Fast vs Slow simulation and detailed electrical losses

[Konstantina]

Dear Andre,

regarding slow and fast simulation of a small system I got almost the same results. But in general slow simulation is more accurate because it omputes the full shading factor at every step, or not?

Also I can not understand the option Detailed Electrical Lossses. It is connected with the precise localization of each PV module of the system, so the user should design the system in the option Module Layout part? And then there shloud be a difference in the report results? I tried but nothing changed.

Thank you very much

[André Mermoud]

You are right: the "fast" calculation is done by interpolations in the shading factor table, and I introduced for the version 6 a "slow" simulation where the shading factor is computed explicitely at each step of the simulation.

This is a good news that both results are compatible of course... With some very "structured" shadow shemes like row-to-row shadings, there may be little biases with the table interpolation; this new calculation allows to evaluate the effect of this bias.

Now the objective of the "Module Layout" definition is to evaluate the electrical mismatch loss.

This has to be compared to the calculation "according to module strings", for which as soon as a module is hit by a shadow, it becomes electrically inactive.

Both calculation modes give rise to a second "electrical" shading loss contribution, which is mentioned in the array losses.

Comparing these losses for both calculation modes should allow to determine the "Fraction for electrical loss" involved in the calculation "according to modules strings", in order to get the same contribution.

But the calculation of the "linear" loss contribution - which corresponds to the irradiance deficit on the array - should be about the same.