Off-grid, or standalone, 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.
If the inverter is expected to run induction motors, like the ones found in top loading washers, dryers, dishwashers and large power tools, it must be designed to surge, or deliver power many times its rating fro short periods of time while these motors start.
Standalone (Off-Grid) inverters are available with two basic power output waveforms: sine wave, and modified sine wave. Exeltech, Xantrex XW, SMA Sunny Island, Magnum MS and OutBack FX inverters are sine wave off-grid inverters. Sine wave inverters have a higher cost, but they can operate almost anything that can be operated on utility power. The OutBack and Xantrex XW series inverters can be ganged together for up to 36 KW of output and can operate off-grid or grid-tie.

Xantrex TR series, Magnum, and Samplex PSE inverters have modified sine 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 efficiency makes them economical with power when running small loads like a stereo or a small light. Unfortunately, this type of inverter may destroy some rechargeable tools and flashlights, and laser printers and copiers. Equipment with silicon controlled rectifiers (SCRs) will not operate. Some audio equipment will have a background buzz that may be annoying to music connoisseurs.