The no-roads option is disabled although my site is smaller than 5ha, why?

Apart from the area restriction of the site (5ha), pvDesign also requires all inverters to be connected to one power station to enable the “no roads” option. To achieve that, the user needs to define the size of the power station (Equipment > Power Station) to allow all inverters to fit. The size can be estimated by the total power output of the PV plant and the power output of one inverter.