AC
AC vs. DC
Amperes
Battery
Charge Controller
Conductor
DC
Deep Cycle
Electron
Fuses, Breakers and Service
Disconnects
Generator
Hertz
Inverter
Kilowatt-hour
Life Cycle Costing
Load
Meters
Mixing Sizes and Brands
of Modules
Modified Sine Wave
Module
Module Mounting
Parallel Connection
Parasitic or Ghost Loads
Photon
Photovoltaic
Power
Series Connection
Shading
Sine-Wave
System Voltage Selection: 12, 24 or 48 volts
Trackers
True Sine Wave
Volt
Watt
Watt-hour
AC
Alternating Current. An electrical current which alternates from
zero volts to a specific voltage (usually 120 or 240) a certain
number of times per second. The number of times is called hertz.
In the United States, Utility power is 120 volts AC, 60 hertz
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AC vs. DC
Generally, only small cabin systems and/or RV systems are DC.
Using an inverter will enable you to use your standard appliances
as well as standard house wiring. The exception to this rule is
for water pumping systems.
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Amperes
(amps)
The standard unit for measuring the strength of an electrical
current.
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Battery
A device for storing and generating electricity.
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Charge Controller
A device that goes in-line between the PV modules and the
battery bank to control the flow of electricity entering the batteries.
The purpose is to prevent over charging of the batteries and disconnect
the bank at night. Some controllers also disconnect the load from
the battery when the battery is empty.
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Conductor
A substance or medium which conducts electrical charge. Usually
wire.
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DC
Direct Current. A flow of electricity in one direction and of
substantially constant value.
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Deep Cycle
The class of battery that can be drawn down relatively deeply
without harm. (Not a standard car battery)
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Electron
A subatomic particle of energy charge.
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Fuses, Breakers
and Service Disconnects
Overcurrent protection
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Generator
Provides backup AC power
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Hertz
Hz. The frequency of electrical current described in cycles per
second. Appliances in the U.S. uses 60 Hz.
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Inverter
A device used to convert independent DC power into standard
household AC current.
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Kilowatt-hour
The unit of measurement
for 1,000 watts consumed over one hour.
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Life Cycle Costing
The cost of equipment occurs only once but the cost of operation
goes on for a lifetime. You should plan to invest in high quality,
high efficiency appliances as the higher cost will quickly be
offset by much lower needs for solar electric modules and batteries.
For example, you'll need only 20 to 25 percent of the modules
to run a high efficiency refrigerator as compared to a conventional
type.
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Load
A device which consumes power. Ex: lights and appliances.
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Meters
Provide energy production information from modules and storage
data from battery bank.
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Mixing Sizes and
Brands of Modules
When paralleling units of different amperage ratings, the output
of the solar array will be the sum of the combined averages. When
paralleling units of different voltages, the lower voltage units
will simply begin to taper off sooner as high battery voltage
is reached. When connecting dissimilar modules in series however,
the amperage will be approximately that of the weakest module.
When connecting modules in series then, they should be closely
matched.
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Modified sine-wave
Refers to the wave-form of an inverter whose power output is similar
to but not exactly the same as the wave-form of standard Utility
power. Resembles a stair-step pattern when viewed on an oscilloscope.
This type of wave-form will run most appliances, though it is
not "clean" enough to mix with the Utility grid in the
case of net-metering.
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Module
A solar electric panel. Generates electricity from sunlight.
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Module Mounting
Other than using a tracker, modules in a fixed position and facing
due south will produce the largest amount of poser (in the Northern
Hemisphere). Call us for your site declination. Annually optimized
tilt angle will be your winter season setting (generally latitude
plus 15 degrees). Summertime productions can be enhanced significantly
by lowering the angle to latitude minus 15 degrees.
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Parallel Connection
A connection between two or more energy providing devices which
results in the amperage increasing. The connection must be: positive
to positive or negative to negative.
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Parasitic or Ghost
Loads
i.e. cordless telephones, electric clocks, TV, VCR, answering
machine, ni-cad battery charges, appliances with built in clocks.
You can either accept the "ghost loads" that come with
these appliances and increase the size of your system to deal
with them, or install switches to turn the appliances on only
when needed. Eliminating these loads will permit your inverter
to revert to a no-load or idle mode where it uses very little
energy.
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Photon
A particle of light energy.
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Photovoltaic
Photo- light,
Voltaic- produces voltage. Means "Produces voltage from light"
Usually refers to solar cells or solar panels.
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Power
A measure of electrical "work"measured in watts or kilowatts
(KW).
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Series Connection
A connection between two or more energy providing devices which
results in the voltage increasing. The connection must be: positive
to negative.
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Shading
Modules are sensitive to shading and can be affected even by a
leafless tree branch. A shaded cell or cell portion becomes a
load and rather than producing, actually draws current. If shading
will occur, ask your solar professional about by-pass diodes.
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Sine-wave
Refers to the wave-form of an Alternating Current
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System Voltage Selection:
12, 24 or 48 volts
Only very small cabin and/or RV systems are generally 12 volts.
Since line losses are high, solar modules and loads cannot be
far from the battery bank.
We suggest 24 volt systems for all but very large systems. Line
loss is much lower and substantial inverters are available.
Conventional AC wiring throughout the house is compatible with
AC power from inverter.
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Trackers
Are trackers a good idea?
Generally not for home power systems. Trackers are practically
useless in the winter, just when your load may be greatest. A
fixed mount with a few extra modules is the more cost effective
choice and will eliminate moving parts and possible service problems.
Installation is also far easier with a fixed mount. - Water pumping
systems for livestock would be the exception and a tracker here
would be appropriate.
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True Sine-wave
Refers to the wave form of an inverter whose power output matches
the wave form of standard Utility power.
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Volt
The unit of
measure for the amount of electrical "pressure" that
causes electricity to flow through a conductor.
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Watt
the unit of measurement for electrical flow.
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Watt-hour
The unit of measurement for electrical power consumed over the
time period of one hour.
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