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PV Array (roof) - 52 Astropower AP-120 modules connected in 13
arrays of 4 panels each to give 48v 6.2 kW (DC), 5 kW AC. It is sized to give
6,900 kWH (kilo Watt-Hours) of energy a year (if shade free). We were
then consuming
9,500 to 10,000 kWH each year. Unfortunately we do have trees, and
they have grown in the years since we installed the system, so we are not
getting the energy that we used to from the sun. In the spring of 2009
the trees will be topped to eliminate the shading again.
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PV Combiner Boxes (garage)
- Three PCB-10 combiner boxes combine the 13 array outputs into three
circuits. Each array is individually fused at 15A. Two of the
combiners #1 & #3 combines 4 arrays, #2 combines 3.
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PV ground-fault protection (garage) - A Trace PVGFP
protects the system (and us) against the PV system having a fault. One
amp of ground current will trip off the three 100-amp circuit breakers, one
for each PV combiner.
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Battery Bank (garage) - 12 kWH of battery storage in one string of 4
maintenance-free12 V batteries in a battery box. The system
limits the discharge to 50% (6 kWH) to maximize battery life.
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Power Panel (garage) - One Trace 5548 inverter providing 5.5 kVA of
120 VAC power to selected loads in the house. The power panel also
contains the PV disconnects, battery disconnect, Grid Tie Interface (GTI),
and bypass switch.
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Grid Tie Interface (garage) - The Trace GTI connects the inverter to
the PG&E grid and assures that the inverter does not feed power back
into the grid in times of an outage. This is called islanding and can
happen in a outage if the load on the grid is within the capability of the
inverter. Without the GTI the inverter would happily provide my
neighbors with power.
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Charge Controller (garage)
- Three Trace C-40 charge controllers take the output of the PV array (in
three circuits) connect the PV to the battery and assure the batteries will
not be overcharged.
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Autotransformers (garage) - One Trace T240 autotransformer takes the
120v output out of the power panel and converts it to 240v to drive the well
pump and a shared neutral
load (the dishwasher & disposal). The second Trace T240
autotransformer balances the output of the existing (really old) 3 kVA
generator and converts it to 120v to the second inverter input to supply
power in the event of a long outage without sun.
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Outdoor Disconnect (outside)
- This is a switch mounted outdoors so that PG&E can make sure that there
will be no power flowing out of my house into the lines they are working on.
It is a PG&E requirement that a visible, lockable disconnect be provided.
