Simple Backup System

A simple backup system consists of only an inverter/charger and a battery bank as depicted below. The inverter incorporates an automatic transfer switch (ATS). When utility power is available it is passed directly to the load, but in the event of a power cut the ATS, in a split second, connects the load to the output of the inverter, which draws DC power from the batteries and inverts it to AC power. These types of inverters usually incorporate a battery charger which charges the battery when utility power is available.

Simple Solar System
With Battery Backup

By adding solar panels with a charge controller to a backup system as shown below, it can be upgraded to a full solar system.

Grid-Tie System

By adding solar panels with a charge controller to a backup system as shown below, it can be upgraded to a full solar system.

Grid-tie System
With Battery Storage

The advantage of this type of system is improved efficiency since power from the grid-tie inverter is fed straight into the high voltage AC supply line without the need to step the power up from the low battery voltage (12-48V DC) to the AC supply voltage (240V AC), which is not very efficient.

The type of inverter used in this configuration is called a bi-directional inverter since solar power from the grid-tie inverters can be fed back into the grid. It can also be used to charge the batteries.

A well-known example of bi-directional inverters is Victron inverters.

Smart Integrated Solar Systems

Advanced smart systems usually integrate the grid-tie inverter, battery inverter and charge controller into a single unit. The system manages four sources of power (utility, generator, solar & batteries) and three types of loads: essential, non-essential and smart loads. Essential loads are those that will always be powered, even if the grid is off and the generator fails. Smart loads are non-essential loads (e.g. hot water tank) that will be powered from the grid or from redundant solar power if the grid is off. The smart inverter controls the flow of energy to ensure optimum efficiency and availability of power.

Good examples of this type of inverters are Synsynk and Deye inverters. These inverters can also be classified as on-grid hybrid inverters.