[RE-wrenches] Fwd: Charge control question

[Maverick Brown]

Try the SunSaver MPPT. It is 15A and be wired with Modbus and a display. 

Thank you,

Maverick


Maverick Brown
BSEET, NABCEP Certified Solar PV Installer ®
President & CEO
Maverick Solar Enterprises, Inc.
Office:     512-919-4493
Cell:        512-460-9825

Sent from an iPhone. 

On Oct 11, 2012, at 12:04 PM, Allan Sindelar <allan at positiveenergysolar.com> wrote:

> Wrenches,
> I'm posting this for Carl Bickford, prof emeritus of the renewable energy training program at San Juan College in Farmington, New Mexico. I'll forward your responses to him.
> I have a very interesting and talented friend who is rebuilding a blue-water sailboat for a round-the-world trip. He is well versed in solar and is trying to use a relatively large array to charge a big battery bank that will be used for propulsion as well as general electrical. The propulsion system will be backed up with a propane generator he is building himself out of a Toyota truck engine.
> 
> As you can imagine, there is no place on a sailboat where shading isn’t a problem. He and I were wondering if there were products out there that could MPPT either individual modules, or small groups of them for 12 V battery charging. I have seen such things for the inputs of grid-tied inverters, but nothing yet for off-grid. The other choice is to go with many small MPPT charge controllers like the ones from Solar Converters.
> 
> Any advice you can offer?
> 
> Take care,
> Carl 
> 
> Carl Bickford
> Professor of Engineering and Renewable Energy
> San Juan College
> 4601 College Blvd.
> Farmington, NM 87402
> 505-566-3503
> bickfordc at sanjuancollege.edu
> 
>  
> I offered the suggestion below. Certainly open to other and better ideas.
> Allan
> 
> I have not encountered this situation, so I have no advice from experience. At 12V, it's hardly an issue as it is with high voltage parallel strings, where a few shaded cells can cause a whole string to drop out of the inverter's MPPT. At most, a shaded cell weakens the output of that module. And since it's charging batteries, there's a greater amount of head room.
> 
> I would suggest looking into Blue Sky Energy's "i" series - smaller MPPT controllers that can be networked. We seldom use them, as our residential applications are different. But you could put a controller on a group of modules and network several together. One advantage, I think (you'd want to check this) is that Blue Sky's MPPT algorithm is analog, unlike Outback and others: on the old Solar Boost series, the MPPT boost was set with a trim pot to a particular voltage above battery voltage; the target is to set it to where the boost was greatest. You could set this boost slightly lower than peak, and output just a little below MPP. That way the overall output would be minimally reduced, and a modest amount of shading would not cause the shaded module to drop below collective MPP as readily.
> 
> Allan Sindelar
> Allan at positiveenergysolar.com
> NABCEP Certified Photovoltaic Installer
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder and Chief Technology Officer
> Positive Energy, Inc.
> 3209 Richards Lane (note new address)
> Santa Fe, New Mexico 87507
> 505 424-1112
> www.positiveenergysolar.com
> 
> 
> 
> 
> 
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