Just a thought off the top of my head.
== 1 of 5 ==
Date: Tues, Mar 20 2007 1:38 am
From: "Joe Rich"
No, not a simple one, but if someone has the space, I have an idea for
a cheap drive - use rear differential from cars / trucks.
I have been thinking of this for awhile - should be able to drive
quite a large panel with relatively simple motors. Just a thought.
On Mar 19, 6:17 pm, "Tony Luck" <tony.l...@gmail.com> wrote:
> On 3/19/07, Joe Rich <RichMan...@gmail.com> wrote:
>> The result of their estimate for clear air atmospheric attenuation
>> our latitude at local noon on December 21 is 742 watts/m^2, or -2.6
>> dB; for June 21 it is 962 watts/m^2, or - 1.4 dB (having designed
>> budgets for satellites, I think in dB).
>> When one takes into account the cosine of the normal of the collector
>> and the sun angle, the losses throughout the day of a fixed collector
>> become quite high.
> A Google search for "insolation san francisco" turned up some daily
> insolation tables for a few years. Ignoring the bad values near the
> solstices (as presumably cloudy days) I saw around 183 around the
> winter solstice, and 636 around the summer solstice. So yes, the
> low sun angle during the winter is measurably very bad for solar
> I've seen repeated assertions on the internet that a tracking
Getting somewhat close to the perfect angle has pretty
good benefits ... cosine(25 degrees) is around 0.9, so you
can get 90% of the benefit, with extremely approximate
I've seen a few people on the internet with solar collectors
that they make occasional seasonal adjustments. When
Joe has his simulator s/w up and running perhaps he can
run some numbers for a system with a small number of
adjustments per year.
For a solar hot water collector, I'd need to see a really, really
cheap design for the *tracking* hardware though. Collectors
are cheap (compared with solar PV silicon) so in many cases
it might be simpler to just add to the surface area by adding
more collectors, rather than add the additional h/w. Perhaps
this might be worthwhile if you invest in a fancy evacuated
 and everything I've read says it isn't cost effective to make
tracking systems for PV either.