[Greenbuilding] PV Tracking

[Haudy Kazemi]

I think this may be playing a role.  When most people use the power 
output calculators/estimators, they look at the annual production 
figures not the daily figures.  A tracker in a high latitude may make 
larger difference in the summer than in the winter because the arc of 
the sun is longer, starting in the northeast and ending in the 
northwest.  A fixed array in those conditions will self-shade in the 
early and late parts of the day.  This may the root of the daily 
difference between the reported performance difference between the 
tracked and non-tracked array.

Roughly speaking, with guesstimate example numbers (actual values could 
probably be obtained by digging into an appropriate calculator):
During summer, tracked array may outproduce the non-tracked array by the 
~40% reported in this discussion thread.
During spring/fall, tracked array may outproduce non-tracked array by 20%.
During winter, with a short arc, tracked array may outproduce 
non-tracked array by 5%.
On an annual basis the tracked array may only exceed the non-tracked 
array by ~20%, even it does better than that in the summer.

Perhaps someone can check this in a calculator?



On 8/3/2011 8:00 PM, Nick Pyner wrote:
> I just think nobody is taking the geography in to account.
> There are plenty of PV installations around here, but I have never 
> seen or heard of a tracking one. This is probably because there is no 
> point in them. The situation could  be quite different in the more 
> frigid parts of the world for two reasons.
> 1. Even in what is laughably called the banana belt of Canada, the 
> insolation is not that great, and the skies are not so clear, so you 
> would need to chase every watt you can find.
> 2. In the summer, the days are longer. Hence the practical window of 
> opportunity may be as much as an hour wider, but the hourly march of 
> the sun is the same.
> A tracking system helps in both cases, and this heathen would imagine 
> the more polar you get the more sense a tracker will make.
>
> Nick Pyner
>
> Dee Why   NSW
>
>     -----Original Message-----
>     *From:* greenbuilding-bounces at lists.bioenergylists.org
>     [mailto:greenbuilding-bounces at lists.bioenergylists.org]*On Behalf
>     Of *RT
>     *Sent:* Wednesday, 3 August 2011 2:59 PM
>
>     I told him that I had been telling people (this List) that his
>     single-axis tracking array had produced 40 and sometimes 44% more
>     than the Enphase fixed array and that you (the Listmembers) were
>     telling me that I was full of $#!+.
>
>     We both just shrugged our shoulders (as if to say "Nyeh! What can
>     you do about  unbelieving heathens ?")
>
>

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