Shading and optimizers

[Michalis Angeli]

Hello i would like to ask in this case i use optimizers.
Which type of shading should I define in Use in Simulation; According to module strings or Detailed electrical calculation?
Thank you.
 

[Linda Thoren]

Dear Michalis Angeli,

Power optimizers are electronic devices, which aim to draw the maximum energy possible from the PV modules within an array (i.e. they try to ensure that each module is working at its MPP at any time). The benefit we can expect from Optimizers is the recovery of electrical mismatch losses.

Your choice comes down to what kind of configuration your system have and what level of detail you will construct in the 3D scene.

By choosing According to module strings, you will in the construction of the 3D scene, define a partition in module strings. This option will calculate a shading factor  "According to strings", representing a higher limit for electrical effects. The partition model for electrical shadings is an approximation that allows to compute electrical shading losses faster than with the detailed "Module Layout" mode. This approach works best in regular row-based systems.

By choosing Detailed electrical calculation (acc. To module layout) you have to start by specifying a detailed "Module layout" configuration, you can ask to compute the shadings according to detailed electrical losses. The Module Layout tool is aimed at the detailed calculation of the Electrical shadings mismatch loss. It requires a description of the position of each PV module in the 3D scene, and the module interconnection as strings according to the inverters defined in the "System" part.

Regards

[Michalis Angeli]

Thank for your answer. Furthermore i would like to ask something more. I am trying to simulate an installation (5 kW) with 2 orientations. I want to connect all pv panels in one string in one mppt input. I want to check the efficiency of my project using optimizers, in two tiled roof installation. If I uncehck use multiple mppts inputs the system warning about the inverter is strongly undersized.
Can you help me?

 

 

[Linda Thoren]

What I understand from your screen-shot, is that you have 2 orientations, one string in each orientation, both with 6 modules in series. The total Nominal PV power is 5kWp. In your configuration you have 2 inverters of 5kW, one for each orientation and thus it is strongly oversized. By mixing the two orientation (In the “Sub-array name and Orientation” box) and keep your entire PV Array as one sub-array with 6 modules in series in 2 strings, PVsyst allows you to use only one inverter for the two strings, see screen-shot below. You are though obliged to have one string per orientation.

 

[Michalis Angeli]

Hello, thank you for the answer. I tried your suggestion but i don't want to have 2 parallel strings, and each string to has 6 modules. I want to have 1 string with 12 modules (the first six panels has ohter orientation than the others six panels), however I want to have one string with 12 panels together. 
How can I define this?

[Michalis Angeli]

When I try to do that I descripes above, in this dialog. 

The system appear this error: 


How can I solve this?

Thank you.

[Linda Thoren]

Panels in different orientations will produce varying amounts of electricity at different times, reducing the overall output and efficiency of the solar array. Thus, in PVsyst you cannot simulate two orientations in one string. By defining only 1 string with 12 modules, PVsyst will simulate all the modules in one direction, leaving the other direction empty, see screenshot below. This is why you have 24m2 in one direction (Fields azimuth 90) and 0m2 in the other (Fields azimuth -90). You can define the average between the two orientations or apply the configuration suggested earlier.

 

[Michalis Angeli]

Good morning, 
I have that error. 

How can I solve that?

 

[Linda Thoren]

This is not an error, but the result of having only one string. Installing modules in two complete opposite orientations on the same string would result in a very suboptimal energy production, so therefor it is not implemented in PVsyst to preform such a simulation. To use the solution of power sharing with one inverter and two orientations you need to have two strings, or simulate an average of the two orientation.

[Michalis Angeli]

Okay thank you!

[Michalis Angeli]

Dear Linda,

In this case. I have 2 orientations. I use the Orient. Mixed #1 & #2. I have one inverter with 2 MPPT inputs. With option Nb. strings in parall.: 2. That it means, I have two strings parallel in one mppt input? 


I ask this because, in orient distrib., I have that.

And I am confused, because of the fact we can't to define pv modules in series with several orientations, in one string. 
How that is possible?
And how the option Orient mixed #1 & #2 work?

Thank you!

[Linda Thoren]

Dear Michalis,

You can configure your array in the way that is the most optimum for your scenario. PVsyst is a simulation software that will simulate the parameters you provide and the system's dimensions and setup are ultimately your responsibility. You can see how many strings, inverters and MPPT you have in your array in the summary to the right. By default, PVsyst will suggest one string per MPPT in your case.

Since you now have two strings, you correctly see in the orient distrib that you have an equally distribution of Inverter inputs in each orientation. In other words, the Inverter is evenly distributing power from both the east-facing and west-facing solar panels. This balance ensures that, for example, in the morning when only the east-facing panel is producing power, this string generates electricity while the west-facing one does not. Conversely, in the evening. However, if you were to combine these two orientations into a single string, the overall production would always be limited by the orientation with the lower power output. This would result in a suboptimal performance because the combined string's production would never reach its full potential due to the constraint imposed by the least productive orientation.

[Michalis Angeli]

Very well, that is unterstood I ask all of these because this period i am investigating the effect of optimizers in this point "combine these two orientations into a single string, the overall production would always be limited by the orientation with the lower power output" . But as I unterstand that not possible and accetable from pvsyst due "the combined string's production would never reach its full potential due to the constraint imposed by the least productive orientation"

And the mixed orientation means that i have the same inverter to mixed two orientation but not compine the orientations in one string, right?