On Tue, 2011-06-28 at 18:34 -0400, David Beierl wrote:

> I wouldn't be surprised if you could run the turbine
> right into the controller and not worry about switching
> (I also wouldn't be surprised if you could not...).

Depends on the type of controller. An MPPT type controller ekes more
current out of solar panels than a less-expensive controller because the
MPPT controller will continually adjust the load it presents to the
panels to maximize panel efficiency (panels are typically more efficient
when running around 16 - 17 volts) while outputting lower voltage and
more current to the battery than the panels are putting out. I typically
see 4 or so amps going into the controller (at a higher voltage) and 5
to 6 amps coming out. Watts in = watts out, but different
voltage/current levels. It's kind of an impedance-matching device.

It pauses every couple seconds to adjust itself as needed to keep the
panels at their maximum output.

This might cause a collision of worlds if a turbine is connected to this
type of controller. Two active circuits fighting each other. The
controller would be changing the load presented to the turbine, looking
for maximum power, but the turbine, trying to drive a battery but seeing
the load change, would continually adjust its output.

Sounds like a fun science project, to see what would happen, but I leave
that as an exercise for the student. Safer to put in a switch. Depending
on how ugly this collision of two worlds might be,

My guess is, that as a load, other controller types will also confuse
the wind turbine's electronics. They expect to see a battery load.

I, myself, might be tempted to mount two sets of inputs: one for the
panels, one for the turbine, to avoid a chance that the turbine might
accidentally be connected to the charge controller. There should be no
problem connecting their outputs together.

I mean, look: when you're camped out in the woods waiting for a zombie
infestation to burn itself out, the last thing you need is a smoked
charge controller or wind turbine.

-- RJS