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Night Owl's Shareware - PDSI-006 - Night Owl Corp (1990).iso
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GLOSSARY.DOC
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1991-11-03
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DEFINITIONS OF TERMS USED IN THE PV COMPARE PROGRAM
Useable Watt: a watt which charges the battery or is used by a load
connected to the battery or Maximum Power Tracker.
Useable watts must be calculated based on the parameters
of each particular system, and cannot be determined
from the module type alone.
Maximum Power Tracker:
Aka Maximum Power Point Tracker, MPPT, MPT. Forces the PV module
to operate at the knee of the I-V curve, thereby producing maximum
wattage.
I-V Curve: Current (I) vs. Voltage (V) curve for a particular PV module,
recorded at a specific temperature and irradiance. When a
PV module is short circuited, it produces maximum current at
almost zero voltage. When a PV module is in an open circuit,
it produces maximum voltage and zero current. The I-V curve
describes the voltage and current outputs that occur when
loading conditions are between open circuit and short circuit.
Note that output current decreases as output voltage rises -
thus increased voltage drop between the PV module and battery
decreases the PV module output current.
Array: a group of PV modules in series and/or parallel combination.
Module: a group of PV cells in series and/or parallel combination, usually
in a sealed, pre-wired unit.
Cell: an individual photovoltaic cell
Irradiance: Solar radiation (sunlight) received. Usually specified in
watts per meter squared. 1000 watts per meter squared is
essentially equivalent to unobscured sunlight at noon.
Voltage drop:
Voltage that can be measured across the component in question,
such as the wire connecting the PV array and battery. Wiring
voltage drop multiplied by the current flowing = power
dissipated ("wasted") as heat. However, in a battery
charging application, these watts would not have been produced
if the wiring resistance did not exist. Therefore, voltage drop
is not a direct measure of watts gained or lost by using a particular
wire gauge. Note that the PV array voltage operating point is
forced higher by any voltage drops between the array and battery.
I-V curve data must be used to determine which wire gauge will
be most cost effective for a particular system.
Cmf: Circular mil foot: in this program, a conductor one thousandth
of an inch in diameter, one foot long.
AWG: American Wire Gauge