For Inverter connected generators above 72A/phase (17kVA 1ph / 50kVA 3ph) a separate assessment of harmonics must be carried out. This involves taking the individual harmonics of the generator and assessing their individual and cumulative impact at the connection point. 

The harmonic values given in Amps (only format acceptable) up to a minimum of the 40th Harmonic will be available from the manufacturer or possibly from a Type Test Certificate provided by the manufacturer. 

For Synchronous Generators it is not expected at present that harmonics will be an issue so details are not currently being requested.