[aprssig] RE: Small Solar Panels

Jon Adams jon at jonadams.com
Mon Sep 5 16:24:18 CDT 2005

On small solar panels, the very best prices I have seen yet (new, in the
box) are at Harbor Freight on one of their sales. However, the ratings on
the box I suspect are for "deep space" conditions, not real-world. 
I own both the 1.5 and 5W panels purchased from HF. They're thin-flim
applied to a sheet of thin glass, not flexible, with a total of 31 strip
cells of which only 29 are fully exposed. Both panels are cut from the same
material, the 1.5W panels are about 22% of a 5W panel. Efficiency is low,
poor even for thin-film cells (standard thin-films should be around 5-10%).

Measured values in Phoenix AZ, clear, windless, low humidity day, sun at
noon Sept 5, panel normal to sun:

				1.5W			5W
Open Circuit Voltage	20.3v			19.7v
Short Circuit Current	104mA			0.42A
Maximum Power at Load	0.98w at 157ohms	3.78w at 44ohms
Dimensions (active)	3.8x11.6"		17.5x11.6"
Efficiency (1000w/m^2)	3.5%			2.9%
Sale price			$11.99		$39.99
Price per watt		$12.24		$10.57

Cooling with water does not particularly change measured figures (panel gets
way too hot to handle in full sun), though temperature should change output
somewhat. Maybe it's so inefficient that it doesn't much matter... Price per
watt sucks, as my Kyocera KC125 puts out about 115W and cost about $500
($4.34/W), but the cost of entry is much lower.

Jon N7UV

Message: 9
Date: Mon, 5 Sep 2005 05:46:33 -0400
From: "Keith Kotch" <kkotch at earthlink.net>
Subject: [aprssig] Solar Panels
To: "'TAPR APRS Mailing List'" <aprssig at lists.tapr.org>
Message-ID: <E1ECDYt-0001m6-WF at smtpauth06.mail.atl.earthlink.net>
Content-Type: text/plain;	charset="us-ascii"

I could be surprised but I'd venture to say your specs are way off for the
price you've stated.  Just surfing around doesn't yield many 12v panels
under $60 much less 5w or 10w.  Some of the better prices I've seen for new
panels are at Harbor Freight.

Keith, KF4BXT

-----Original Message-----
From: Chris Rose

I hate to plug or mention Walmart but they have a 1'
square panel not flexible under $60 but I forgot to
look at what its output was maybe 10 watts?  They also
had a smaller one that put out 5 watts that was about
1' long and about 4" wide for around $15.  If anyone
can find them please let me know how far off I am with
my figures.  I will go back tomorrow and write down
the statistics.

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