André Mermoud

In the DC circuit (array of strings), the total wire length is indeed the lenght of the whole loop (this si mentioned just below "Please specify the total wire length for each circuit. " For the AC circuit, this is the line length (distance between devices).

Probably you have defined your transformer by a generic relative loss, i.e. proportional to the transformer nominal power. And this nominal power - evaluated by PVsyst on the basis of the PNomPV at STC, or the PNomac (this is your choice in the Project's settings) - has been changed in your different runs. This should not arise if you define an explicit transformer from the datasheets, the nominal power of the transformer will always remain the manufacturer's value. In this case the "generic" relative values will be updated as a function of this real Transformer nominal power.

There may be new features in the version 8, which were not implemented in the version 7. Now for the modification of the Rshunt and Rserie values, this was a feature of the software which has been mpdified. In the version 7, when they were judged not quite correct, these values were updated to default ones. This is no more the case in the version 8.

The files created in the V8 cannot be used with the version 7.

You can add a battery in your database from scratch by using "Databases => Batteries => New". But you are strongly advised to choose a similar battery in the database, modify its parameters according to your own component datasheets, and save this as a new battery. For defining an hybrid system, you should choose the button "Storage" in the project's dialog, and probably choose the option "Self consumption" for your case.

No, in the present time PVsyst doesn't consider the charging of the battery from the grid.

Sorry, it is completely impossible that PVsyst changes these parameters by itself. Please carefully check that you are comparing the same variants. NB: You can always reload and install the old version 8.0.13 if necessary. Both versions may be used simultaneously.

This is quite normal as you have defined a grid limitation of 1 kW (for a system of 200 kWp, 180 kWac). You can notice that the apparent value is 79 kVah, to be compared to a global delivery to the user of 224 MWh, i.e. 0.04%. Please note that you have the opportunity of completely forbid the injection to the grid when you define the self-consumption:

Yes indeed, the battery model of PVsyst uses information which is not always present on the datasheets. Some datasheets are really very brief. When you have to define a battery by yourself, you are advised to start from an existing battery, and adjust the relevant variables (mainly technology, kind of battery, number of cells in series and parallel, internal resistance (check dafault), self-discharge (check default), lifetime (numbe of cycles), sizes and weight

You can find some data about the current and voltage degradation in the works, namely, of the TISO in Switzerland. For example in this publication: https://www.researchgate.net/publication/256080133_TISO_10_kW_30_years_experience_with_a_PV_plant

We obviously don't avail of detailed ageing data for a specified PV module. The average degradation rate itself is really not well defined. In the literature you can find a wide panel of values (0.3% to 1%/year). The PVsyst proposition of 0.4% seems a reasonable choice for usual modules. The specific mismatch effect due to ageing has been developed "theoretically" as a tool in PVsyst, without any experimental basis. We don't know any publication studying this problem in the literature. The hypotheses under this evaluation (Monte Carlo evaluation of the dispersion progress) are purely speculative. Therefore this model is obviously not able to take your particularity into account in a reliable way. You can probably take a lower value for the Isc/Vos RMS.

The PVsyst proposition doesn't take the maximum current into account. It is your job to check it in your final design. However the maximum current of a PV array is not well defined: the value corresponds to the STC (1000 W/m2), but if the inverter is specified for a given maximum current, it will limit the array current during operation, by displacing the operating point on the I/V curve. By the I don't see where you find that maximum current of 180 A. The manufacturer specifies 325 A in the PVsyst database: Your configuration of 15 strings of 25 modules of 650 Wp represents a PV power = 243 kW, i.e. a current of 238 A under 1020 V at STC.

Please remember that we are working in hourly values. And the thresholds according to the battery SOC may arise during the hour, so that the transition from an operating state to another one may arise during the hour. Therefore you can have a "Battery full" state at the beginning of the hour, and a discharge during the rest of the hour. However there is also a visual artefact because you are showing lines from the middle of hour to the middle of the next hour. In your first plot, at 13:30 you have unused energy, but no BESS discharge. At 14:30, you have BESS discharge, but no Unused energy. The intermediate lines don't have any meaning.

First of all, the inverter's behaviour with grid voltage deviations is very rarely described in the datasheets, and probably different for each inverter. By the way, PVsyst doesn't treat possible Grid voltage variations along the time. This is not part of the input variables, and we really don't see from which source we could evaluate it in prevision simulations.

I don't see what you mean by "some modules are overlapping". For filling your field, you can do that manually by the mouse. But you can possibly use the option "Attribution automatique" (you have many options for doing this), and than correct what seems not suited for you, by exchanging/dragging the string attributions with the mouse.