Hybrid Car – More Fun with Less Gas

Weather station - sunshine? - Page 2

register ::  Login Password  :: Lost Password?
Posted by daestrom on May 11, 2004, 9:38 pm
 


An even easier method is just hook a DMM up as a current meter and read the
current output of a small PV cell such as those sold in hobby electronics.
The DMM will pretty much read the short-circuit current of the cell and
that's pretty linear with solar insolance.  No op-amp and power supply
required.

daestrom



Posted by Duane C. Johnson on May 12, 2004, 2:12 am
 
Hi daestrom;

daestrom wrote:

I agree.


That's true.

I have used a Radio Shack DMM with an RS-232
output. See:
http://www.radioshack.com/searchsku.asp?find"-812

Although if you are using a data logger that measures
voltage one needs to convert the cell current into
voltage. I use a Dataq instruments data logger. See:
http://www.dataq.com/194.htm  only $4.95

Another option is a data logger that can read mV.
Then use a small valued resistor.


    Home of the $5 Solar Tracker      Receiver
   http://www.redrok.com/electron.htm#led3X  [*]
  Powered by             \  \     \        //|
 Thermonuclear   Solar Energy from the Sun / |
Energy (the SUN)           \  \     \  /  /  |
Red Rock Energy             \  \     /   /   |
Duane C. Johnson   Designer  \  \  /  \ /    |
1825 Florence St  Heliostat,Control,& Mounts |
White Bear Lake, Minnesota    === \   / \    |
USA      55110-3364                ===   \   |
(651)426-4766        use Courier New Font \  |
redrok@redrok.com     (my email: address)  \ |
http://www.redrok.com   (Web site)          ===

Posted by Alec Chiasson on May 23, 2004, 10:15 pm
 Hi all;

I am intrigued by this thread as I am reminded of the TMY2
simulations that Nick did awhile back(wherein I bemoaned the fact that
there is little Canadian equivalent to US insolation data). If the
Solarium Workbooks which date from 1981 were either no longer valid or
destroyed, I have an RS-232-ported DMM from Radio Shack, with accompanying
software for logging (do I need the data logger?) and am wondering:

a) For how long the Edmund Scientific ( from whom I got my telescope...the
Astroscan 2001, in uh, 1980 or so...even says not to look at the sun
through it! ) photodiode ( or whomever sells it cheapest ) should be
utilized for useful data

b) If I could simply use US data from say, Maine at similar latitude

c) What's this about the NRC of Canada/Fahrenheit 451??

Alec

On Tue, 11 May 2004 21:12:10 +0000, Duane C. Johnson wrote:



Posted by Duane C. Johnson on May 24, 2004, 2:44 am
 Hi Alec;



RET Screen used to have good Canadian data:
http://www.retscreen.net
However, they completely changed the web site
and I can't find the info anymore.

This site also has data:
http://eosweb.larc.nasa.gov/cgi-bin/sse/sse.cgi?na+s01#s01
Then "Enter latitude and longitude ".


Here's a beautiful relay that is very useful in a data logger
project. BTW, the description is in error. The coil is actually
110 ohms and run well on 24V.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item817592421


That's a bit dangerous as weather varies greatly over different
longitudes.

Duane


    Home of the $5 Solar Tracker      Receiver
   http://www.redrok.com/electron.htm#led3X  [*]
  Powered by             \  \     \        //|
 Thermonuclear   Solar Energy from the Sun / |
Energy (the SUN)           \  \     \  /  /  |
Red Rock Energy             \  \     /   /   |
Duane C. Johnson   Designer  \  \  /  \ /    |
1825 Florence St  Heliostat,Control,& Mounts |
White Bear Lake, Minnesota    === \   / \    |
USA      55110-3364                ===   \   |
(651)426-4766        use Courier New Font \  |
redrok@redrok.com     (my email: address)  \ |
http://www.redrok.com   (Web site)          ===

Posted by nicksanspam on May 25, 2004, 1:38 pm
 

I recall some SBSE (Society of Building Science Educators) talk about
computer programs that generate TMY files from other weather data files.
I don't think they were cheap or easy to use. You might ask NRC about them.

Another approach to solar house heating simulation is to find the long-
term worst-case month for solar house heating in the sense of the minimum
ratio of solar energy that falls on a south wall on an average day divided
by the indoor-outdoor temperature difference. The Solarium Workbook says
a south wall in Halifax gets an average 2341 Wh/m^2 on an average -3 C
Jan day and 1650 (523 Btu/ft^2) on an average -1 (30 F) Dec day, and
2341/(20-(-3)) = 102 and 1650/(20-(-1)) = 79, so December looks like
the worst-case month.

Then you might toss a die (or two coins) and reckon 1-2 is a cloudy day
(0 Wh/m^2), 3-4 is an average day (1650 Wh/m^2), and 5-6 is a clear day
(2x1650 Wh/m^2) and record the amount of backup fuel the house would need
after a long series of coin flips. To save time, you might start by
calculating the amount of stored heat the house would have after a long
string of average days. An overglazed direct gain solar house that works
well on an average day can shoot itself in the foot over a few cloudy days.


NREL used 30 years, 1961-1990 :-) Then again, things may have changed
with global warming.


NREL only lists Caribou (too cold) and Portland, which is sunnier and
colder than Halifax, with 940 Btu/ft^2 on a south wall on an average
26.6 F December day. You might use a Portland TMY2 file and add 30-26.6
degrees and reduce the sun by a factor of 523/940...
 

I've heard this story from two people who were deeply involved. It seems
that some part of the Canadian government worried that this 1981 Solarium
program was becoming so popular that people might need a lot less government
help with their energy problems, so they cancelled the program at Brace
Research Institute at McGill U at Ste. Anne de Belle Vue near Montreal and
ordered Brace to stop printing the workbooks and ordered all existing copies
in English and French destroyed. You might still find one in a library.

I have a copy that was rescued from a loading dock by one of these people,
who managed to carry away a car trunkful before the rest were destroyed :-)
With further investigation (a lot of talking with people in Ottowa), this
might make an interesting muckraking magazine or newspaper story. Let me
know if you'd like more details...

Nick

Tired of Iraq? Do something about it. Learn to halve your energy use
while having fun with math and science.

Join solar guru Steve Baer and PE Drew Gillett and PhD Rich Komp and
me for an all-day workshop on solar house heating and natural cooling
strategies ("HVAC Nonsense") on July 9 in Portland, OR--see page 25 of
http://www.ases.org/conferences/2004_call_for_papers/SOLAR2004_prelim_program.pdf


This Thread
Bookmark this thread:
 
 
 
 
 
 
  •  
  • Subject
  • Author
  • Date
please rate this thread