Re: [TRNSYS-users] about Type94

[David Bradley <bradley@tess-inc.com>]

Vito,

> working with PV system I observed there is perfect proportionality between 
> the number of PV panels and annual output of energy.
> I'm disconcerted, and the losses?

I would refer you to the technical description of the Type94 model. The 
equivalent circuit model behind Type94 does not include any losses that 
depend upon the size of the array such as wiring transmission losses. It 
simulates the performance of a single panel and then multiplies that 
performance by the number of modules present in the array.

> I have a grid connected PV system, I didn't add the load because it's not 
> important to my application, there is only the inverter (Type48) but Type 
> 94 ask an input, the third, that is the load voltage, in this case is it 
> the sum of the voltage of the PV models connected in series or is it a 
> particular value linked to the inverter (but the inverter brochure doesn't 
> give it)?

PVs tend to be either directly connected to a load or connected to a load 
through a maximum power point tracker. When directly connected to the load, 
the PV's operating point is determined by the point at which the current 
voltage characteristic of the load crosses the current voltage 
characteristic of the PV. With a maximum power point tracker in place, 
electronics essentially adjust the load seen by the PV so that the PV runs 
at its maximum power point. You will notice among the Type94 outputs that 
there are power, current and voltage at the maximum power point (which do 
not depend upon the load voltage entered as INPUT 3) and another set of 
power, current, and voltage, which do depend on the value of your load voltage.

Kind Regards,
  David

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