Yama Ploskonka wrote: > Hmm. John's words sounded as if y'all had already a particular model > picked up. I interpreted that from the "10 W" detail. I am still at > the stage of figuring out the cost/performance sweet spot. > > > 10W Solar panels will be deployed with the first > > laptops in areas without power. > > Price is a major concern for me. All over-the-counter laptop solar > options I've come across seem to be priced for "Shibumi" compradores or > UN field projects. :-( > > Hi Yama,
I don't have specs for the "official" OLPC solar panels, but I've been experimenting on my own. I have the red panel you've been using from HarborFreight (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44768) and its output is only 1.5W peak. I didn't get much luck with that one. Perhaps if we had two of those in parallel... I looked elsewhere and found Volkswagen panels (part # 1 CO 915 687 D) that cost me around $20 + shipping on E-Bay (YMMV). These are panels that VW attaches to its cars' windows before shipping them. The panels trickle charge the battery while the cars get transported. Apparently this helps with not having to deal with a dead battery and resetting the VW's onboard computer when the cars reach the dealership. The panel comes with charge controller that helps in preventing reverse flow of current. The connector on the panel is an OBDII (http://en.wikipedia.org/wiki/OBD-II#OBD-II) type, but can easily be replaced with anything else. I chose RCA type phono connectors on a whim and its paying off. See http://sameerverma.org/blog/?postid=171 for details. The older VW panels (silicon based) output 3.2 Watts at around 18 Volts but the newer ones (looks like thin film) do 4 watts at around 12 to 14 Volts. I've had much success with the newer one. I usually park my car on the upper deck at San Francisco State Univ. where my car gets much sunlight. I typically get 9Volts + at 8:30am and it keeps going until around 5pm. The voltage peaks around mid-day at 13.9 Volts. With this setup, I go from zero (or close to zero by running the laptop until it dies) to 20% approx in one day. About four days in a row, and I get 90% + charge. I have suspicions that the charging isn't linear, but I haven't logged any of this. A few days ago, I got a second panel and fitted it with the same RCA phono connector. Next, I bought a Y-connector from Radio Shack so that I could combine the power of both panels in parallel. These connectors are designed for audio, but they work well for what I am doing. Now, with two panels in parallel, I get 65%+ charge in one day! At peak, the panels should be spitting out 4 + 4 watts. On the other side of the equation, I also did some tests with a Kill-a-watt device to see what the XO will pull in in terms of wattage when charging, running, etc. I got: XO turned off, empty battery: 21 watts XO turned on, empty battery: 21 watts XO turned on, battery removed: 10 watts (stays fairly steady during boot up) XO turned on, battery removed, backlight turned off: 7 watts XO turned on, battery removed, backlight turned off, camera+mic on: 8 watts See more http://lists.laptop.org/pipermail/olpc-open/2008-March/000635.html In all, its been a terrific learning experience. If this is something that others find useful, I'll put it up on the wiki. cheers, Sameer -- Dr. Sameer Verma, Ph.D. Associate Professor of Information Systems San Francisco State University San Francisco CA 94132 USA http://verma.sfsu.edu/ http://opensource.sfsu.edu/ > If OLPC (also very price conscious :-)) does come across a specific > provider, let's hear! > > Thanks, > > Yama > > > > Martin Langhoff wrote: > > On Sat, May 3, 2008 at 11:46 AM, Yama Ploskonka <[EMAIL PROTECTED]> wrote: > >> What is the provenance of those panels and is there any publicly > >> available information on their performance re:XOs the rest of us > can use? > > > > I'm not sure which of the solar panels / blankets it is. There is > > really good infoin the wiki, but it's spread across several pages - > > the first 10 or so hits for > > http://www.google.com/search?q=site%3Alaptop.org%20solar%20panel are > > good > > > > > > > > > > > > martin > > > Martin Langhoff wrote: > >> On Sat, May 3, 2008 at 11:46 AM, Yama Ploskonka <[EMAIL PROTECTED]> wrote: >> >>> What is the provenance of those panels and is there any publicly >>> available information on their performance re:XOs the rest of us can use? >>> >> I'm not sure which of the solar panels / blankets it is. There is >> really good infoin the wiki, but it's spread across several pages - >> the first 10 or so hits for >> http://www.google.com/search?q=site%3Alaptop.org%20solar%20panel are >> good >> >> >> >> >> >> martin >> > _______________________________________________ > Server-devel mailing list > Server-devel@lists.laptop.org > http://lists.laptop.org/listinfo/server-devel > _______________________________________________ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
