[TRNSYS-users] Type94a - multi array will be wrongly calculated

[David BRADLEY]

Olaf,
  I have used multiple instances of Type94 to compute the output of 
differently oriented PV arrays a number of times and have gotten good 
results so I suspect that there may be a problem in the way the model 
has been defined. One complexity of Type94 is that it has two power 
outputs; one that gives the power at the maximum power point (and 
therefore assumes that the array is equipped with a maximum power point 
tracking (MPPT) device) and another that gives the array power at a 
particular load voltage. This second output is used for direct-connected 
systems that do not have an MPPT and in this case, the load voltage is 
an input to the model. Make sure that you are looking at the maximum 
power point power when you compare the output of the three arrays; 
otherwise, the problem may be that the load voltage on the array is so 
low that the power output of the array is minimal no matter what its 
orientation.  If you are unable to find the solution then I would 
recommend that you send your project to your distributor for further 
assistance.
Best,
  David


On 1/8/2013 03:12, Olaf Scholz wrote:
>
> I created a PV collector field consisting of three fields (type 94a) 
> for 3 incident directions (east, south, west) all 94a- modules are 
> connected tot o a type109 weather generator. The total incident 
> radiation for the three directions seems to be calculated correctly 
> (output of type109 for three different surfaces). But the power output 
> of the PV modules seems to be always the same, which is not correct. 
> Do you have a solution for that ?
>
> It seems to be the used input variable in type 94a is always the same, 
> so that only the last value is used for the calculation.
>
> *Olaf*
>
>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

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