[RE-wrenches] Solar Boost Controller in Senegal

Kirpal Khalsa solarworks at gmail.com
Fri Jun 26 15:49:45 PDT 2009


Walt......i believe those controllers will give you an MPPT boost going from
24V nominal in which eqautes to 44Voc in to 12Vnominal out.....in this
scenario 57Voc max is sufficient.....
The sharp panels you mention series together will exceed the 57Voc and
"should" cause trouble for the charge controller.....when? probably varies
based on manufacturing batches.....
If the system is a 24V battery bank than it doesn't sound like you have a
good design and are just lucky that the controller hasn't burned up
yet......
If you can reconfigure the system to be a 12V battery bank you could craft a
nice system with both panels in parallel and all batteries in parallel and
even get the charge controller to give you some MPPT boost especially during
the cooler months.  That controller based on spec sheet doesn't handle above
24V nominal solar array strings......or roughly 44Voc at STC.....
good luck....

-- 
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com




On Fri, Jun 26, 2009 at 3:22 PM, Walt Ratterman <
wratterman at sunenergypower.com> wrote:

>  Hello,
>
>
>
> I am in a very remote part of Senegal, (near the Guinea  and Mali borders…)
> and I have come across some prefabricated “plug and play” American made
> systems installed for educational institutions.
>
>
>
> The systems use two Sharp panels that are 220Watts, 33.6 Voc, 29.2 Vmp,
> wired in series, using #10AWG home run wire from the panels back to the
> charge controller.
>
>
>
> Charge Controller is a Solar Boost 50.
>
>
>
> Batteries are Dekka AGM – two strings of 250AH, 12V batteries.  (four
> batteries total).
>
>
>
> My specific question is about the controller.  This is a 24V in / 24V out
> charge controller with MPPT.  I have not used this before, so I am not
> familiar with the details of operation.
>
>
>
> The data sheet that I downloaded says that the maximum open circuit voltage
> is 57 VDC.  But, this system is hitting the charge controller with two
> panels of 33.6 VDC wired in series for 73.2VDC.  So, why is the controller
> not fried, or what am I seeing wrong here.  I suppose with the panel
> temperature being elevated maybe 35 degrees above 25 degrees and a resulting
> 17.5% loss, coupled with some voltage drop, the system may actually be
> seeing less than the 57 volts.
>
>
>
> But…..isnt this a dangerous way to design a system?  (it will get cooler
> here ….)
>
>
>
> Or am I missing something?
>
>
>
> What would be the appropriate application here….
>
>
>
> Sorry, I cant do a lot of internet research from here – limited download
> capability on the satellite….
>
>
>
> Thanks!!
>
>
>
> Walt
>
>
>
> *Walt Ratterman*
>
> *SunEnergy Power International***
>
> * *
>
> 11 Laurel Lane South     Washougal, WA   98671
>
> (360)-837-3680   ▪   fax (360)-837-1315   ▪   Skype  Walt-Mobile
>
> wratterman at SunEPI.org   ▪   www.SunEPI.org <http://www.sunepi.org/>
>
>
>
>
>
>
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