Saturday, Apr 26, 2014 at 15:29
Mike,
A few misconceptions here. An MPPT controller takes the available voltage, draws sufficient current to load the panels down to their optimum power voltage, then converts that voltage down to what the battery requires. An MPPT controller doesn't discard the excess voltage - it effectively uses the energy it represents to generate extra amps. "There's many volts available to lose between those 2 figures" - No! In fact voltage losses between the panel and controller not only waste energy, they upset the operation of the controller. Losses are less critical on the panel side of the regulator, but best minimised anyway.
There are a few (very few) MPPT controllers around that will accept higher panel voltages, but most for 12V battery charging are intended to interface with panels that have an unloaded voltage of about 23-24 and a maximum power point at about 17-18 volts.
There are advantages in series connection, but also a there's a downside. The power output of series connected panels is governed by the panel with lowest output. So a bit of shading on one panel affects the power supplied by all panels. With a parallel connection that shading only affects the one panel.
Cheers
John | J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
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