The optimum pitch value

[Mohamed1298]

Could you please clarify how to calculate the optimum pitch of single axial trucker of horizontal axis N-S project?

[Bruno Wittmer]

The pitch of the trackers has no optimum point in terms of energy yield. The shading losses will always decrease as you increase the pitch.

Therefore the optimal pitch is the result of a financial optimization, that takes into account the decreasing gain with the associated system and land costs that increase if you move to larger spacing.

You can use the 'economic evaluation' in PVsyst to set up a financial model that includes al the expenses and costs. Then you can use the 'batch mode' or the 'optimization tool' to find minimal values for LCOE (levelized cost of electricity) or maximal values for NPV (net present value) or ROI (return on investment).

These tools are describred in the corresponding help pages of PVsyst.

[Mohamed1298]

So may I know what are the losses out of the project performance which shall be affected by changing the pitch for the same capacity other than the near shadow losses?

Thanks

[André Mermoud]

In a fixed planes system (sheds), the only effects of the pitch is the mutual shadings, i.e. the shading calculations.

In tracking systems with backtracking strategy, the pitch also acts on the tracker's orientation when operating in backtracking mode (i.e. in the morning and evening).

[Mohamed1298]

i am using manual calculation to get the PR value and when i compare it with the software it was not matching so i just need you kind explanation about how the PR is calculated in the software to find the difference reasons. or you could please clarify why there is a difference between the below methods cases:

1. Irradinace is 2229 KWh/m2 

2. Appling the losses over the irradiance ( 2229* (100%+22.6%)*(100%-0.4%)*(100%-2.02%)*(100%-0.14)*(100%-0.7%)*(100%+0.52%)*(100%+10.72%)=2534.68KWh/m2)

3. looking to the software here in the below attachment it is coming =  2659 kWh/m².

[André Mermoud]

I don't know how you did your calculation.

In EXCEL, we calculate:

[Mohamed1298]

So could you please clarify how the other part of the bifacial is calculated on Excel?

[Mohamed1298]

Also may I know how you simulate the bificial modules in the PVsyst?

[Mohamed1298]

For the shading losses,is it possible to calculate the shading losses by equations or it needs 3D simulation?

For the utility scale plant which will have high voltage transformers, how we could calculate the losses in that transformer?

How to estimate the plant Aux. Losses?

[Mohamed1298]

When the plant has different transformers, we have to generate through the inverters reaction power so the inverter capacity will be increased to cover the reactive power of the plant after the inverter.

Should we mention the revised inverter capacity in the system design through the simulation process or we just mention the inverter based on the active power only??

[André Mermoud]

Many questions in a single péost ...

Bifacial: I don't see well what you mean by the "calculation in EXCEL". 

The bifacial model calculation is fully described in the help  " Project design > Bifacial Systems"

The bifacial feature of the PV modules is described by the only parameter "Bifaciality factor", which is the STC performance of the rear side with respect to the STC performance of the front side.

Shading calculations: except with the "Unlimited sheds" option, which uses an analytic calculation in 2D, the shadings calculations require indeed the 3D construction. 

The Transformer losses may be calculated from the transformer's datasheets parameeters, or generic loss factores for the Copper and the Iron losses.  See the help  "Project design > Array and system losses > External transformer losses"

The auxiliaries losses  represent the consumption of auxiliary devices (like cooler, computers, tracker motors, etc) that you want to be "deduced" from your sold electricity in the final balance.

PReactive power losses:  in the present time, PVsyst doesn't take the impedance (reactive "energy" loss) of the AC circuit and transformers into account. Therefore the power factor defined at the inverter output is the power factor as required by the grid manager.