Autostart generators are capable of remote start, meaning that these units can be started by an external signal, such as one that might come from an inverter when it detects a set battery voltage level. The control over the generator’s operation—that is, when to run and when to stop—is external to the generator, while the generator provides its own safety protection, such as shutoff for low oil level, overheating, and other factors.
Among remote-start generators, the simplest is the “two-wire start,” in which a closed contact tells the generator to start and run. When the contacts open, the generator stops. All inverters with generator-start capability can control the generator in this method, as can other system components such as a manual switch, a voltage-controlled relay, a threshold signal in some system monitors, and even a signal triggered by a big load.
Automatic generator operation is at best a mixed blessing. In theory, the inverter calls for the generator to provide backup charging power whenever the RE source proves insufficient. However, numerous real-world bugs can interfere with such seamless operation. Automatic operation can lead to a system owner failing to perform regular maintenance, and neglecting something as simple as checking oil levels can cause unintended problems that aren’t noticed until the entire system shuts down. Poor programming can lead to excessive runtime and fuel consumption, yet not guarantee that batteries are adequately charged.
The most likely path to eventual failure is total dependence on a generator in an unattended system. “Auto-generator start systems built into all of the inverter systems should be viewed as a convenience device,” cautions Christopher Freitas of OutBack Power Systems, “not as a comprehensive, ‘bullet-proof system’ which will operate 100% of the time.”
Longtime installer Todd Cory is more blunt: “I never configure autostart generators. Having a machine automatically start/stop while unattended is at best a recipe for damage to gear and, at worst, a fire that could destroy the entire homestead.”