Changing irradiance for a location

[Behzad]

Hi,

I am trying to get hourly data for system production under various irradiances, e.g. 500 W/m2, 600 W/m2 etc. These have to be for the same system and the same location. I was wondering how I could change this value and run the simulation.

Thanks.

[André Mermoud]

I really don't understand what you want to do.

- For analyzing the behaviour under different irradiance classes along the year, you can do an histogram (see for example in the results "Predefined graphs", "Incident irradiation distribution" or "Incident energy distribution").

- In hourly data you cand choose hours with a given POA Irradiance (for example 500 W/m2).

Now if you want to manipulate the input hourly data for getting specific values, you can do this in an EXCEL CSV file that you will import using "Import ASCII meteo files".

But be aware that if you specify for example an irradiance of 500 W/m2 (GHI):

- If the diffuse is null, the system will receive a beam of 500 W/m2 * cosi/cosHsol (where i = incidence angle, Hsol = sun's height )

- But the diffuse is never null, and the resulting irradiance on the array will be the result of the transposition model.

[Behzad]

Hi,

Thanks for your reply. Let me be a bit clearer. For example if I wan to change a temperature for a specific day, will I be able to do it? Because in the Excel file, the values are only monthly, not hourly or even daily.

Thanks

[André Mermoud]

This is a completely different question.

If you don't avail of measured hourly temperatures in your datafile, don't define a column with monthly values.

When temperature reading is not specified in the importing format protocol, at the execution of the importation the program will ask you for Monthly values (which you can take from another near site), and will generate hourly values using the usual model for synthetic hourly generation (see "What are Synthetic Hourly Data ?")