Solar Grid Connect Inverters
These convert the DC power from photovoltaic (PV) modules directly into AC power to be fed into the grid. Storage batteries are not needed, as any power produced that is not consumed by the owner’s electrical loads is fed into the grid to be used elsewhere.
String Inverters
Solar grid connect inverters are also called “string” inverters 
because the PV modules must be wired together in a series string to obtain the required DC input voltage, typically up to 600 VDC in residential systems and up to 1,000 VDC for commercial and industrial systems. String wiring is quick and easy to install, and the higher voltage helps to minimise cable losses and allow smaller wire size. However, in string wiring, maximum power point tracking (MPPT), along with any monitoring output, is performed at the string or array level.
Module Optimisers
Module Optimisers can be used, connected to each module to 
provide individual module-level MPPT tracking and monitoring, optimising the DC output that is connected to a string inverter for very high efficiency. Systems that combine optimisers with low-cost high-efficiency string inverters can simplify system design and maximize safety.
For products see:
SMA Inverters
and
SolarEdge Inverter & Optimisers
Due to the high voltages involved, these inverters should only be installed and serviced by qualified personnel.
