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PV ONLY makes sense when electricity is consumed
efficiently! |
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Consider an Energy Audit. |
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Consider energy efficiency when choosing or
building a home. |
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Use passive solar techniques to reduce power
requirements. |
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Insulation. |
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High Efficiency Appliances. |
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Window Treatment. |
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Roof Treatments. |
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Time of use rates. |
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Shade. |
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Architecture. |
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Grid-Tie. |
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Grid-Tie with Battery Backup. |
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Stand Alone. |
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What Do you need it to do ? |
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How much power do you need ? |
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What is the daily / yearly profile of power use? |
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What happens if the power (Utility or PV) system
fails ? |
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Can I run my Air Conditioner ? |
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How much does a Solar System Cost ? |
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What is the payback time ? |
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Can I spin my meter backwards ? |
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How do I get more Information ? |
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In principle yes, in practice it is not
economically (or in the case of keeping the AC on backup power —
environmentally) feasible. |
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If you use a line-tie system then the solar
power you generate will offset some of the power needed to run the AC. |
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Currently the installed cost is of the order of
$8 – $9 per (STC) Watt before incentives. |
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State and Federal tax credits are available. |
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Buy-downs, net metering (the Utility pays you
for only the net power they supply you with) etc. can in some states (CA)
reduce the cost to about $4 /W . |
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With a Solar PV system you are buying power at a
known fixed cost . |
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Payback can only be calculated by guessing
figures such as energy inflation rates, etc. |
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Again, using energy efficiently is the only way
to win in the long-term. |
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Ask home owners who have PV, they are normally
more than happy to explain their system and how to get one. |
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Call your Utility company. |
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Find a local PV dealer in the yellow pages |
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There are many good sources of general and
technical information on the Internet. |
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Check PV and systems manufactures sites on the
internet. |
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www.AZSolarCenter.com |
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Solar Today and
Home Power magazines, are the most widely available sources of
printed information on PV systems. Both have a wide range on information
and advertising. |
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Total independence from Utility power. |
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Provides all electric needs. |
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Large battery bank for night and cloudy days. |
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Consider a backup generator / inverter incase of
system failure. |
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Minimize Electricity Usage. |
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Choose appliances for energy use. |
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Use only Appliances that require Electricity! |
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Minimize “parasitic loads” – loads that are
ALWAYS on, but do not need to be: |
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VCR / Coffee maker clocks |
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Appliances in Stand-by mode |
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Propane refrigerators |
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Gas stove and dryers |
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Gas / passive water heating |
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Solar Array |
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Stand-Alone Inverter |
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Batteries |
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Battery Cutoff |
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Other (depends on inverter) |
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Provide all electrical power for off-grid home. |
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Solar may be used to pump water well if
available. |
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Care must be taken to correctly size and
maintain system. |
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Solar Water pumps. |
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Pool Pump. |
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Irrigation control. |
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Lighting. |
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Evaporative (swamp) Coolers. |
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Convert Sunlight to electricity |
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Solar Modules will be very similar for all
systems. |
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Larger modules are normally cheaper in terms of
$ per Watt. |
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Angle |
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Modules should be oriented to face the Sun. |
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Module Temperature |
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The Modules produce more power when cooler. |
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Aesthetics |
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The mounting and color of the modules can
sometimes be chosen to blend with the architecture. |
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Trackers |
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Tracking the Sun increases the amount of power
from an array. |
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Developments in modules and engineering
practices that allow PV to form an integral part of a buildings structure. |
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Convert DC (Direct Current) electricity to AC (Alternating
Current) electricity |
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Power |
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How much power do you need? |
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Battery charger |
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How flexible is the battery charging? |
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Generator control |
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Will the Inverter control a generator ? |
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Add ons needed / supplied |
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What other equipment is needed? |
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Trace SW Series |
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Prosine |
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ExelTech |
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Modified Square Wave inverters |
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Xantrex /Trace SW Inverter / Battery Charger.
