What are rectifiers and inverters

In order for the DC energy produced to feed into the grid network (to be distributed to homes and businesses alike), it needs to first be converted to AC. This is where inverters come in. An inverter is a device which converts direct current into alternating current at the required voltage. Fundamentally, an inverter accomplishes the DC-to-AC conversion by switching the direction of a DC input back and forth very rapidly. As a result, a DC input becomes an AC output. 

This is where the inverter sits in the solar farm system.

Yet it's also sometimes necessary to do the reverse and switch AC to DC. Renewable energy installations such as wind turbines and hydropower plants produce AC electricity. In renewables, the rule of thumb is that anything rotating is AC, whilst static equipment is DC.

Where, for instance, a wind farm is connected to battery storage, it requires the AC to be converted to DC in order to reverse the chemical reaction inside the battery and create chemical potential energy. To do this, you use a rectifier. It's the same process and equipment that is used for EV battery chargers which contain a rectifier in order to change mains AC to DC.

Across the transmission and distribution landscape you'll often find both inverters and rectifiers in action in the same transmission line; for instance where solar panels create DC energy - inverted to AC to be transmitted through the grid - only to be rectified back to DC to charge UPS in a datacentre.