STAND-ALONE INVERTERS convert DC power stored in batteries to AC power that can be used as needed. Select an inverter for your power system based on the maximum load you will be powering, the maximum surge required, AC output voltage required, input battery voltage and optional features needed. High quality stand-alone inverters are available in sizes from 100 watts, for powering notebook computers and fax machines from your car, to 500,000 watts, for powering a commercial operation. The size of an inverter is measured by its maximum continuous output in watts. This rating must be larger than the total wattage of all of the AC loads you plan to run at one time. Wattage of most AC loads can be determined from a tag or label on the appliance, usually located near where the power cord enters, or from the owner's manual. If the inverter is expected to run induction motors, like the ones found in automatic washers, dryers, dish washers and large power tools, it must be designed to surge, or deliver power many times its rating for short periods of time while these motors start.
Stand-alone inverters are available with two basic power output waveforms: modified square wave (often called modified sine wave) and sine wave. Intertie, multifunction inverters and utility companies deliver a sine wave.
Trace UX series, DR series, and TS series inverters and Intertrix inverters have modified square wave output with harmonic distortion of around 40%. They are an economical choice in power systems where waveform is not critical. Their high surge capacity allows them to start large motors while their high efficiency makes them economical with power when running small loads like a stereo or a small light. They can power most lighting, televisions, appliances and computers very well. We do not recommend them for computer systems with laser printers. Unfortunately, this type of inverter may destroy some low cost rechargeable tools and flashlights, and laser printers and copiers. They may not allow many laser printers, copiers, light dimmers and some variable speed tools to operate. Equipment with silicon controlled rectifiers (or SCRs) will not operate. Some audio equipment will have a background buzz that may be annoying to music connoisseurs.
Exeltech, AEI MM Series, Trace SW Series, and Studer inverters are sine wave inverters. Sine wave inverters have a higher cost, but they can operate almost anything that can be operated on utility power. Exeltech sinewave inverters are an excellent choice for power systems running audio or telecommunications equipment and other electronics that are waveform-sensitive. The AEI MM and Trace SW series inverters can be ganged together for up to 15 kW of output and can operate off-grid or intertied. We now carry Studer inverters for a lower cost, small system sine wave alternative.
Sunny Boy, AEI CG, and Trace ST are intertie inverters. Intertie inverters change DC power into AC power to be fed into the utility grid. A power system with this type of inverter uses the utility company as a storage battery.
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When the sun is shining, your electricity comes from the PV array, via the inverter. If the PV array is making more power than you are using, the excess can be sold to the utility (power company) through an electric meter. If you use more power than the PV array can supply, the utility makes up the difference. This type of system makes the most sense if you have utility power, because there are no batteries to maintain or replace, but it can have a long payback period depending on your electric rates. Using a multi-function inverter allows you to sell excess power to the utility, and also maintain a battery bank for standby power in the event of a utility power failure.
The new AEI MM series and Trace SW series are multifunction inverters that can operate as a stand-alone inverter and as an intertie inverter at the same time. In a typical installation, the inverter is connected to a battery bank, the utility power lines, a standby generator and the house load center. If the utility is available, the inverter will supply the house loads from the utility. If the utility fails, the inverter will supply power to the loads from the battery. When the utility is available again, the inverter will switch the loads back to the utility, and recharge the batteries. If the batteries become fully charged by another power source, such as photovoltaic modules or a wind or hydroelectric generator, excess power may be sold back to the utility. If a standby generator is connected, it can also supply power to loads while charging batteries.
Interference
The electronic circuitry in inverters may cause problems with radio and television reception, noise on telephones and buzz in audio equipment. Sine wave inverters cause the least amount of interference. Interference can be minimized by locating the inverter very close to the batteries, twisting together the cables that connect the inverter to the battery, running AC lines separate from other wiring (such as telephone wires) and locating the inverter away from appliances that are susceptible to interference. All inverters cause interference on AM radio!
Output Voltage
We sell inverters that supply standard 120VAC 60 HZ (and stacked inverters for 240VAC), such as one gets from utility companies and fuel-powered generators. Most of them can be special ordered with other output voltages and frequencies for use anywhere in the world. See our export models and contact us with any special requirements that you have.
NOTE: Use caution when plugging a small inverter into a lighter outlet located far from a battery. Typical house wiring may have too much voltage drop to supply the current required by these inverters.
For sinewave inverter products click here.
For modified sinewave inverters click here.
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