The inverter is that device of tranforming the current from DC current comming from the Photovotaic panels to AC current going to the consumer or to the net.
Inverters have several capacities and specification depending on the usage. In order to choose the correct inverter the user has to defined first the capacity in KW which he need. Should capacity be more or less equal to his consumtion and to his PV purchasing.
The user has also to fix his requirment of the outlet voltage from the inverter. it can be mono phase 220V , or three phase of 380 V. beside that the frequency of the inveter has to be equal to the frequncy in the country where the inveter will be installed.