[RE-wrenches] Solar Boost Controller in Senegal

Sat Jun 27 16:28:40 PDT 2009

Hello again,

Thanks to all of you who chimed in with suggestions and comments on this
very apparent mis-application of the Solar Boost charge controller!!  

In looking at options for them, I thought of using the Morningstar 15Amp
MPPT controller.  They have a cut-off of 70V DC on the Voc, and ask for an
array not to exceed 400 watts.  The system here in Senegal is a whole lot
closer to meeting those criteria than the Solar Boost.  (73Voc and 440
Watts/p)  I have written to MS to see what they think about this.  

I hope to hear from Solar Boost to see their opinion, on what the best plan
of action could be from their perspective.  Chances are, Solar Boost has no
idea the equipment was used this way.

Some of you asked who designed this?  I am not really sure, but there is a
company named Earthwalk that primarily provides laptop computer packages for
remote education facilities.  They come with a battery charger cart for the
laptop batteries that is designed to plug in at night (especially when there
are problems with the grid power during the day.)  The Earthwalk company
provides as an "accessory" a solar charging station for locations without
the grid.  They include the system I described, but with a few other unusual
design thoughts.  (They use AGM batteries instead of GEL batteries, they
have a new DR1524 inverter, and they use a  Solar Converter Model VCS-2AH
switch, that I think is being used as a Low Voltage Disconnect, and I think
that is set at 20V....)  These systems were assembled very nicely into a
rolling cart in the states, and shipped to Senegal.  (The 12V Dekkas are
measuring 5V now, on this end before placing into commission.)

So - it is likely that Earthwalk commissioned a "solar" company to build
this for them.  I am trying to find that out now.

I just want to recommend the best action to them now instead of when all of
the systems start failing...which I am afraid they will do very soon.  I see
enough failed systems.  I would just like to stop this train wreck.

Thanks again for all your input.

>From the bush in Senegal!!

Walt

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Larry
Crutcher, Starlight Solar
Sent: Saturday, June 27, 2009 7:42 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal

...And the Voc is present every morning before the current is high  
enough to start the controller. That's when I would expect to have a  
problem. boB, I doubt that the Voc sample duration is long enough to  
cause a problem.

I know that Rick got back on this list a few months ago so if you  
(Rick) have any input to help Walt, we welcome your comments.

Larry Crutcher

On Jun 27, 2009, at 2:35 AM, boB Gudgel wrote:

> Wind-sun.com wrote:
>> Yes, it is a poor design. though you may not have any problems  
>> there with the heat de-rating of the panels. If the panel  
>> temperature gets under about 40C you may blow out the input. As  
>> long as you have a load on the output of the contgroller, it will  
>> keep the voltage down, but if the output is disconnected the input  
>> could go up to full voltage.
>
> Remember that this controller opens up every so often, (8 seconds or  
> so?) to check Voc and adjust the MPP-V based on that measurement.
>
> boB
>
>
>
>
>> Who designed such a system?
>>
............................................................................
......................
>> Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
>> Online Store: http://store.solar-electric.com/
>> Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
>>
............................................................................
......................
>>
>>   ----- Original Message -----
>>   *From:* Walt Ratterman <mailto:wratterman at sunenergypower.com>
>>   *To:* 'RE-wrenches' <mailto:re-wrenches at lists.re-wrenches.org>
>>   *Sent:* Friday, June 26, 2009 3:22 PM
>>   *Subject:* [RE-wrenches] Solar Boost Controller in Senegal
>>
>>   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...
>

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