Its of great importance for any solar investor to understand the different solution designs and what each design allows. South Africa ‘s load shedding problem is rather unique and most global markets do not face this challenge. Therefore a lot of products on the market do not cater for this as a regular phenomenon. Inverter features are often limited with particular goals in mind. In making a choice these must be understood before finalising a decision. Single- or three phase inverters are available for all types described below.

Back-up

Essentially a UPS function. I.e. a battery is kept charged from grid power while the grid power is on. As soon as it goes down, the inverter makes use of the DC power stored in the battery to supply AC power to the load. Solar power may be used to charge the battery but is typically not used in pure backup solutions. Application: Purely to have power during load shedding or power failures.

Off-grid, also referred to as island or Isolated

As the name suggests this type of inverter operates isolated from the grid. It makes use of DC power stored in a battery to supply an isolated load with AC power. Application: Complete off-grid scenario’s like deep rural villages or angry Eskom clients.

Grid tie

This type of inverter is always connected to the grid. It purely combines 2 sources of AC power, i.e. Eskom and the local solar plant. The direction of current flow through the site meter is determined by the net power flow to the site: If load is more that the solar capacity it pulls the difference from the grid. If the load is less, the surplus solar power feeds back into the grid. Grid tie inverters require the grid to be on – it locks its AC phase onto that of the grid. If the grid goes down, so does the inverter. Grid tie inverters are therefore not an answer to load shedding. . Application: To decrease grid-supplied power and associated bills. Not a solution to load shedding.

Grid interactive, also referred to as hybrid

This is the most advanced type of inverter combining all the features of other types. It functions as the grid tie inverter, but also has a DC bus where a back-up battery is kept charged similar to the off-grid type. In case of a power failure the inverter seamlessly switches over to support its AC load from the battery. During day time when surplus solar power is available, it is fed back into the grid. A distinguishing factor of advanced hybrid inverters is the ability to blend various power sources simultaneously e.g. solar + grid or battery + grid or solar + battery + grid. This is very beneficial when designing an intelligent system removing the requirement for excessive battery banks as in off-grid solutions. Application: To decrease grid-supplied power consumption and a solution to load shedding. Grid feed must be allowed and supported by the site electricity meter.
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Backup Off-Grid Grid-Tie Grid Interactive Grid Support Capacity
Conext SW 2.5-4kW
Conext XW/XW+ 7-8.5kW
Conext RL 3-5kW
Conext CL 20-25kW

Lumax also distributes inverters of the following brands:

  • ABB
  • Solar Edge
  • SMA
  • Chint
  • Axpert & Infini Solar

Inverters

Schneider Electric Connext SW

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Schneider Electric Connext XW / XW+

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Connext RL

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Connext CL

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Other Components

Schneider Electric Connext MPPT 60 150

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Schneider Electric Connext MPPT 80 600

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Schneider Electric Connext Combox

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Connext Battery Monitor

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Connext Auto Generator Start

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Lumax will ensure to implement the appropriate inverter

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