Support for sub hourly

[RAMVEA]

Hi,

Will there be any update in PVsyst to support Subhourly data, as Subhourly (10min/1min) Meteodata is available it will be great if we can get subhourly energy values.

[jammyc]

+1 from me

• It would be very helpful in anaylsis of measured data

• In many jurisdictions billing is half-hourly basis

• It would help with analysis where loads change frequently

• Multiple meteo data sources provide sub-hourly inputs and it's a shame to throw that out!

...etc

[dtarin]

+1

Sub-hourly clipping is missing from PVsyst estimates, which can be non-trivial

[johank]

... late to +1 but absolutely agree.

For modeling performance from built systems (with measured data), sub-hourly clipping losses can be very large.

For predictive models, you'd also need high-res meteo data. Not much available yet afaik, but looks to be coming more and more.

[Michele Oliosi]

Hi,

Thanks for the feedback. Since this would be a very big change, a complete sub-hourly simulation is not on the horizon yet. However:

• you can already import sub-hourly meteo data, and use it to perform a hourly simulation
• we are currently working on a solution allowing a partial use of the sub-hourly data to address clipping losses

As johank points out there are not that many data sources just yet.

[kjs55]

I think it would be a useful feature to allow the custom import and direct use (simulation) of measured weather data (without hourly averaging). I think it would be relatively straightforward to write a PVsyst wrapper where the data is preprocessed into several 8760s on the front end, run through the core PVsyst tool as normal, and then post-processed on the back end. Namely, 1-min. measurement data is split into (60) 8760 files, 5-min. data is split into (12) 8760 files, etc. on the front end. Then, normal PVsyst is run over a loop (60x or 12x, respectively), with the appropriate time shift for each run. Then, the resultant output files are recombined on the back end (back into a 1-min. or 5-min. data set, respectively). In other words, there are really no major changes to the core PVsyst tool needed in order to implement this feature to enable simulations of (at least) custom, imported subhourly measurement data. Thanks.

[itaisuez]

Chiming in here as another request for sub-hourly simulation, even a partial one as Michele O. of PVSyst suggests.  Misrepresented clipping losses can be high, especially in areas with frequent intermittent cloud cover (e.g. Texas).  @Michele Oliosi, can you please let us know when this "partial clipping loss" feature will be released?

[jammyc]

On 4/25/2022 at 11:23 AM, Michele Oliosi said:

As johank points out there are not that many data sources just yet.

There might not be many meteo data sources, but load metering data are often in half-hourly or higher resolution.

[Daniel]

On 4/25/2022 at 12:23 PM, Michele Oliosi said:

Hi,

Thanks for the feedback. Since this would be a very big change, a complete sub-hourly simulation is not on the horizon yet. However:

• you can already import sub-hourly meteo data, and use it to perform a hourly simulation
• we are currently working on a solution allowing a partial use of the sub-hourly data to address clipping losses

As johank points out there are not that many data sources just yet.

A bit late, but I don't agree with the point that there are not a lot of subhourly data. Today (and it was the case last year when this was posted) almost all satellite data providers have subhourly data (stallite images are now 5-30min).. One might even say that a lot of providers were forced to adapt to this limitation of PVsyst and provide hourly files...

A true simulation on a lower timestep would be a huge gain in precision / effort on our end... 

And naively, I don't understand the difficulty... a part from the thermal model that has inertia, all the other elements can be establish at whatever time step... I agree that the computing time would probably be 4 fold if one let us say wants to have 15min simulations... but I don't think this is a real problem.

[Michele Oliosi]

Thank you for your comments!

19 hours ago, Daniel said:

Today (and it was the case last year when this was posted) almost all satellite data providers have subhourly data (stallite images are now 5-30min).

Okay, thanks for the remark. We will then have to review again the different data sources and see what usable data we find. We'll see to keep up to date on this.
 

17 hours ago, Daniel said:

And naively, I don't understand the difficulty

Indeed physically it is not so complex (although one needs to be careful with a few models, for example the thermal one as you mention). But purely in terms of code we would have to change a lot of things.

As mentioned, we are actively working on the subject of subhourly clipping, since there are still few questions to be elucidated.

On 4/25/2022 at 12:23 PM, Michele Oliosi said:

we are currently working on a solution allowing a partial use of the sub-hourly data to address clipping losses

We will present further conlcusions of our studies at PVPMC2023, and the poster should be made available online. With these studies we are gaining a lot of new understanding that should also help in the longer term to transition to sub-hourly simulations, if necessary.