[RE-wrenches] Solar Boost Controller in Senegal

[Allan Sindelar]

I didn't say it's an incorrect use. Please reread what I wrote. I agree it's
one of its biggest advantages. 

 

But in Africa, once it fails it may be very hard to find a technician who
can determine what controller to replace it with if the SB50 fails. (They
aren't serviceable in the field, but must be shipped to Blue Sky, I
believe.) Maybe Phocos is widely available in Senegal, in which case it's a
better choice.

 

When the RVPP SB came out in late 1998, we didn't have many odd-cell-count
modules, so that wasn't recognized as an advantage. And those controllers
that sweep over a wide range to determine MPPT, such as the MX60, are much
better suited to matching odd-cell-count modules than the SB, which has a
limited adjustable boost range relative to battery voltage.

 

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

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Wind-sun.com
Sent: Tuesday, June 30, 2009 11:21 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal

 

Not sure why you think that cell matching is an incorrect use for MPPT. That
is one of it's biggest advantages.

 

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Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
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----- Original Message ----- 

From: Allan Sindelar <mailto:allan at positiveenergysolar.com>  

To: 'RE-wrenches' <mailto:re-wrenches at lists.re-wrenches.org>  

Cc: joeyh at earthwalk.com 

Sent: Tuesday, June 30, 2009 10:01 AM

Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal

 

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.

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