[RE-wrenches] Fwd: Charge control question

Mon Oct 15 14:52:11 PDT 2012

I was wondering about battery charging using Tigos.  I have a few spare Tigos and modules for them lying around and was thinking of using them with a magnum to run my radon fan and chest freezer. 

Since the Tigos have MPPT built in, would the use of a MPPTing charge controller be unnecessary?  If a person used a MPPTing CC what effects would that have on module performance?

Also I believe the Tigos need to communicate with the MMU unit to operate. 

Sent from my iPhone

On Oct 15, 2012, at 4:26 PM, Jay Peltz <jay at asis.com> wrote:

> Hi Allan
> 
> I have a client who did indeed install Tigo
> with a outback CC and it all works well
> 
> I don't recommend it for the boat. Too much to
> go wrong. 
> 
> Jay
> Peltz power
> 
> Sent from my iPhone
> 
> On Oct 15, 2012, at 12:46 PM, Allan Sindelar <allan at positiveenergysolar.com> wrote:
> 
>> Dan,
>> I checked out the Tigo website, and found nothing there to suggest that these were intended for off grid battery charging applications. A round-the-world sailboat is off grid. Are you suggesting that these will work in battery charging applications? If so,this is news. Do you have any more info you can share with us about this?
>> Thanks, Allan
>> 
>> 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 
>> 
>> On 10/11/2012 2:58 PM, dan at foxfire-energy.com wrote:
>>> Check out Tigo Optimizers:
>>> 
>>> http://www.tigoenergy.com/ 
>>> 
>>> db
>>> Dan Brown
>>> Foxfire Energy Corp.
>>> Renewable Energy Systems
>>> (802)-483-2564
>>> www.Foxfire-Energy.com
>>> NABCEP #092907-44
>>> 
>>> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan Sindelar
>>> Sent: Thursday, October 11, 2012 1:04 PM
>>> To: RE-wrenches
>>> Subject: [RE-wrenches] Fwd: Charge control question
>>>  
>>> 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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