[RE-wrenches] Solar Magic

[David G Katz]

Don,
SolarMagic is an MPPT DC to DC converter that you put on every modules 
in a string where some of the modules are going to be shaded. You would 
only do this if there are other strings that had no shading. When a 
module (or two) in the string is (are) shaded, the SolarMagic devices on 
the modules that are _*not*_ shaded raise their output voltage and lower 
their current, keeping them individually at maximum power point so that 
this string has the same voltage as the non-shaded strings in the 
system, and is therefor matched the MPPT voltage of the string inverter. 
Typically, if you shade a module in a string, its voltage drops 
somewhere between 1/2 of its peak power voltage and all of its peak 
power voltage.  This can lower the string 20 to 40 volts.  If there are 
other non-shaded strings attached to the input of the same string 
inverter, the shaded string will try to rise in voltage to equal the 
non-shaded strings, causing the modules in the shaded string to each 
rise in voltage several volts, taking them off their maximum power 
point.  Because of the nature of the I-V curve of the modules, this may 
lower their output by 25% to 50%, lowering the power of that string bu 
more than 25%-50%.
SolarMagic would cause the string to only drop by the wattage of the 
shaded module, possible only 5% in a 20 module string.
I see the use of these devices making sense as a retrofit in a system 
that was installed by someone who did not understand how much loss there 
is in a shaded string that is in parallel with non-shaded strings.
Cheers,
David

David Katz

President

AEE Solar

1155 Redway Drive

P.O. Box 339

Redway, CA  95560

Tel (707) 825-1200

Fax (707) 825-1202

david at aeesolar.com <mailto:david at aeesolar.com>

www.aeesolar.com <http://www.aeesolar.com>


>  
> Ok, so I've read the pitch from the Manu, however not sure even if the 
> published specs for shade improvement are very convincing to me..
> Would one of my esteemed colleagues explain what it does and how it works.
>  
> Thanks, Don Loweburg 
>
> ------------------------------------------------------------------------
>
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