Hybrid Car – More Fun with Less Gas

Weather station - sunshine?

register ::  Login Password  :: Lost Password?
Posted by John W. Hall on May 10, 2004, 2:17 pm
 
I'm looking into setting up a weather station to record data for
planning solar thermal panels (& because it's an interesting project,
& a friend wants me to introduce him to microprocessors, 1-wire
sensors etc).

Some low-cost kits, e.g. AAG's 1-wire weather station:
http://www.aagelectronica.com/aag/index.html
measure wind speed & direction, and one can add instruments for
rainfall & some other criteria.

But I don't see any low-cost stations that measure hours of sunshine,
and I don't know what constitutes "sunshine" when it comes to
measuring/recording it. I suppose one needs to measure direct sunlight
if interested in concentrating collectors, or diffused for flat-panels
(my interest is primarily DHW pre-heating).

I could perhaps find a nearby weather station and get their data, but
we're close to the mountains here, and micro-climates vary
significantly over short distances.

Suggestions or comments welcomed.

I just remembered that a high school here is setting up some solar-PV
panels, and will contact them to see if/what they are measuring. The
school is about 25 km from our proposed solar site, but I might
consider doing a joint weather station project with them.

--
Cochrane, Alberta, Canada.
"Helping People Prosper in the Information Age"

Posted by Ecnerwal on May 10, 2004, 3:02 pm
 


I don't think the standard instruments for this are made in enough
volume to ever be low-cost. However, you could probably get a very
acceptable qualitative measurement by dumping a small PV cell into a
resistor and measuring the voltage across (or current through) the
resistor. If you have several channels available, you could put several
cell/resistor combinations in several different orientations
(horizontal/angled at latitiude/vertical - for vertical and angled, you
could also have South, and other directions (probably not a lot of point
in going too far off South for a solar application in the northern
hemisphere, but perhaps 22.5 and 45 degrees to East and West of South).
If you plan to track you could also put one on a tracker.

Voltage across the resistor should give you a pretty good idea of direct
.vs. diffuse radiation. You could probably process the data to strip
that information out without too much fuss.

--
Cats, Coffee, Chocolate...vices to live by

Posted by nicksanspam on May 10, 2004, 8:31 pm
 

You might want to measure W/m^2 or Wh/m^2-day.
You can do that with a "pyroheliometer" or a
calibrated photodiode. Edmund Scientific used to
sell photodiodes for about $ uncalibrated or
$0 with a NIST calibration certificate. The
solar intensity is proportional to the diode
current at 0 V, ie into a short.

Daystar (www.raydec.com/daystar) makes a $34
solar meter with a digital output. Kipp and Zonen
(www.kippzonen.com) and Eppley (www.eppleylab.com)
sell more expensive versions, up to about $0K.


The 1981 Solarium Workbook (which may be hard to
find since the National Research Council of Canada
ordered them all destroyed :-) says a south wall
in Lethbridge gets 2578 Wh/m^2 on an average -4 C
December day...

Nick


Posted by John W. Hall on May 10, 2004, 8:40 pm
 On 10 May 2004 16:31:04 -0400, nicksanspam@ece.villanova.edu wrote:


Thanks for the info, Nick.
Yup, southern Alberta seems to be the sun & wind capital of Canada.
It's also got LOTS of bullshit, from the cattle feedlots - that's
another interest.

--
Cochrane, Alberta, Canada.
"Helping People Prosper in the Information Age"

Posted by Duane C. Johnson on May 11, 2004, 3:30 am
 Hi John;

This is a nice circuit for using a small
solar cell as a pretty good insolation sensor.

It is quite linear. See:
http://www.redrok.com/images/pv-i2v.gif

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)          ===

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