TMY (PVGIS data) vs. actual year discrepancy (merra-2 data)

The Minute column in the SAM CSV weather file format is optional. If you leave it out, SAM's photovoltaic models assume the time stamp is at 30 minutes past the hour. Otherwise, you can use it to specify the minute for each time step.

Best regards,
Paul.

Thx. Paul -

now finally, my PV is installed and I want compare actual vs. simulation. My *.smw file looks something like this: So, what does that mean?

My understanding is that hourly data of SAM output (eg. for 10:00am) would then be at 10:11am local time (Central European based on ,1, in the header line), but not considering DST?

Is that a correct assumption? Thx. for your help! 

Stefan

Hi Stefan,

I would use the SAM CSV (.csv) file format for solar resource data in SAM rather than the .smw format, which is an old format we no longer use. You can find a description of the SAM CSV format in Help, under Weather Files, Weather File Formats.

Here's a quick way to convert data from the PVGIS website to the SAM CSV format:

1. Download the weather file from re.jrc.ec.europa.eu/pvg_tools/en/tools.html#TMY in the EPW format (not CSV).

2. Start SAM and create or open a solar project, and click Macros under the Simulate button.

3. Run the Solar Resource File Converter macro.

Note that there is also the EPW File Timestep Correction macro that may address the 11 minute offset issue you describe.

Best regards,
Paul.