re: tracking houses
31 mar 1996
james fischer again condescends:
> the astute student would have asked about the wind.
perhaps you didn't see this at the end:
>with the right combination of strong and elastic ropes and
>mass and damping, vulnerability should not be a problem.
> a pv array (or a pc treehouse), if suspended by cables, would be
> thrown off by the wind.
true. but how much and how often? being thrown off by 10 degrees once
in a while may make little difference. this is a numerical question.
> even the commerical-grade tracking solar
> panel racks have problems with the wind. a pv panel acts like
> an airfoil. this is why successful pv installations have polar
> mounts (a "polar mount" is a pole that points at the north star
> for those who might not know the term), massive counterweights,
> and lots of concrete to anchor them. even then, the darned
> things tend to "drift" in the wind.
contrary to what you say, the ones that use motors tend to be more stable
this way, not less, than steve baer's passive trackers, which will steadily
point with an offset sun angle in a steady wind.
> a better approach (but using some electricity) is a "seeker"
> toy, which uses 5 (or more) cds cells, each at the bottom
> of a short tube. the cds cells should be arranged like this:
this is 50's technology, james. today people use ccd arrays and
microcomputers that know what time of day it is.
> i love junkyards!
we can tell.
> to be 100% honest, i would hold off on buying any solar panels
> for the next 2 years (unless you must have them now). i have
> been sent a small test sample of what will soon be the ultimate
> pv material:
> - you shingle the south side of your roof with it
> - you buy it in rolls
> - it is cheap - nearly as cheap as shingles in the
> sort of quantities that would be appropriate.
> when one can make one's entire roof into a solar panel, optimization
> hacks like "tracking" become a moot point.
yeah yeah yeah, the big pricethrough is "just around the corner..." or is it?
i wonder, given the email below, posted with pali's permission.
date: thu, 28 mar 1996 15:02:03 -0500
to: email@example.com (nick pine)
from: "dr. p. singh"
i have a couple of corrections to make to your statements about my
pv research and ovshinsky's panels. i am working on electroplated solar
cells on transparent substrates. the electroplating process is a low
temperature process (60 c) and so could potentially be used on plastic
substrates with a transparent conducting oxide (such as tin oxide or indium
tin oxide) as the transparent contact. this would allow potentially low cost
devices to be manufactured since the process and materials costs could both
be very low. the transparent substrate would also allow heat to pass through
so that the use of these devices in a hybrid electrical/thermal system would
be a great idea. it also makes a lot of sense to use these types of pv cells
in a hybrid solar collector with a heat exchanger because that would allow
the cells to operate a little more efficiently !! i will keep you informed
as to how the research is going but don't hold your breath - after all it is
research and may take a few years to get to a point before it is
in terms of ovshinsky's cells, these are amorphous silicon alloys
that are made by a plasma assisted chemical vapor deposition process. those
big chambers that you have seen that look like a newpaper press are in fact
evacuated chambers in which gases of sih4, geh4, ch4, ph3 (phosphine),
ash3(arsine) and b2h6 (diborane) flow. an rf plasma is used to break down
these gases and the silicon, germanium, carbon, hydrogen and dopant
components are driven to the stainless steel substrate by the capacitive dc
self-bias between anode and cathode capacitor plates. the multiple chambers
are used to deposit individual layers of a device that may have as many as
10-12 layers !! this is not an inherently cheap process in small scale
production (<10mw/yr.) and so the selling price of $4.50 a peak watt is
about the production price of these cells. (ussc is very secretive about its
books and so the exact production price is erally not known but solarex's
thin film division makes a similar product and they are selling the cells
for more than it costs to make them). as far as i am aware only the solarex
polycrystalline silicon cell division is making money as a solar cell
manufacturer and they are selling at about $3.50 a peak watt for large
orders. there is a joint venture between enron corp. and amoco (solarex's
parent company) to make a 10 mw/yr. thin film pv manufacturing facility in
virginia. until now the amorphous silicon community has said that the cost
of amorphous silicon pv will drop dramatically (down to less than $1/wp) if
they could take advantage of economies of scale and produce at least
10mwp/yr. enron has called their bluff and so let's see what happens !! keep
posted. in the meantime solarex's polycrystalline silicon cell division is
ramping up to increase their production capacity three-fold and siemens
solar (what used to be arco solar) is also increasing production. so there
is a growing market for pv but primarily for remote applications in
i agree that we should start any solar home design with trying to
meet the heating load of a house through good passive solar design (after
insulating the house as well as possible) and then look to fund pv to supply
the necessary but small electric load (if economically justified).
i'm still looking for students for solar home projects - i'll let
you know if i get any bites.