Michele Oliosi

yes you got it, x = 2 (because half-cut) and y = 3 (# of strings)

Can you also share the voltec module references ?

The partition tool is not really adapted to this kind of situation either. For irregular shadings, it tends to overestimate the losses. I would suggest changing the parameter "Fraction for electrical effect" to about 20 %. This will reduce the electrical shading loss so that it has about the same magnitude as the jinko modules. I did not go as far as setting a 10% fraction because it is better to be very conservative in this case.

This is normal, since PR is defined normalized by the front-side POA irradiance (GlobInc) but bifacial modules can also capture light from the back. The PR of bifacial projects is oftentimes > 1. There are more details on this help page: https://www.pvsyst.com/help/performance_ratio.htm Regarding the negative Global Incident, this is also normal, because it accounts for the front side irradiance relative to the horizontal plane. If you just look at the front-side, there is more irradiance on a horizontal plane than on a vertical plane. This is of course more than compensated by the backside irradiance part of the loss diagram.

The Global incident will be negative if the orientation is worse than the horizontal fixed plane. I am not sure why, just from your text. Indeed, in principle, trackers should have a better transposition than a fixed plane. It is difficult to answer just from the loss diagram and 3D screenshots. Could you export your project and send it to support@pvsyst.com ?

Did you try other distances? I don't see a problem because you show just two instances. At 4 meters there may be still a lot of impact from mutual shadings.

In your top question, the shadings are not exactly the same. Are you using the fast (relying on interpolations, which are sensitive to tiny rounding differences) or slow method ?

EW trackers here can follow the sun closely in the morning and evening. Instead, fixed tilt does not have a good orientation in the morning and evening.

Hi, this is a complicated question. The partition model is really ill-fitted to this kind of arrangement. The best is to model this first with the module layout: In this situation (GCR, tilt, climate, inverter layout, type of modules) this gives me about 0.9% electrical shading losses. If I then wanted to replicate this in the partition model, it is best to proceed by trial and error. Here defining 3 partitions in Y and 1 partition in X seems to work best to replicate the same amount of electrical shading losses. I tried first Y = 6, but the electrical shading losses were too small. In summary, it is hard to define how to partition in this kind of situation, and it will depend a lot on many factors. It is best to check with a simplified layout in the module layout to make sure that the partitioning gives a good amount of losses.

Half-cut cell modules in portrait, strung in U (2TU) have: - Partitions in y = 2, partitions in x = 1 For wider tables which are 2 strings across (26 = 2*13) still strung in U: - Partitions in y = 2, partitions in x = 2 https://www.pvsyst.com/help/shadings_partitioninstrings.htm

Please read the highlighted tutorial..

Hi, First, please understand that the partition model is an approximation that is well-defined in the case of simple rows of tables or trackers, with topographies that are quite regular. In the case of other irregular situations, such as your figure 6 and the discussion about figure 4, the usual rules from the help page do not apply. You can choose to use the partition model differently than the intended partitioning, as you did, but this should be done very carefully. I think you are correct in decreasing the number of partitions when shadings are irregular; this is the more conservative approach. Regarding figures 3 and 5, I agree that a partition in X is missing. Indeed, it should be X = 2, to differentiate the different strings. We will correct these images asap. Regarding figure 1, I do not agree with your comment. Indeed, in the case of regular rows, the effects of by-pass diodes and diffuse fraction accounted together are best modeled by Y = 2. Even if there are multiple strings on a given MPPT, as long as they are all shaded in the same way, the effect is the same as having one string by MPPT.

This is not possible directly from a single PVsyst simulation (which is in hourly steps). But you can run multiple simulations to approximate sub-hourly results. In version 7.4.8 we added a tutorial for this procedure because it is a bit technical. You can find this tutorial here:

You have 1% "climate change" this parameter will make P50 and E_Grid(Sim.) differ. It represents the fact that the weather data used for the simulation is not representative for the P50 (e.g., the P50 may change in the future, or has changed since the data was recorded).