The risk of fire caused by solar systems is very low and in the vast majority of cases caused by low quality products or installer errors that lead to an electrical arc and then fire. The chance of a fire being caused by an arc in your solar system is comparable to the same risk carried by most electrical appliances such as a TV.

Despite this low risk, at Autarco we have taken all possible steps to reduce risk. As a total solutions brand, we are in position to control these risks far better than a brand that only produces one product like a solar panel manufacturer or solar inverter manufacturer.

Read on to find out more.

What is an Arc Fault?


An arc is formed by separating two parts of a circuit where a current is running. A plasma is formed between the 2 parts emitting light and heat. The plasma is a good conductor, so in other words the current will keep flowing and the arc will continue until one of below;

  • The voltage in the circuit is reduced to less than 12V
  • The distance between the 2 parts is closed
  • The distance between the 2 parts is increased far enough to break the arc

In a solar system, the rooftop current is a direct current which makes arcs more troublesome than in an AC circuit where the voltage goes to zero (50-60 times in one second, according to the grid frequency).

The large energy produced by arcs can be controlled in certain industrial applications such as welding and plasma cutting and they are also commonly used in lighting applications. If uncontrolled, the hot plasma may cause damage and will cause plastic parts to melt and potentially cause fire.

Possible causes of an arc in a solar system


There are numerous connection points in a solar system that are potential flash points for electrical arcs to occur. You can think of these points simply as switches and plugs.

Plugs
Individual solar panels have connectors (plugs) on the end that are joined together. The ones that come on the solar panels are installed in highly automated production lines with stringent quality control. The installer just needs to make sure they hear a “click” when they connect the plugs and then the risk is incredibly low.

The connectors on the cable that connects the panels on the roof to the inverter on the ground are added by the installer and this introduces two risks;

  1. They use a different brand of connectors to those on the solar panels
  2.  They do not install the connectors properly.

As a total solution brand, Autarco uses approved dealers and provides all connectors of the same brand to our professional install partners.

Switches
Some form of DC switch is mandatory at the solar inverter, so the inverter can be safely disconnected from the solar panels for maintenance etc. Often referred to as a DC Switch or DC Isolator.

  • When an installer is not suitably trained or is trying to save costs they may install an external switch that is not suitable for the solar system which can result in arcs.
  • Beyond incorrect product choice, the connections in the external switch may also be poorly done. Autarco dealers and installers receive instructions how to install these switches properly.

Autarco inverters have an integrated DC switch, so they are always properly matched and installed under strict quality control.

External Causes
Animals chewing through wires can also lead to arcing. By proper separation of the DC-cables, propagation of the arc is prevented.

Prevention


Prevention beats detection every time. That’s why we have deployed innovative technologies and processes in our total solutions to mitigate the three main causes of unsafe situations.

  • Product Quality
  • Design Safety
  • Install Quality

You can read more about this on our safety page.

Detection


In addition to our prevention measures, new Autarco inverters are now available with inbuilt Arc Fault Detection. This means that the inverter can detect an arc in line and will then shut down and send an alarm.

The detection in Autarco inverters conforms with UL1699B-2018, which is an American standard, but is currently the only available standard for arc fault detection in the world. As new standards (the European organisations are working on one now) become available, our inverters can be upgraded to comply with them.

There is still an additional risk: if the sun is shining there is always a voltage between the panels even if the inverter shuts down, so the arc may not be extinguished by inverter shutdown. By adding optimizers to each solar panel it is possible to reduce voltages of all panels on the roof to a safe value.

Read more about Autarco and safety

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