Date:         Sun, 5 Aug 2007 17:08:52 -0400
Reply-To:     Bill Glenn <idahobill@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Bill Glenn <idahobill@GMAIL.COM>
Subject:      Re: Google Pages/Solar Energy

Michael,
I have utilized Google since its inception, but never bothered to look at
features other than e-mail; thanks for demonstrating Google Pages, you did
a nice job. One small note with regard to the last, summarizing paragraph
on the solar page.  You wrote: "...then get enough solar panel power to run
it all, based on your latitude (less sunlight at higher latitudes) and
expected hours per day of sunlight."

That statement may apply to the design for a fixed PV installation, on an
annualized basis, but I'm not so sure.  For a mobile installation, in the
northern hemisphere, during the summer months when most of us are camping,
the reverse is true.

At the equator, daylight and dark are each twelve hours in length,
year 'round.  On any given day in the northern hemisphere in summer, as one
moves north to higher latitudes, the day is progressively longer.  At 44
degrees north in Idaho, I enjoy a longer day than you do in Southern
California (at the time of the summer solstice around June 21st, it's light
here until 10 p.m.), and if one travels far enough to the north, well,
that's why it's called the land of the midnight sun, and for a certain
period of the summer, the sun does not set.

In summer, the higher the latitude, the greater the amount of sunlight,
simply due to the increased hours of sunlight.  If the solar panels are
properly oriented to the sun, I should think that the solar energy captured
will also be greater at higher latitudes, than at lower latitudes, all else
being equal, no?.  (Fixed panels on the top of the van, which cannot be
directly oriented to the low angle light of the higher latitudes, may
indeed incur some loss of capture, but the longer day at the higher
latitude may still result in more net energy captured than at lesser
latitude)

Of course, all else is seldom equal.  Dust or smoke in the atmosphere,
humidity, tree cover, and clouds will affect the amount of solar energy
available at any given place on any given day.  Dirty solar panels will
also reduce the capture of the available energy.

Michael, the central point of your message, which is to design for your
individual circumstances, remains valid.  And don't be too envious of my
longer days.  I pay for it around the winter solstice, when it's dark at 5
p.m., and my house is in the shade most of the day for about five weeks due
to mountains blocking the low-angle sunlight.

Bill