Because there is a difference between DC and AC electricity, inverters and inverter/chargers exist. An inverter converts DC electricity (battery power) to AC electricity and a charger does the reverse. This technology allows us to store energy which is produced from a solar system, electricity grid or generator in batteries and then convert it later into AC electricity (household power).
Inverters have become very common, although there is a wide disparity between prices and quality levels. The cheapest inverters are known as “high frequency” types, meaning that the transformation to alternating current occurs near the output voltage, making them lighter and less expensive, but also less durable. Most high frequency inverter/chargers have small chargers. “Transformer type” inverters convert the power at a low voltage and then step it up to the output voltage through a large transformer. This makes them heavier and more expensive, but also more reliable and resistant to surges. Because they have large transformers, it also makes them ideally suited to be inverter/chargers. In Africa we always recommend transformer type inverters.
Early inverters were crude devices that would switch polarity abruptly, creating a square wave signal. Later, companies like Trace Engineering improved the square wave to pause for a few milliseconds at zero, making a modified square wave which the marketers called a “modified sine wave”. Eventually manufacturers developed true sine wave units and the sine wave inverters we carry now are comparable with utility power. Modified sine wave inverters have also improved and now all feature power factor correction, making them more efficient. Modified sines are popular because they are much cheaper than sine waves, although they will transmit static into sensitive electronic devices such as phone systems or stereos, and they will cause motors to run hotter and noisier, shortening motor life in some cases. They also are not recommended with flat screen TVs.