Well, I have done absolutely no theoretical computations. I just know  
what  computed during a week of working outdoors here building that  
garden for my wife. I loosened bolts of the mounts and tracked one by  
moving it every 15 minutes or sooo. I also draw on the real life  
experiences of other off-gridders with whom I have associated.  The  
best figures I have seen show 12% increase. When I first got into  
this none of them promised better than 10%.

I did some looking around in the last few and now I am seeing a  
number of different sources quoting 25-40% increase. I don't know  
what these new trackers are promising and what they are actual  
delivering. I really haven't paid much attention to it in the last  
three four years. Zomeworks references an article by Dick Perez from  
Home Power magazine (<http://www.zomeworks.com/solar/trackrack/ 
Homepower_june2004.pdf>). Richard is pretty good and he usually has  
his ducks all in a row before he opens his mouth so I would think  
there's some good info there.

I still feel that the application of money to solar PV should go into  
more panels rather than tracking technology except in the most  
moderate of climates in the high sun regions. Murphy just loves  
adverse weather conditions. I am a 1600 feet on the western slope of  
Mount Mansfield where it can get as cold as -45F, November and  
December brings windstorms that gust 80 mph ( every year we see gusts  
over 100 mph anywhere from two to a dozen times ) if someone can find  
me an automatic tracker that will stand up to all that, I will give  
it a whirl.


On Aug 21, 2006, at 6:25 PM, Olin Lathrop wrote:

> Brian Riley wrote:
>> Sadly not even close to true.  The accepted figure for tracker gain
>> is 10% tops.
>
> That doesn't add up mathematically.  Unless I've really screwed up the
> integrals (quite possible since I'm supposed to be getting home and am
> rushed), it seems up to 57% gain is possible.  That assumes that  
> sunlight is
> the same strength and available for a whole 180 degrees and the  
> tracker is
> kept flat on to the sun as apposed to a fixed midday orientation.   
> I know
> the effective sunlight will be less in the morning and evening as  
> it passes
> thru more atmosphere, but still optimum daily tracking versus fixed  
> midday
> but at proper height should be better than 10%.
>
> I'm always immediately skeptical when someone quotes "accepted  
> figures" or
> "everyone knows" without justification or the test conditions  
> carefully
> spelled out.  Often these general wisdoms are true for a certain  
> set of
> conditions lost in time, and then get applied lots of places where the
> assumptions aren't valid.
>

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