[RE-wrenches] Solar Boost Controller in Senegal

Darryl Thayer daryl_solar at yahoo.com
Sat Jun 27 19:12:47 PDT 2009


HI I am just asking for insight here, why do you say AGM instead of Gel aren't they the same horse different color?  

The same capacity, the same voltage temperature curve, both starved electrolyte, both have the problem that it is very difficult to tell the state of charge? 

Are gel or AGM better for very deep cycles, I thought the flooded Lead antimony were the best for many deep cycles, flooded lead calcium best for low discharge rate, long life on shallow cycles and less need for equalization. 
Daryl  

--- On Sat, 6/27/09, Walt Ratterman <wratterman at sunenergypower.com> wrote:

> From: Walt Ratterman <wratterman at sunenergypower.com>
> Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal
> To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Saturday, June 27, 2009, 6:28 PM
> 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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