In article , "Joel Kolstad"
writes:

mike wrote:
I once read that it takes more energy to make, deliver, install a solar
panel than the total energy you get out of it over it's 20 year
lifetime. If that's true, (small scale PV) solar makes little sense
from an environmental standpoint.

My understanding is that improvements in the efficiency of the panels has no
longer made that true... although of course to some degree it depends on
where you end up installing the panels!

An easy way to determine whether or not the statement could be true is to
see whether or not the cost of the energy produced by the panel over its
life -- using regular market rates -- exceeds its cost. If so, obviously
the panel must be producing more energy than was requried to build it, since
all the labor and materials the manufacturer put into the panel weren't
free!

Actually, solar panels DO - under circumstances, but that seems
beside the point in this particular thread. We all get a migration
from the original thread question to automobile economy (!) and a
lot of polarized opinions. :-)

It seems that the higher the polarization level, the more they
become like electrolytic capacitors. Put them in the wrong way
and they blow up...

The original thread question (maybe) was about using solar
cells for battery charging. In that case there needs to be
identification with two major application areas:

1. The characteristics necessary to charge a particular battery.

2. The range of input voltage and current sufficient to operate
the charging circuit as obtained from solar cells.

Nobody seems to have addressed item (1) which would seem
to drive the whole task. Item (2) could have been satisfied with
actual measurements in a 48-hour time period, one day to set
it up, a second day to take the measurements, noting time of
day, cloud cover, etc.

Please excuse me for thinking linearly... :-)

Len Anderson
retired (from regular hours) electronic engineer person