[esp-r] Re: PV modeling

[Liam O'Brien]

Thanks very much, Nick.  I finally got it working.

I have a follow-up question; this goes to anyone.  I've been analyzing the results and there's a bit of an inconsistency on a monthly basis.  In the summer months, the average efficiency (electrical output divided by incident radiation) that I calculated is several percentage points higher than the panels specs.  But in the winter months, it's very low (around 2%, vs. the 7% expected).  Looking closely, this seems to be caused by some arbitrary threshold of solar radiation (around 260 W/m^2), below which the PV produces no electricity.  So my horizontal PV panel produces little electricity even on a sunny winter day (lat=44N).   Any idea what might be causing this?  I'm using the Amorphous Watsun model.  Interestingly, the annual performance matches what I would expect; just not the monthly breakdown.   This could be a coincidence.  The same building model but with the simple PV model behaves exactly as expected. 

Thanks.

Liam

> Date: Wed, 27 Aug 2008 09:09:12 +0100
> From: nick at esru.strath.ac.uk
> To: obrien_liam at hotmail.com; esp-r at lists.strath.ac.uk
> Subject: [esp-r] Re: PV modeling
> 
> Liam,
>  
> To get round this problem you will need to have a fixed voltage node somewhere in your electrical network - without this the network cannot be solved. The simplest network I use for this type of problem is two node: 
>  
> 1. fixed voltage node (i.e. the grid)
>  
> 2. pv node
>  
> Connect both nodes together with a very low resitance cable and couple the PV panel or panels to the pv node  - this should work OK. 
>  
> Regards,
>  
> Nick Kelly on behalf of ESRU
> 
> ________________________________
> 
> From: esp-r-bounces at lists.strath.ac.uk on behalf of Liam O'Brien
> Sent: Wed 27/08/2008 04:48
> To: esp-r at lists.strath.ac.uk
> Subject: [esp-r] PV modeling
> 
> 
> Hello all,
> 
> I'm interested in modeling a PV panel only without the effects of network losses, an inverter, etc.  Ideally I would have liked to merely have a single node "network" that the PV panel is connected to.  However, ESP-r is not allowing me to do so, stating that "Error: Node   1 PV_node     is not connected to the network."  
> 
> Is there any way around this?  While I could model a more detailed network, the configurations I have tried consistently give me errors.  (Even if the "check network for errors" passed, bps quits without warning when I  try to initiate a simulation.  
> 
> Are there any good sources of information for modeling electrical networks?
> 
> Any advice would be greatly appreciated.  Thanks.
> 
> Liam
> 
> 
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