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PostPosted: Mon Mar 25, 2013 6:41 pm 
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Joined: Mon Apr 16, 2012 7:29 pm
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For Soiling, Mismatch and Module quality losses:
In version 5:
The input parameters are specified as percentages by respect to the STC power (or Energy).
When in the results they are expressed as a percentage of the "previous" value (i.e. the energy remainimg just before applying this loss). Therefore the value as percentage is slightly higher.
In version 6:
The parameter specification is now directly defined as the percentage of the remaining energy at this stage. Therefore the parameter value and simulation results match.

Wiring losses:
The basic loss parameter is the resistance of the wiring, but the loss parameter may also be expressed as a loss percentage when running at STC.
Now the wiring loss goes with the square of the current (or the power): Ewirloss = Rw * I².

Therefore: if we admit for example a loss of 2% at STC (under 1000 W/m²), when running at half the power (under 500 W/m²), the relative loss will be 1% and under 250 W/m2 it will be 0.5%
The loss has to be evaluated at each simulation time step, and the cumulated loss over the year will be of the order of 50 to 60% of the specified value in % of STC (depending on climate).

Transfo iron loss:
The Iron loss is a permanent loss (as soon as the transformer is connected to the grid). It is a 24/24H loss (or eventually about half of this time if you switch OFF the line connexion by night).
Only the Ohmic part of the transfo loss is related to the yield, and obeys the rule described above.

Unavailability:
The parameters define an unavailability duration. The unavailabîlity periods (up to 5) may be specified, or you can ask for a random distribution.
Now a failure in winter or in summer, or by clear/covered day, of by night/day, will not have the same consequences on the production of course. Therefore the energy loss is not equal to specified duration.


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