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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hello Eric,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Actually, I think I have a lot of useful information to give you
regarding your questions. I am in the middle of the West Bank in Palestine and
cant go into a lot of details right now, but just as a quick note, I would
definitely follow US guidelines on the combiner boxes (on anything over two
strings), AND I would definitely use the LA302DC surge protection – on the
combiners as well.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Maybe we can get together off line, when I complete this work in
the West Bank. I should be home in Washington State on Tuesday or Wednesday
and maybe we can get together on the phone then.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Thanks,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Walt<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Walt Ratterman<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>SunEnergy Power International</span></b><b><span
style='font-size:10.0pt;color:#1F497D'><o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-size:10.0pt;color:#1F497D'><o:p> </o:p></span></b></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>11 Laurel Lane South Washougal, WA 98671<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>(360)-837-3680 ▪ fax (360)-837-1315 ▪ Skype Walt-Mobile<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><a href="mailto:wratterman@SunEPI.org">wratterman@SunEPI.org</a>
</span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'> </span><span style='font-size:8.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>▪ <a href="http://www.sunepi.org/">www.SunEPI.org</a><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:8.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Eric
Youngren<br>
<b>Sent:</b> Tuesday, December 15, 2009 4:02 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> [RE-wrenches] quality off-grid PV for Africa<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Howdy Wrenches,<br>
<br>
First off, thanks for all of the nuggets of wisdom I have gleaned from this
list over the years. You guys are great and I've learned important things
from you. <br>
<br>
I am building what I hope will become a value-adding distribution company to
export off-grid PV systems and equipment to Africa and other places in the
developing world. I want to help take the best practices and
experiences of the US off-grid industry to the people in the world that really
need it. The quality of most PV installations I have seen in Africa
is pretty bad. I have two 'whitepapers' on <a
href="http://solarnexusinternational.com">my website</a> that explain in more
detail what I mean. What I've seen is that the PV dealers and installers
over there have access to good quality modules, controllers and batteries but
they have to go to the local markets for their wire and BOS materials and most
of that is poor quality and/or not appropriate for DC current and
voltages. So our plan is to send complete system packages that will
include all the BOS the local installers will need to install high quality
systems that will be efficient, safe and durable. We will also
travel to give installer training workshops and possibly develop a 'certified
installer' type program for our Solar Nexus Systems that would enable dealers
to purchase materials 'a la carte' and do the system design and integration
themselves. <br>
<br>
I'm working out the design right now for an order of 30 small (by US standards)
systems (roughly 400 W of PV, 300 W inverter, 12V PWM charge/load control, our
SolarNexus power center, 400 AH VRLA battery) that will be installed on schools
in rural Tanzania to run lighting, fans and one or two computers. I
have some questions about best design, low cost high quality materials and
where to toe the NEC line and where its okay to ignore the US code requirements
in the name of cost efficiency and realistic risk assessment. <br>
<br>
Specifically, here are some of my questions:<br>
1. PV combiners - for 12V systems using 3 to 6 modules in
parallel -- I'm planning to use Midnite short TBB insulated busbars for
parallel combiner blocks, similar in application to the old-school PDB
terminal blocks but cheaper. I know the NEC would require
individual string fusing, but is that a concern AT ALL on 12V or 24V
systems? I have never seen a module short out and feed current into
a parallel string, but I think that's why the code requires individual string
fusing. Has anybody seen unfused PV combiners become a
problem for 12 and 24 Volt systems? What is the practical limit at
which it does make sense to require string circuit
protection? Is this a case where the NEC could be optional in
Africa? (trust me, any kind of PV combiner hardware is going to be better
than the 'twist and tape' methods they're using now)<br>
<br>
2. Meters - right now I'm planning to put Trimetrics on all of these
systems. Obviously this will require user education for the meter to
be helpful at all. But I feel that educated users can learn how to
understand an amp-hour meter and they need more than red, yellow and green
dummy lights to fully understand what is happening with their
system. Thoughts or comments on that one?<br>
<br>
3. Lightning protection - my kits will include ground rods and #6
bare stranded copper wire for solid array/rack grounding and bonding for the
entire system. To me that seems like the best defence against lightning,
but what about additional protection? Are Delta lighting arrestors worth
the money? Do they work? Put it at the PV
combiner or at the controller?<br>
<br>
Sorry for the long-winded post. I'd appreciate any thoughts y'all
might have on anything I've mentioned here, or anything else that comes to
mind. Thanks!<br>
<br>
best energy,<br>
Eric<br>
<br>
-- <br>
Eric Youngren<br>
NABCEP Certified Solar PV Installer <br>
Island Energy Systems, LLC<br>
dba Solar Nexus International<br>
PO Box 894<br>
1016 Discovery Way<br>
Eastsound, WA 98245<br>
(360) 376-6842<br>
<a href="http://www.solarnexusinternational.com">www.solarnexusinternational.com</a><br>
<a href="http://www.islandenergysystems.wordpress.com">www.islandenergysystems.wordpress.com</a><br>
<a href="http://www.solarempowerment.net">www.solarempowerment.net</a><o:p></o:p></p>
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