With any electrical installation, safety is always the highest priority. Our advanced AC solar solution comes with a range of advantages over DC solar in a string configuration, and improved safety is one of them. On this page, we look at the two main ways that this is achieved.
Do You Know About AC Solar?
AC Solar is an advanced solar solution for Australian Homes and businesses. It holds advantages in safety, efficiency, scalability and longevity. Noosa Electric Co installs AC Solar solutions in Noosa and surrounding suburbs.
A fundamental difference between AC solar and DC solar in a string configuration is how they transform DC to AC:
DC solar: transforms DC to AC at a single inverter
AC solar: transforms DC to AC at each panel
You can read more about this process here. What’s important is that with AC solar, it does away with two disadvantages of the DC string system:
- No high voltage DC on the rooftop
- No need for a DC isolator switch
High DC Voltage on the Rooftop
In a DC series circuit, each panel added to the system increases the voltage of the circuit. This creates high voltages of up to 600 (residential) – 1000 (commercial) volts on the rooftop. High voltages in conjunction with any type of compromise in the circuit are dangerous and can lead to DC arcing, fire and injury.
According to the Safer Solar website, two fires caused by DC-related faults in solar power systems are reported per week in Australia, and this number can be expected to rise as the rate of installations increase and systems age.
There are many reasons why an installation may fail:
- Loose joints due to poor installation
- Loose joints due to poor quality connections
- Corrosion of joints over time
- Insulation degradation over time due to UV exposure
- Insulation cracking over time due to changes in temperature (hot – cold)
- Degradation of insulation due to aging
- Damage to insulation by rodents, insects, birds
- Damage to insulation during installation
- Damage to insulation by future building works
- Water ingress to cables, conduits.
- Water ingress to DC isolators from poor installation
- Water ingress to DC isolators due to degradation of seals over time
- Water ingress to inverter
- Water ingress to solar module or junction box
(SRC: AC Solar Warehouse)
AC Solar – A Low Voltage Solution
In a DC solar series circuit, each panel added to the system increases the voltage of the circuit. AC solar works differently. Instead of carrying high-voltage DC to a central inverter, AC solar microinverters work on a per-panel basis, producing a low individual voltage of between 48-60V, even less than the voltage of an electrical fan. With no high voltages on the rooftop, a safer solution is created. (SRC: Enphase)
DC Isolator Switch Failure
In Australia, in a DC solar installation, a DC isolator switch is required by law between the solar panels and the inverter. Its purpose is to switch off DC current if necessary for safety reasons. Unfortunately, the DC isolator switch is a common point of failure. Failure of this component may result in DC arcing, which may cause injury or fire.
In an AC Solar system, there is no need for a DC isolator switch. Because the transformation from DC to AC is done at the panel, a DC isolator switch isn’t required. By removing the need for this switch, a simpler, safer solar solution is created.