There are three type of On grid or grid-tie inverters (for details on what is a grid-tie inverter, you can refer to an earlier post http://goo.gl/0jtWMl). They are 1. Micro inverter 2. String inverter 3. Central inverter. A Micro inverter is connected a single solar panel to convert its generated DC current to AC current. This AC current from each micro inverter is then combined together with the output from other Micro inverters to send it to the grid. Typical ratings for Maximum DC input power (Pdcmax) Micro inverter are typically around 250Wp to 300Wp. That’s the Maximum size of the panel that can be connected to each Micro inverter. Here is the short video on their micro inverter from ABB.