> 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%.

There are several reasons why it isn't as much of a gain as you might
expect:

1. The covering over the solar panels is designed to collect the energy from
a wide range of angles. E.g. you don't see any real increase just from the
light striking head on rather than at an angle. The area being collected
does change of course.

2. The morning and evening sun are MUCH less powerful due to the increased
mass of air (and pollution, etc...) through which the light passes. There is
a lensing effect that accounts for the apparent increase of the diameter of
the sun or moon, and you feel the heat since the low frequency IR bends
nicely, but the high energy UV is just not there and that is what solar
panels (primarily) collect.

3. The actual range of angles is usually less than 180 due to surrounding
obstacles like hills, trees, buildings the slant of the roof, and so on.

4. In many areas, during at least part of the year, morning dew or fog must
burn off before anything at all gets in from the sun.

It might double the power during the early morning or evening, but that time
isn't much of the total day. The over all result is unlikely to be more than
10%. And very unlikely to be more than the cost of the tracker.

I would be happy to see figured to the contrary.

---
James.
 

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