<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Feb 23, 2010, at 1:02 PM, Richard Smith wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>2nd try.. Needs to be <a href="mailto:power@lists.laptop.org">power@lists.laptop.org</a> not <a href="mailto:power@laptop.org">power@laptop.org</a><br><br>---------- Forwarded message ----------<br>From: Richard Smith <<a href="mailto:richard@laptop.org">richard@laptop.org</a>><br>Date: Tue, Feb 23, 2010 at 12:58 PM<br>Subject: Re: solar panels to gaza - any pitfalls?<br>To: Barbara Barry <<a href="mailto:barbara@laptop.org">barbara@laptop.org</a>><br>Cc: robert <<a href="mailto:robert@laptop.org">robert@laptop.org</a>>, "Reuben K. Caron" <<a href="mailto:reuben@laptop.org">reuben@laptop.org</a>>,<br><a href="mailto:power@laptop.org">power@laptop.org</a><br><br><br>On Tue, Feb 23, 2010 at 11:37 AM, Barbara Barry <barbara@laptop.org> wrote:<br><br><blockquote type="cite">hi richard,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">wad suggested i email you on solar (i guess i just make it before your new<br></blockquote><blockquote type="cite">power list).<br></blockquote><br>List made.. You get to be the 1st post. Not you are not subscribed so<br>any response will get moderated. I'll approve it and add you to the<br>"accepted" list but you won't get list email by default. Most of it<br>you probably don't care about. But you are welcome to subscribe if<br>you like.<br><br><blockquote type="cite">2100 solar panels are approved and about to be ordered for gaza.<br></blockquote><blockquote type="cite">every child who gets an xo laptop in the next few months (our first<br></blockquote><blockquote type="cite">distribution there) will get a solar panel, too.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">these are 1.0, g1g1 machines.<br></blockquote><blockquote type="cite">any pitfalls with solar panels that we need to be aware of and trouble shoot<br></blockquote><blockquote type="cite">before distribution?<br></blockquote><br>We have reports from South Africa, Kenya, and a few individuals that<br>in heavy solar conditions the over voltage circuit of XO-1 can get<br>tripped [1].<font class="Apple-style-span" color="#000000"><font class="Apple-style-span" color="#144FAE"><br></font></font></div></blockquote><div><br></div>How does the solar window in those places compare to that in Gaza? What is the website you use to check such things?</div><div><br></div><div>The over voltage condition only occurs during heavy solar conditions, right? So non-heavy days it works fine?</div><div><br></div><div>Can you define "heavy solar condition?"<br><div><br></div><br><blockquote type="cite"><div>But we also have a bunch of places where the panel is working fine.<br><br>I'm working with gold peak right now on a voltage limiter option but<br>its not ready yet. The samples I tested did not function correctly.<br><br>Unfortunately, there's not any good way to know in advance if the<br>panels are going to have problems or not. You have to take some to<br>the site and test.<br><br>If the the problem occurs then there's not much you can do with out<br>modifications to the XO-1 or some sort of additional circuitry in<br>line. You are left with covering parts of the PV panel to reduce its<br>output.<br><br>[1] Right now over-voltage is the prime suspect although an EC<br>charging code bug can't be ruled out. We have field reports of XO's<br>stopping mid charge. I have very little details other than "it dosen't<br>work" the commonality among all the reports is heavy sun.<br><br>What I have been able to reproduce here in Boston is the no-load<br>shutdown when the panel voltage is above 18V. The symptom is that you<br>plug up the panel to the XO in bright sun and nothing happens. The XO<br>is turning off the power before things get a chance to settle into<br>what would normally be a working charge. In this case if you cover<br>the PV panel connect it to the XO and then slowly expose it to the sun<br>it works.<br><br>--<br>Richard A. Smith<br><br><br><br>-- <br>Richard A. Smith<br>_______________________________________________<br>Power mailing list<br><a href="mailto:Power@lists.laptop.org">Power@lists.laptop.org</a><br>http://lists.laptop.org/listinfo/power<br></div></blockquote></div><br></body></html>