About some questions about partition

[Horizon]

Dear sir or madam:

I have some questions about partition, I need your hlep!

First I am confuse about help page: https://www.pvsyst.com/help/shadings_partitioninstrings.htm

In my opinion：

(a) The Fig.1 should be like the Fig2, Nb. rectangles in height (Y) is 1, similarly, Nb. rectangles in height (Y) is also 1. Unless this string is separately connected to one MPPT of the inverter, any part of the string be shading, otherwise, any part of the string is obstructed and the power of the string will decrease rapidly. 

(b) The Fig.3 looks very unique, although I particularly understand the role of bypass diodes by-pass diodes. If objects like trees or buildings or mountain create shadow on tables,the shadow should be irregular, I think maybe the Fig.4 should be more reasonable.

(c)In my understanding,whether the Fig.5 applied on relatively flat ground with only front and rear obstruction? I have designed many moutain solar plants, the shadow on tables is irregular and it's not a gradual expansion in the Y direction, for example the Fig.6. Ahthough the half-cut moudule in solar plant, whether the Fig.4 is more conservative and realistic? 

These are just some of my opinions, maybe they are all wrong. I would greatly appreciate it if you could give me some comments to help me correct them. 

Your backing is incredibly valuable to me.

 

 

 

 

 

 

[Michele Oliosi]

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.

[Horizon]

1 hour ago, Michele Oliosi said:

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.

I can't thank you enough!