Net-Metering means that the extra electricity your system produces on the day you are not using it is returned to the grid. The EAC will give this electricity back to you at night or whatever you need. The maximum power is 10,4kW.
Net-Billing means that the extra electricity your system produces on the day you do not use it is bought by EAC at the proven tariff. You can use the accumulated credit for energy company settlements. Systems up to 8MW.
Virtual net-metering/billing works in the same way as net-metering, except that the photovoltaic system is installed at a different location from the property.