Unused energy maximum?

[KeithG]

Hi,

This isn't the most important question, but I'm curious..

I simulated a system that was oversized and I noticed that the input/output diagram did not plateau as expected, it continued in linearly. Is there a maximum % for the unused energy loss? It looks like unused energy (due to full battery) is capped at 50%?

Thanks

Keith

[André Mermoud]

There is no limitation on the energy loss of course.

In the daily I/O diagram, the plateau we see in battery systems corresponds to full battery periods, i.e. when the battery is full at the end of the previous day: in this case only the required daily load during 24H may be produced/used by the array.

Now in other circumstances, the battery may be empty at the beginning of the day. In these cases the solar array will yield the 24H load and also fill the battery, which corresponds to the points above.

[KeithG]

Hi,

Thank you for the quick response. I have created an example - it is a bit of an extreme example in that the array is heavily oversized. I expected the plateau would occur somewhere along the grey line (that I had added to the pic).

Also note - battery capacity and daily load = 26.9 kWh but the effective output of the array goes well above the grey line. EDIT: I have tried a non-default regulator and I witnessed a plateau as expected, perhaps the issue is related to ticking the 'default regulator' check box?

 

Kind regards

Keith

[André Mermoud]

On the I/O diagram, I can't read the variable you have put as y-axis. If it is the EArrMPP, it is not affected by the behavior of the system (i.e. the full battery).

However according to the loss diagram, the behavior of you system seems very strange. Please send your whole project (using "Files > Export project") to support@pvsyst.com