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
[email protected] <mailto:[email protected]>
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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