The batteries in your PV systems store direct current (DC) power which can be used for certain applications but most of the conventional household appliances use alternative current (AC) power. The Inverter converts low voltage DC into higher voltage AC.
Electricity transmits more efficiently at higher voltages and it's the standard used worldwide. 120 or 240 volt in the USA at 60 cycles per second. Inverters are available in a wide range of wattage capabilities.
Brand-name inverters are highly reliable. Efficiency averages about 90% for most models, check the CEC certification before you purchase. Poor performance and high failure rates are common with cheap imported inverters without CEC certification.
Early inverters produced a square wave alternating current which at times resulted in problems while operating with solid-state equipment.
Now, modern inverters produce a modified sine wave which takes care of most of the problems that square-wave inverters had. Modified sine wave is not quite the same as power company electricity. They are lower cost, very efficient and most appliances will accept it although there are some notable exceptions. Check the additional information link on the right for inverter problems and troubleshooting. Modified sine wave inverters are a good choice for smaller sized PV systems.
True sine-wave inverters deliver top quality AC power (better quality than the power company). Because they work well with any appliance, they are becoming the standard for larger household power systems.
Inverter Output Ratings
Inverters are sized according to the watts they can deliver. All inverters are capable of briefly sustaining much higher loads than they can run continuously. For maximum performance, check the inverter's specifications for accurate continuous power rating.