High-voltage inverters generally offer better efficiency because higher voltage means less current, which leads to reduced heat and less energy lost in the wires.
Inverters are not 100% efficient. Most have 85%–95% efficiency, meaning some power is lost during conversion. Also, power factor (how efficiently a device uses the electricity) affects perceived output.
An old or damaged battery may not be able to provide sufficient power, leading to low voltage from the inverter. Faulty wiring can also result in voltage fluctuations.
String inverters are designed to connect to individual strings of PV modules, while centralized inverters aggregate the power output from a large number of PV modules.