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Solar systems are defined by the type of inverters they use to produce electricity. There are a number of types and brands available. Which type of inverter is the best for your requirements?

We will try to simplify the system design by discussing the different inverters available to you.

  • Grid-Tied
  • Off-Grid
  • Hybrid
  • Bi-Directional

Grid-Tied Inverters

Grid Tied systems is very simple in design and consists of 2 components:

  1. Solar modules that collect sunlight and convert it into DC electricity
  2. Inverter which receives the DC current and converts it into AC grid power

This is how it works

The Inverter is connected to the building through the distribution board.

The inverter prioritize the Solar Power supply so that the solar power is always used first.

When the electricity consumption is less than Solar Power supply, no electricity will be drawn from the Grid, but the excess electricity may be feed back into the grid for credit.

When the electricity consumption is more than what the solar power system can supply, Eskom power is used to supplement the demand.

There is no switching between Solar Power & Grid Power, but rather a continuous supply of both Solar Power & Grid Power with Solar Power supply being the first priority.

There is no limit to the power supply of Grid Tied systems.

Grid Tied systems are ideal for reducing electricity costs, and offers the best Return on Investment of 2 to 4 years.

Off-Grid Inverters

Off Grid systems are not connected to the Eskom grid, but use solar power as the primary electricity source. Off Grid systems consists of the following components:

  1. Solar modules that collect sunlight and convert it into DC power
  2. Batteries
  3. Charge controller that charge the batteries
  4. Inverter that converts the battery DC power into AC power

(The charge controller and inverter may be combines in one unit)

This is how it works

The charge controller charges the batteries from the solar modules.

The inverter convert the DC battery power to AC power on demand.

If the batteries charge is low, it will not generate any electricity.

If the batteries charge is low, it might start a generator to supply power to the house, and charge the batteries.

Off-Grid systems are ideal for the following scenarios:

  • New building where the cost of connecting to power Eskom is too high
  • You wish to be completely independent of Eskom
  • The monthly fixed connection cost is exuberant relative to the consumption cost

Off Grid systems can use a generator as backup.

Hybrid Inverters

Hybrid solar systems use Solar power to charge Batteries and supply power to the building. Eskom power is used as backup power. Hybrid systems consists of the following components:

  1. Solar modules that collect sunlight and convert it into DC power
  2. Batteries
  3. Charge controller that charge the batteries
  4. Inverter that converts the battery DC power into AC power

(The charge controller and inverter may be combined in one unit)

This is how it works

The charge controller charges the batteries from the solar modules.

The inverter convert the battery power to AC power for the building on demand.

If the batteries charge is low, it will switch to use Eskom power.

If the batteries charge is low, it might use Eskom power to charge the batteries.

Hybrid Systems are ideal for the following scenarios:

  • Ensure a steady power supply, even during power outage
  • Extra solar power generated during the day is stored in batteries for consumption at night

The Hybrid system needs to be sized correctly to handle the maximum load. Multiple Hybrid Inverters can be interconnected to increase the load capacity of the system.

Bi-Directional Inverters

Bi-Directional Systems combines the best of two systems: Hybrid and Grid Tied.  Bi-Directional systems consists of the following components:

  1. Solar modules that collect sunlight and convert it into DC power
  2. Batteries
  3. Charge controller that charge the batteries
  4. Inverter that converts the battery DC power into AC power

(The charge controller and inverter may be combined in one unit)

This is how it works

The charge controller charges the batteries from the solar modules.

The inverter convert the battery power to AC power for the backup circuits on demand.

The inverter generate Electricity from the extra power from the sun and send it to your building to use.

If the batteries charge is low, it will switch over to Eskom power.

If the batteries charge is low, it might use Eskom power to charge the batteries.

This is a dual Solar system where one channel uses Solar power to charge batteries and supply power to the building. A second channel supplies Solar power directly to all other circuits in the building when the sun shines.

This solution is ideal for the following scenarios:

  • Ensure a steady power supply to dedicated circuits, even during power outage
  • Solar power keeps the batteries fully loaded for backup at night
  • Extra solar power reduce the electricity usage of the whole building