SW again [RE-wrenches]

[Steve Bell]

    Although this is slightly different than "Silent Sell" I thought I'd
share how I'm setting my SW up for more of a "LBX Sell".  I have a large PV
array and a large wind turbine both charging a large battery bank. I have a
SW5548 that is legally grid-tied.  I wanted to sell excess power back to the
grid, but not recharge the batteries from the grid. The inverter is "ON"
7/24.

    I installed a 60 amp mercury contactor (normally open) in the AC1 line.
The relay coil voltage is controlled by a 24-hour timer and Aux #9 relay
(normal open) of the SW. They are wired in series. Aux#9 is set to close
when battery voltage is 0.4 volts higher than the Sell (float) voltage. The
timer "turns on" 8 times a day, every 3 hours. If when the timer "turns on",
the battery voltage is 0.4 volts or more higher than the "Sell" voltage,
then Aux #9 closes and the 60-amp AC1 relay is engaged. The SW then "sells"
the excess power to the grid. After about 2.5 hours the timer "turns off"
and AC1 is disconnected. A half hour later the cycle starts again.

I keep the inverter Max Charge amps set to 2 amps to prevent any significant
grid-powered battery charging should the battery voltage try to drop below
the "Sell" voltage, during the 2.5 hour "ON" cycle.

Remember, once you are grid-tied and selling, your battery voltage should
never drop below that voltage. So I use the timer to create a power outage.
Then, if my loads are greater than my wind/PV charging, the battery voltage
will drop and AUX#9 will not let the AC1 relay engage during the next timer
cycle. This allows me to operate off my battery bank until the wind/PV has
recharged my batteries above the Sell voltage.

Last month put 170 kWh back onto the grid.

Also, it is my understand that Trace is suppose to be releasing a new
version of the SW software soon (claimed in November). We'll see what they
do to address this situation (and an onboard battery or non-volitile RAM to
hold the programming).

Steve Bell
SunWize Technologies
sebpv at stelle.net

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