Trace original Modifications [RE-wrenches]

[R. Sparks Scott]

>Now in order to prevent the trace from charging from the grid, the
>suggestion is to lower the float to say 48 volts.

	Carl;

	There is one error in this logic, and that is assuming that lowering the
Trace float voltage will prevent it from charging the batteries. In grid
intertie mode, the Trace *is* the charge controller, so if you set it to 48
volts, that's what your batteries will float at even though the wind and
PV's are cranking amps into the battery bank. The excess current goes into
the grid.
	Additionally, the major loss of efficiency isn't the actual current going
into the batteries from the Trace, but the copper loss and eddy currents in
the three transformers in the SW inverter. My 1800 Ah,12 volt bank floats
just fine on 1½ amps, but the Trace consumes about 120 watts to produce
that trickle charge.

>Thinking maybe to put a batteryless
>inverter on the PV, and another inverter to keep a PVless battery on charge.

	Phil;

	I wouldn't go that far, but having one battery bank and two inverters is
the way to go. I have *no loads* connected to my SW, and use a smaller
inverter (an 812) to run the small appliances that I choose to power
directly from solar.
	Face it, in a grid intertie system, there is really no difference between
powering your household appliances from the battery bank and powering them
from the grid. If you power from the batteries, you sell less while the
consumption is replenished. If you power from the grid, your meter spins
the utility's direction, but the SW gets to spin it backwards more because
you didn't drain the batteries running loads. It's really a wash as long as
the grid is available.
	If you need backup power for grid failures, a transfer switch or 'wall of
receptacles' (in my case) can allow powering critical loads from battery
power, otherwise, let the grid do the work!

	-S

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