With the increasing popularity of alternate power sources, such as solar and wind, the need for static inverters to convert dc energy stored in batteries to conventional ac form has increased ...

http://www.refurbups.com-- APC's Smart-UPS line is one of many that does do a pure sine wave output.

Purkeys’ Invert Pure Sine wave inverter uses the company’s DynaBalance monitoring technology that monitors the battery’s state of charge, even under load, rather than just its voltage. DynaBalance is ...