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Missing Energy


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I am designing a stand alone PV system.

I ran a simulation and after checking the output excel file, i found out that while the battery SOC was in the range of 40-50% (i checked the SOC at the beginning and end of the interval as well as the average) during 1 hour interval, PVsyst shows that User energy is less than that required by the load. see below:

SOC Beg SOC End SOCmean E Avail E Load E User T LOL E Miss

25/12/1990 8:00 0.4962 0.5104 0.5033 13798 47820 0 1 47820

25/12/1990 9:00 0.5104 0.5341 0.5223 23320 47820 0 1 47820

25/12/1990 10:00 0.5341 0.5666 0.5503 31938 47820 0 1 47820

25/12/1990 11:00 0.5666 0.6123 0.5894 45374 47820 0 1 47820

25/12/1990 12:00 0.6123 0.6573 0.6348 44820 47820 0 1 47820

Why the the energy available from the array and the batteries in the table above did not go to the load although it is more than what required?

I realized also that while the missing power could occur for only few minutes in each hour, PVsyst multiplies the missing power by the whole hour which in this case would overestimate the results

Thank you



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For this example, please send me the whole project in order that I can analyze the situation (using "Files" / "Export whole projects" in the main menu).

You can send it to support@pvsyst.com.

For the second question: I don't think the simulation behaves as you describe.

During the hour of simulation, the battery voltage is evolving according to the energy balance. If a regulator threshold is met (regulator switching), then the part of hour is accumulated as such, and the simulation begins again from this instant according to the new regulation state. This is only possible once in the hour; however it is probably sufficient if the thresholds have been defined correctly (i.e. if the hysteresis is sufficient).

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