Posted by Phillip on February 5, 2009, 4:46 pm
I live in California (San Fran area)
My electrical usage (kWh) per month is as follows:
1011 Average (24 month)
627 Minimun over the last 24 months
1458 Maximun over the same period
I have gotten 2 quotes for PV panels mounted to the roof and there were
between 35k and 40k.
So I have been doing some research. It looks like a very viable solution is
using 1 or more parabolic troughs, heating oil, to create flash steam and
then this would be powering a tesla turbine, which would then be attached to
a brushless AC generator
I have several issues that need to be resolved before I can start designing
Ideally, I would like to over produce during the day, and store in batteries
and also feed into the grid.
I would probably add the battery system in a later phase.
I need to find out how large of a system I would need.
I feel that if I spend a little more in the construction of the collector,
it would well pay for it self later on. I would probably create a first
layer mirror by having a polished piece of steel (4ftx8ft), silver plated.
The steel would be fairly thin and therefore easy to work with. I feel that
this would give me the highest effecienty. This would be using the lower
portion of the parabolic curve and thus being faily flat with a focal point
about 8"-12" above the bottom
This would be enclosed in a glass topped case with the focal point aimed at
the oil filled tube.
What I need to do is to try to figure out the size of generator that is
needed, how much power will be needed to produce the power I need, then
working backwards, figure out the size of turbine I should be using, and
then how many collectors I would need.
I know that there are general guidelines and formulas to figure this stuff,
but in all of my research, I have not been able to find this.
A few other peices of info I also need are where would be a good starting
point to have the plates for the turbine laser cut? I am feeling I probably
will be settling on a disk radia of about 10", but need to figure out how
many plates. from my research 10" will develope more HP at a lower RPM, yet
have more torque. Hard to start though...
I know I have asked ALOT, so if you can help with anypart, please let me
Posted by Morris Dovey on February 5, 2009, 5:17 pm
Although there are knowledgeable people here, you might do better to ask
about photovoltaics in news:alt.solar.photovoltaic
DeSoto, Iowa USA
Posted by azuredu on February 5, 2009, 7:01 pm
I highly recommend you to follow my design:
Home parabolic trough is not straightforward. Looks easy at first
sight, but there are many technical issues. There have been many
attempts, both DIY and industrial, but none has become a viable
product. Don't repeat the troubles already known to others.
And I am having private discussions with people along the line of your
ideas, as well as preparing industrial products. I maintain that a
commercial product will be available next year. If you are motivated
in engaging in the development experience, your participation will be
Otherwise, be a little bit patient, and you will get what you need.
Posted by Phillip on February 6, 2009, 12:37 am
Well... I like THIS design and thought a little better (maybe a little more
http://wims.unice.fr/xiao/collector.pdf (he he he!)
That is where I think I got some of my ideas. If I build one of these, I
would LIKE it to be as effient as possible.
A few things that I might alter is to have support ribs made out of foam and
coated with fiberglass and then sit the trough in here sitting on some close
cell foam tape.
Also, I may design the glass mounting so that it is "floating" but still air
tight. THis may help eliminate some distortions.
if using air, how many hG suction should I have in the glass tube and then
the trough? I may use nitrogen, as that should be pretty easy to find and it
is really safe to work with (besides displacing O2!)
Thanks for the hard work, putting it in public domain and also your input!
Posted by azuredu on February 6, 2009, 6:46 am
We have tried similar ideas to know that such things won't give you
high optical precision. Ribs and molds do work, but have high costs
and give only limited precision. Torsion bars as described in my new
documents are much better.
Depending on the mirror film you use, strict air tightness is often
not necessary. But the design should be kind of water tight, not
allowing rain water to enter into the box and leave traces on the
Filling the trough (nitrogen or so) does not seem to be necessary. A
half-tight box is enough. On the other hand, inside the glass tube it
is completely different. It depends on what temperature and what
efficiency you want to get, as well as what the means you get. Here
nitrogen is useless, and you should look for CO2, Argon, Krypton or
Xenon. How much can you get as vacuum level with your available tools?
Do you have means to evaporate getters?
The minimum needed is a small vacuum pump usually used by people
reparing air conditionning systems.