What diesel generator should I use for my off-grid solar system

What AC back up generator should I use for an off grid system?

We have added a list with the minimum electrical requirements . Before you start the installation it is imperative to make sure that the generator is at least 1.5 time the power rating of the inverter. For example a Conversol 5kW inverter that powers an off-grid photovoltaic system, it works reliably with a 7.5kW back up generator or higher.

The off-grid hybrid inverters are equipped with a single phase ac-input terminal. While the AC input voltage may be vary in amplitude from 100-270AC there are some parameter that will affect the connection to the inverter.

If your generator (diesel, gas or petrol) has a low quality, unstable output voltage with wide fluctuation is frequency, the inverter will reject the power from the generator. We put in a simple table below the basic requirement for external AC source.

In UPS mode, the AC input waveforms should meet the following standards:
– Generator waveform THD: < 10%.
– Generator Vrms range: 180 ~ 270Vac
– Generator voltage crest factor(Vpeak/Vrms): < 1.6
– Generator peak voltage: <380V
– Frequency range: 45Hz ~ 63Hz
– Frequency slew rate:<0.3Hz/sec

In Appliance mode:
– Generator waveform THD: < 30%.
– If square wave output generator, output duty should greater than 60%
– Generator Vrms range: 100 ~ 270Vac
– Generator voltage crest factor(Vpeak/Vrms): < 1.6
– Generator peak voltage: < 0.3Hz/sec
– Generator peak voltage: <380V
– Generator frequency range: 45Hz ~ 63Hz

NOTE: Inverter-generators are recommended due to their cleaner output than conventional generators. If the waveforms of the generator such as voltage and frequency are distorted the inverter will reject the generator.