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Inverters
Most North American electrical devices require 120 volts of alternating current (AC) power. Solar arrays, wind turbines
and micro-hydro generators supply voltage that is direct current (DC). In order to use common electrical appliances powered from an alternative energy source a DC to AC inverter must
be used. Inverters convert the incoming power from DC voltage and to 120 volts AC.
With any conversion there is a loss of efficiency. Today’s
inverters have reduced the efficiency losses and boast an efficiency rating as high as 96%. Power coming from utility providers such as Hydro Ottawa, alternate their current in the form of a sine wave. Inverters try to duplicate this sine wave using a variety of techniques. The best techniques will be the closest approximation to the utility providers sine wave. There are three types of inverters available on the market and the cost difference between each type can be dramatic: square wave inverters, modified square wave inverters, and sine wave inverters.
Square wave inverters are the most primitive form of inverter. They alternate power in one step. This is unacceptable for many forms of electrical devices and is not recommended.
Modified square wave inverters are the most common form of inverter that is available. They alternate power in two steps. This is acceptable for 98% of typical electrical loads such as fluorescent lights, TVs, stereos, vacuums, power tools et cetera. However, certain devices like TVs and stereos will experience a hum. Sensitive devices like laser printers, dimmer switches, and small rechargeable devices will experience difficulties and may not work.
Sine wave inverters try to mimic utility power by alternating the current in several steps. The more steps used the closer the approximation to utility power. This eliminates any hum or noise and is acceptable for all electrical devices.
Three brands offered by Quallium are: Outback, Xantrex, GoPower, and Magnum.
Outback
They produce sealed and vented inverters ranging from 2 kW up to 3.6 kW. All Outback inverters have the following
features:
- extremely rugged
- smooth true sinewave AC output using 330 steps (instead of 34-52 steps in other brands)
- additional inverters can be added in parallel, series or 3-phase configurations, up to 36 kW
- high surge power protection
- high efficiency >90%
- can be networked together for monitoring and control
- available in fully sealed or vented configurations
- grid tie compatible without additional accessories
Xantrex
There are two series of Xantrex inverters, DR and SW. The DR
inverters are modified square waves that come in three sizes 1500, 2400, and 3600 Watts. They feature:
- front panel LED indications and switch selector
- selectable settings for lead acid, gel or absorbed glass mat (AGM) batteries
- greater than or equal to 94% efficiency
- three stage battery charging
The SW series provides 34-step sine wave output that handles
most sensitive loads. They are available in three sizes: 2500, 4000, and 5500 Watts. In addition to the features available in the DR series they offer:
- digital display
- four stage battery charging
- ability to save customized settings
- a GTI option that allows grid tie hook-up
GoPower
GoPower offers both modified square wave and sine wave
inverters. They specialize in small-scale power outputs ranging from 150, 300, 600, 1000, 1500 to 2000 Watts. Their low cost and ease of installation make them ideal for first time users.
Magnum
Magnum products are ideal for RV and marine uses. The RD and ME series models are an inexpensive alternative to Outback and
Xantrex inverters.
The RD series is a modified square wave inverter that offers:
- 80-88% efficiency
- battery charger with temperature sensor
- RS 485 communications port
The ME series is a sine wave inverter that offers the same
features as the DR series with a higher efficiency rating (88-96% depending on conditions).
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