What is an Inverter?
An inverter or PCE ) power conversion equipment) simply converts dc current fro the solar array, batteries or other dc source into ac current which is suitable to export into the grid or run appliances. Its output must be pure sine wave. All inverters must comply with AS/ANZ4777.2:2015 and be listed on the CEWC approved inverter list (http://www.solaraccreditation.com.au/products/inverters.html) if you want to create STCs (small technology certificates). If it isn't on the list then its simple - don't install it.
All inverters must be installed in accordance with Australian Standards and under the Clean Energy Council guidelines.
INVERTER CATEGORIES AND SUB CATEGORIES...
Grid Connected inverters
Back up mode
What is a grid connected inverter?
A grid connected inverter is an inverter which is connected to the grid with the capability to export power into the grid or supply loads in parallel to the grid. A GC inverter must synchronise to the grid ( or other AC source) to operate and when the grid is interrupted, or goes outside the pre-set frequency or voltage limits then the GC inverter must shutdown (anti-islanding function).
The most popular type of inverter used in small scale solar systems. PV modules connected in series are connected to a string-inverter with a dc cable. In residential, there is typically only one required, usually mounted close t the electrical switchboard.
The number of configuration of the solar modules connected to a string-inverter must not exceed the input voltage and current specification on the inverter.
String-inverters may have one or more MPPT (multiple power point trackers) connection.
A central inverter is usually only used on solar installations over 1MW. All the solar strings are wired back to a central point, which may make monitoring and maintenance easier however it presents a single point of failure.
A microinverter is simply a very small inverter sized for each individual PV module. Micros are mounted under the panel and converts the dc current from the PV module into ac current and is connected fro the PV module to the switchboard with an ac cable. Each mircoinverter acts as an individual MPPT for the connected PV module.
Technically not an inverter as dc optimisers needs to be connected to a special string inverter near the switchboard. DC optimiser act the same as, but different to, microinverters. The main difference is the dc from the PV module is connected to the inverter with dc cable.
The PV array is directly connected to the hybrid inverter as well as the grid. The hybrid inverter will charge the battery storage and converts the dc current from the battery storage into ac current for the attached loads . Hybrid inverters do not supply ac current when the grid is disconnected.
What is a Multi-Mode Inverter?
A multi-mode inverter is an inverter which operates in more than one mode, that is it operates from the grid when available and off-grid mode when the grid is disconnected. A multimode inverter requires battery storage to be connected to operate in the off-grid mode.
Back Up Mode
Multimode inverters with backup or off-grid functionality operates from the grid when available. When the grid is interrupted, the mutlimode inverter will shut down, then restart in the backup or off-grid mode. There is a time lapse of about five seconds between the grid and off-grid mode which will shout down al the appliances connected.
A multimode inverter with UPS functionality operates from the grid when available however when the grid is interrupted, the changeover from grid to off-grid is instantaneous (less than 30ms) and will not shut down the connected appliances.
What is a Stand-Alone Inverter?
A stand-alone inverter does not need the grid to be connected to supply AC Power to the loads. A stand-alone inverter is connected to battery storage that is recharged by PV or other renewable source. A genset may also be connected .
The stand-alone inverter can be the same as a multimode inverter but cannot have a connection to the grid.