[RE-wrenches] Solar Boost Controller in Senegal

[Larry Crutcher, Starlight Solar]

Allan,

MPPT technology is for harvesting the most power possible from any  
voltage being produced above the battery voltage, not the difference  
between Voc and Vmp. Because of this, nearly every battery charging  
system will benefit  from MPPT chargers. The climate does not matter  
for properly designed systems. In a hot climate (like Yuma ;) ) you  
want a much higher operating voltage from the PV panels. There will  
still be a big advantage from MPPT. There are very few situations  
where I would recommend a non-MPPT controller anymore.

Concerning Blue Sky charge controller failures, I have sold and  
installed over 1000 BSE products at our retail store over the years  
and they have the LOWEST failure of any controllers we have sold. And,  
the customer service is second to no one else. I understand and agree  
with your opinion to have serviceable equipment in remote locations.   
The most reliable equipment should be considered first. I also believe  
that a project like the one Walt is dealing with should have included  
spare equipment as part of sale, and, of course, it should have been  
designed right.

I had a Phocos MPPT 100/20 in a test setup for 10 months when it  
failed. I can't even begin to talk about Outback problems unless I  
take my comments to the RE-bitching list. The BSE 3048 would be a good  
replacement controller because it has the same footprint as the SB50  
and will handle the high Voc.

Kindest Regards,

Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and Installation

Mailing Address (NO SHIPPING):
11881 S Fortuna Rd.
#210
Yuma, AZ 85367

Shipping and retail store (NO MAIL):
2998 Shari Ave
Yuma, AZ 85365



On Jun 30, 2009, at 12:01 PM, Allan Sindelar wrote:

> Walt,
> I would also offer that in a hot climate, MPPT in general is only  
> useful in a case where odd cell counts take the Vmp away from 24V  
> nominal specs. That is, MPPT was originally developed to harvest the  
> voltage headroom between Voc and Vmp, which was greatest in cold  
> ambient temperatures. There is little benefit to MPPT in a tropical  
> climate, unless it’s being used (incorrectly in this case) to adapt  
> a particular module with odd cell count.
>
> Walt, I would suggest that you consider pursuing replacing the  
> Sharps with any 12Vnom or 24Vnom module commonly in use there, and  
> then either keep the SB50 because it’s already there, or replace it  
> with the most reliable non-MPPT PWM controller you can bring in or  
> find in country. This maximizes the likelihood that the system can  
> be kept in operation even if the SB50s fail (and experience says  
> that some will in time) and the locals can’t get service or  
> replacement product. It seems to me that the SB50 is an  
> unnecessarily complex component for this application, and a standard  
> PWM replacement controller will match poorly and inefficiently to  
> the Sharps.
>
> FYI, I called Earthwalk and spoke with “Joey” there. I copied him on  
> Rick’s email, and got a read response. So Earthwalk is aware of this  
> situation, although Joey was a computer tech, not one of the “solar  
> experts”. If they have integrity, they’ll contact you and start  
> making arrangements to get this resolved. Perhaps they can wire you  
> the funds to purchase compatible modules locally?
>
> I have copied Joey on this message as well.
>
> Allan Sindelar
> Allan at positiveenergysolar.com
> NABCEP Certified Photovoltaic Installer
> EE98J Journeyman Electrician
> Positive Energy, Inc.
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> 505 424-1112
> www.positiveenergysolar.com

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