[Power] Fwd: solar panels to gaza - any pitfalls?

[Ed McNierney]

power at laptop.org should work, and if you're reading this, it does.

	- Ed

On Feb 23, 2010, at 1:02 PM, Richard Smith wrote:

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