Solar Central Inverter
It used in photovoltaic solar system in which a number of solar panels are connected in series with each other providing a string, then one string or more will be connected to a single solar inverter called central inverter. The inverter will convert strings DC voltage to AC voltage which can be usable in our house to run our appliances/equipment or to be connected to the electricity grid forming grid tie solar system. Usually the number of solar panels in one string are between five and thirteen panels, it differs based on what will be required string overall power capacity and DC voltage. The central inverter may have one MPPT input of more, if it has one MPPT input, this means that it accepts one or more strings which are the same, we mean they must be equal in number of panels and output power capacity.
Solar Micro Inverter
This solar inverter DC input will be connected to one solar panel and may be two solar panels. The AC output from several micro inverters will be combined together and feed an electrical grid switchboard, so each one or two solar panel existing in the solar system array may have a different orientation to gather the maximum amount of solar radiation.
Which one is better?
There are many advantages of micro inverter over central inverter, the first advantage is that micro inverter is performing much better in case of shading, as if there will be a partial shading on a part of our solar system due to chimneys or trees, the overall output power of the string will not be affected, but only the shaded solar panel output power will be affected, while in central inverter the overall output power of the string will be affected, and there will be much power loss. The second advantage is the capability of micro inverter to track maximum power point for each connected solar panel, resulting in high efficiency and output power from the solar system.
The main disadvantage of micro inverter is its high initial costs over the central inverter, as we use many micro inverters to be equivalent to one central solar inverter, also the several micro inverters existing on the site will increase the system complexity, then the probability of fault happening and this will lead to more expensive site services.