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.
A String inverter is connected to a series of solar panels rather than to just a single panel as in the case of micro inverters. AC current from a string inverter can then be combined with output from other String inverters. A “string” here means series of solar panels. The rated Maximum DC input power (Pdcmax) for these inverters will be in the range of 2 – 30kWp.Here is the short video on their string inverters from ABB.
A Central inverter is connected to a series of strings of solar panels rather to just a single string as in the String inverter. In this architecture, the generated DC power from a series of solar panels is connected in parallel with the output from other series of solar solar panels at a combiner box. The DC output from a combiner box is then connected to a single central inverters. The rated Maximum DC input power (Pdcmax) for these inverters will be in the range of 50 – 1MWp. Here is the short video on their Central inverters from ABB.
There are practical advantages and disadvantages to each type of solar architecture. We will discuss merits and demerits of each in a different blog post.