FREQUENTLY ASKED QUESTIONS

To help you choose a safe solar solution for your home or business, we’ve compiled the answers to some of our frequently asked questions.

SAFE SOLAR AND YOUR HOME OR BUSINESS

AC solar systems (that incorporate microinverters) and some DC optimised systems eliminate or minimise the fire and safety risks associated with DC arcs.

Information about safer solar technologies can be found here.

Microinverter and some DC optimised solar systems are immune to DC arc faults and are just as safe as other electrical wiring running through your house or business.

If you have a conventional DC solar system installed, it will almost certainly have unprotected DC cabling running from the solar panels on the roof down to the inverter. The string inverter is typically mounted on the wall adjacent to the main switchboard. A fault of any sort on this DC circuit has the potential to result in a fire.

It is strongly recommended that conventional DC Solar systems are inspected by a CEC accredited solar installer every 12 months. However, even having the system regularly inspected will not eliminate the risk of DC arc faults, which can be caused by a wide variety of factors and can occur at any time. For example, a DC arc fault can occur simply by a rodent biting through the cable insulation, water entering any part of the circuitry, or corrosion at any of the various DC cable connections.

There are three types of solar systems commonly available in Australia:

  1. Conventional DC solar systems
  2. DC optimised systems
  3. Microinverter-based systems

The type of system is determined by the kind of inverters that have been installed.

Conventional DC solar systems generally have a large inverter and several electrical switches mounted on the wall adjacent to the main switchboard.

DC optimised systems are similar to conventional DC systems. However, a DC optimiser is also installed under each solar module.

Microinverter based systems do not have a large wall-mounted inverter as the inverters are located under each solar module.

The best way to establish the type of solar power system you have installed is to consult with the company that supplied the system or to seek advice from a CEC (Clean Energy Council) accredited solar installer.

Yes, safer solar technologies are readily available and can be retrofitted to existing DC solar systems to eliminate the risk of DC arc faults.

This involves replacing your existing string inverter with either microinverters or a DC optimised system. It is not usually necessary to replace the solar modules themselves – just the inverter.

Contact a CEC accredited solar installer or click here to lodge an enquiry and we will arrange for a suitably qualified installer to contact you.

Solar panels are connected in series to create long ‘strings’, just like daisy-chained Christmas lights. Each string of panels is connected to an inverter which transforms the DC electricity produced by the panels into appliance-friendly AC electricity.

Safe solar installation and maintenance

The facts around fires started by DC solar systems speak for themselves.

Some solar installers may not wish to risk losing a sale by acknowledging the risks involved with conventional, high voltage DC solar systems.

We recommend you ask your installer about safer solar technologies (microinverters and DC optimisers). If the installer doesn’t offer these options, then we strongly suggest you seek quotes from alternative suppliers who understand both the risks and the full range of technologies available.

The Clean Energy Council and various Electrical Safety offices in Australia recommend regular inspections of solar systems (at least every 12 months) to reduce the risk of a fault.

While inspections can reduce the likelihood of a DC arc fault, an inspection cannot prevent DC arc faults. An inspection can only pick up obvious faults. It cannot prevent rodents biting through the cable insulation or water entering any part of the circuitry or simply detecting corrosion of any of the various DC cable joints – all of which can cause a solar fire.

If you have moved into a new home or business premises with rooftop solar, or you are unsure, have it inspected immediately to determine what type of solar system you have and whether there are any obvious safety risks.

Most experienced solar installers in Australia are at least aware of safe solar technologies, however around 70 percent of all solar systems installed in Australia still use conventional DC solar technology. Safe solar technologies are growing in popularity as the risks associated with DC solar systems become more widely understood.

Current Australian standards do not prevent solar companies from installing conventional DC solar systems with unprotected DC cabling. These systems are common because the components cost less to buy compared with DC solar systems with DC optimisers or AC microinverter-based solar systems.

In other countries around the world, standards are already changing to prevent the installation of these systems. It is likely that Australian standards will also change over time to improve safety standards and encourage safer solar technologies to be used in all systems.

In the meantime, it is a case of buyer beware.

Energy storage

Many energy storage systems utilise high voltage DC and these systems are susceptible to dangerous DC arc faults just like conventional DC solar systems. There are energy storage systems available that only use low voltage DC and are compatible with safe solar technologies.

Not all energy storage systems are designed to provide power during a blackout. Simple systems store energy during the day and allow you to use this energy at night to reduce the amount of electricity you need to purchase from the grid. More expensive and advanced systems can enable you to access the energy stored in the battery during a power outage.
However, while inspections can reduce the likelihood of a DC arc fault, an inspection cannot prevent DC arc faults. An inspection can only pick up obvious faults, it cannot prevent rodents biting through the cable insulation or water entering any part of the circuitry or simply detecting corrosion of any of the various DC cable joints – all of which can cause a solar fire.

If you have moved into a new home or business premises with rooftop solar, or you are unsure, have it inspected immediately to determine what type of solar system you have and whether there are any obvious safety risks.

Safe solar investment and payback

Yes, in the same way that seatbelts and airbags add to the cost of cars, safe solar technologies cost more than cheap DC solar systems.

There are other benefits of safe solar systems that justify the additional cost, including higher energy yield and greater overall reliability.

Based on current electricity costs, a high-quality solar power system using safe solar technologies has a typical payback period of between three and six years. A system like this would be expected to operate for at least 20 years.

SOLAR FIRES

Solar system fires have been blamed on inferior design, low-quality components, poor installation or all three of these factors.

The heart of the issue is that the systems that fail, are designed to operate at up to 1,000 volts DC, which is inherently dangerous.

Any fault on a high voltage DC circuit can result in a dangerous DC arc.

The DC wiring in conventional (string) solar systems, runs under the solar panels on the roof down to the inverter. The circuit in a typical 4kW DC solar system has about 30 separate connections. Each of these joins is a possible point of failure. A 100kW system could have 350 potential failure points.

A DC arc fault occurs when there is a flow of electrical energy through an air gap in the wiring. Although air is regarded as a poor conductor, a high potential (voltage) difference between contact points in close proximity, can cause the air molecules to break down and carry a charge.

The arc fault and resultant fire is intense, generating enough heat to melt copper, which has a melting point of 1,085°C.

Poor installation can be a factor but there are many possible causes of a DC arc fault irrespective of the quality of the installation. The two main causes are compromised insulation on one or both of the DC cables or, when a connection in the DC circuit is compromised.

Possible contributors to a DC arc fault include loose connections, corrosion, water ingress, animals (insects, rats, possums, birds) damaging cables, extreme weather events, accidental (crawling through a roof space, drilling through a wall to hang a picture) damage, intentional damage or vandalism, failure of plastic fitting and enclosures, and moisture build-up within sealed components.

There is no way to eliminate all the potential causes of DC arc faults in a DC solar system as it is the high operating voltage itself that creates the risk.

As the system ages, faults will inevitably occur, and when they do, dangerous situations leading to DC arc faults can occur.

If there is smoke, arcing or fire, call your fire and emergency service immediately.

If you suspect that your solar system isn’t working correctly or have any other concerns, you should also notify the company who installed the solar system or your electrician and request that they attend the site to conduct a thorough system check.

EXPLORE THE BENEFITS OF SAFER SOLAR

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FIRE SAFETY

Select the right safe solar solution and protect your home from fire.

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ENERGY FREEDOM

Reduce your reliance to the grid and the protect against rising impact of energy prices.

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INVESTMENT SAFETY

Safe solar solutions typically harvest more power over the life of the system.

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