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

[Reuben K. Caron]

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].

How does the solar window in those places compare to that in Gaza?  
What is the website you use to check such things?

The over voltage condition only occurs during heavy solar conditions,  
right? So non-heavy days it works fine?

Can you define "heavy solar condition?"


> 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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> Power at lists.laptop.org
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