Can be used stand-alone or Grid-Tied (with interface) |
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This is the workhorse inverter for many
standalone systems. |
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Available in 4kW and 5.5kW |
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Inverters can be combined to provide 240VAC, or
stacked in parallel to increase power. |
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Small, light inverters, often used in the RVs
and boats. |
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Innovative design that provides redundancy and
upgrade capabilities by adding modules. |
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No Battery charging capability. |
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Very high quality sine wave. |
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Non sine-wave are cheaper than sine-wave
inverters, but the electrical signal is much noisier. |
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Non sine-wave inverters can be used for
non-critical power requirements such as power-tools, heaters etc. |
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Non sine-wave inverters can ONLY be used in
standalone systems, they can NEVER be connected to feed power back to the
utility. |
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Store DC electricity for later use |
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Use ONLY deep-cycle batteries! |
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Wet batteries need to be checked at least every
6 months. |
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Check water and tightness of connectors. |
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Sealed Batteries (VRLA) do not need watering,
but may not last as long as wet batteries. |
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Battery capacity is measured in Ah (Amp Hours –
how many amps can the battery provide for an hour). The larger the capacity
the more energy can be stored, and normally the more expensive the battery. |
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To calculate the amount of power you can use
from a battery you need both the Voltage of the battery and its capacity. |
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Wh (Watt Hours) = Voltage ´ Ah |
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and is the amount of Power (W) that the
battery can provide for one hour. |
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The Voltage of the battery bank must ALWAYS be
matched to the Inverter, so if you have a 24V input inverter you would need
to add batteries in groups of 4 (4 ´ 6V = 24V). |
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You should never have more than 4 Parallel
strings of batteries. The batteries
will not share the load equally, and the life of the entire battery bank
will suffer. |
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The batteries must ALWAYS be kept in a well
ventilated area. They produce Hydrogen gas, that can explode if allowed to
build up. |
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Batteries contain Sulphuric acid that BURNS SKIN
on contact. |
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ALWAYS use insulated tools or wrap electrical
tape round the handles. If you touch both + and - terminals of a battery
with a metal you will start welding, at a minimum destroying the tool and
possibly starting a fire. |
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Charge Controllers (Solar Battery Chargers). |
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Disconnects and Switches. |
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Wind Generators. |
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Remote controls. |
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Meters. |
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Condition the power from the solar module to
charge a battery. |
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Modern units may be “Maximum Power Point
Tracking (MPPT)” may provide up to 30% more power to the battery. |
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Can be used in parallel to add more modules to a
battery bank. |
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National Electrical Code and Utilities require
disconnects for safety of the owner and utility workers. |
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Disconnect system components for installation
and maintenance. |
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Small wind generators can be excellent
compliment to a Solar system. |
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Can provide power at night. |
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Require a minimum of 5-7mph wind. |
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Moving parts require maintenance and
replacement. |
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Many systems offer remote control for
convenience, and some are now starting to offer performance monitoring by
computer or over the internet. |
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Collects data about system performance, and
sometimes local weather. |
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Can be very useful for isolating system
performance problems. |
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Often linked into remote control packages. |
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PV: Photo Voltaic |
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The physical principal behind the conversion of
light to electricity. |
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BIPV: Building Integrated PV: |
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The PV modules are integrated into the structure
of the building. |
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Net Metering: |
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The Utility company calculates the amount of
electricity they provided – the amount of electricity you put back to the
grid, and change only for the net electricity provided. Time scales for the
calculation change with utility company. |
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Grid -Tie / Line-Tie: |
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A system that can provide power back to the
utility company lines. |
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Modules, Panels, Arrays: |
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Assemblies of power producing photovoltaic. |
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STC: Standard Temperature Conditions: |
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A standard test temperature for PV systems to
quantify and compare components These conditions are rarely, if ever, seen
in service. |
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NOCT: Normally Operating Cell Temperature |
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A means to try and predict real-world system
performance. |
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Solar Electric vs. Solar Thermal: |
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Solar Electric (PV) systems convert light to
electricity. |
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Solar Thermal systems convert the heat from the
Sun into hot water, or heated air. |
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Time-of-day / Time-of-Use Rate: |
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The cost of utility power can vary depending on
when the power is used. Normally more expensive during the day (especially
afternoon) and cheaper at night. |
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UPS: Uninterruptible Power Supply |
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Provides
power when the utility grid fails. |
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VRLA Batteries: Valve Regulated Lead-Acid
Battery |
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Sealed battery requiring no maintenance other
than checking connections. |
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Gell Cell Batteries: |
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Sealed battery with the electrolyte in the form
of a gel. |
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AGM Battery: Advanced Glass Mat |
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Another form of spill-proof sealed battery. |
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Wet Batteries: |
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Lead-Acid batteries that have caps that allow
the water level to be checked and filled if needed. |
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L16, Group Number (e.g. Group 27), Golf Cart,
etc. Batteries: |
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These refer to the physical size of the battery,
which also has an effect on both the Voltage and storage capacity of the
battery. |
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AC (Alternating Current) |
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The current in the wire changes value 60 times a
second (60Hz). |
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AC is
easier to transmit over power lines without loss. |
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AC tends to be safer than DC as if you touch it
it will throw you away. |
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DC (Direct Current) |
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Voltage and current have steady (or very slowly
changing values) |
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Batteries, and Solar modules produce DC. |
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DC can be very dangerous, as it will cramp
muscles stopping you from moving away. |
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Inverter: |
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Converts DC to AC and often changes the voltage
too. |
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Sine Wave: |
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The shape of the electrical wave-form varies
smoothly, like the Utility power. |
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Square Wave: |
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The shape of the electrical wave-form changes
abruptly from one voltage to another. (only found in very old inverters) |
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Modified Sine / Square Wave: |
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A compromise wave-form found in cheap inverters.
Should only be used for powering simple loads (e.g. motors). Appliances
powered from a modified wave-form can buzz. |
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AZ Solar Center (www.AZSolarCenter.com) |
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Arizona Department of Commerce – |
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Energy Office (www.commerce.state.az.us/energy) |
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National Renewable Energy Lab (www.NREL.gov) |
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California Energy Commission (www.energy.ca.gov) |
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Florida Solar Energy Center (www.fsec.ucf.edu) |
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DOE (www.doe.gov) |
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Andrew Jones |
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Kyocera Solar Inc. |
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Kyocera Corp. |
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Wade Webb (Solar Webb) |
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Sundance Solar |
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Sandia National Lab and NREL |
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Exeltech |
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SMA America |
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Xantrex |
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Dan Aiello |
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SouthWest Wind power |
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Notes