generation is clipping during the middle of the day, so that the power does not always increase with the irradiance. Why does this occur?

How does solcast model albedo?

Why doesn't my long-term historical GHI match the TMY GHI average?