A modular adjustable power factor renewable energy inverter system, the system comprising: a plurality of inverter modules each having a dc power input and an ac power output; a common grid power feed coupled to each said inverter module ac power output; and a system controller having a communications link to each said inverter module to receive power data from the inverter module and to send control data to the inverter; wherein each said inverter module further comprises: a series combination of a capacitor and a controllable switching device connected in parallel across said ac power output; a communication interface for communicating with said system controller; a power measurement system coupled to said communication interface to measure one or more parameters relating to a net level of ac power provided by said inverter module to said common grid power feed, and to provide power data, defining said net level of ac power provided, to said communications interface for transmission to said system controller; and a power factor controller, coupled to said communications interface to receive control data from said system controller, and coupled to said controllable switching device to control said switching device in response to said control data to switch said capacitor into/out of parallel connection across said ac power output of said inverter module; and wherein said system controller is configured to: receive said power data from each said inverter module; sum the net level of ac power from each said inverter module to determine a total net level of ac power provided by said plurality of inverter modules to said common grid power feed; determine a number of said capacitors to switch into/out of parallel connection across their respective said ac power outputs responsive to said total net level of ac power; and send control data to said inverter modules to switch said determined number of capacitors into/out of said parallel connections. a plurality of inverter modules each having a dc power input and an ac power output; a common grid power feed coupled to each said inverter module ac power output; and a system controller having a communications link to each said inverter module to receive power data from the inverter module and to send control data to the inverter; wherein each said inverter module further comprises: a series combination of a capacitor and a controllable switching device connected in parallel across said ac power output; a communication interface for communicating with said system controller; a power measurement system coupled to said communication interface to measure one or more parameters relating to a net level of ac power provided by said inverter module to said common grid power feed, and to provide power data, defining said net level of ac power provided, to said communications interface for transmission to said system controller; and a power factor controller, coupled to said communications interface to receive control data from said system controller, and coupled to said controllable switching device to control said switching device in response to said control data to switch said capacitor into/out of parallel connection across said ac power output of said inverter module; and a series combination of a capacitor and a controllable switching device connected in parallel across said ac power output; a communication interface for communicating with said system controller; a power measurement system coupled to said communication interface to measure one or more parameters relating to a net level of ac power provided by said inverter module to said common grid power feed, and to provide power data, defining said net level of ac power provided, to said communications interface for transmission to said system controller; and a power factor controller, coupled to said communications interface to receive control data from said system controller, and coupled to said controllable switching device to control said switching device in response to said control data to switch said capacitor into/out of parallel connection across said ac power output of said inverter module; and wherein said system controller is configured to: receive said power data from each said inverter module; sum the net level of ac power from each said inverter module to determine a total net level of ac power provided by said plurality of inverter modules to said common grid power feed; determine a number of said capacitors to switch into/out of parallel connection across their respective said ac power outputs responsive to said total net level of ac power; and send control data to said inverter modules to switch said determined number of capacitors into/out of said parallel connections. receive said power data from each said inverter module; sum the net level of ac power from each said inverter module to determine a total net level of ac power provided by said plurality of inverter modules to said common grid power feed; determine a number of said capacitors to switch into/out of parallel connection across their respective said ac power outputs responsive to said total net level of ac power; and send control data to said inverter modules to switch said determined number of capacitors into/out of said parallel connections.