Noosa Electric Co provides an Advanced On-Grid AC Solar Solution suitable for Australian homes and businesses. We service Noosa and surrounding suburbs. On this page, we provide information to help you understand how AC solar works and how it is different from other solar approaches.
Solar – A Broad Overview
In a typical residential solar installation, the sun’s energy is converted into electricity. This is done by solar panels using the (PV) effect. Panels convert solar energy into DC (direct current) electricity. This is then converted to AC (alternating current) for practical use. While all of this can be done with a DC or an AC solar system, they go about it in different ways.
DC and AC Solar Differences
1. Type of Circuit
DC solar arranged in a ‘series’ circuit has all electrons flowing through the same circuit. Connected panel to panel, this circuit leads electricity as DC to a single inverter, where it is transformed into AC suitable for use inside the home.
An AC Solar installation works in a different way. Each solar cell has a micoinverter which converts DC to AC at the solar cell. By working with AC and enabling the solar cells to operate individually, a range of advantages are unlocked in safety, efficiency, scalability and longevity.
2. High Voltages on the Rooftop
In a DC Solar system, the series circuit can lead to high DC voltages on the rooftop. This is due to the fact that the solar cells are linked together in series. This can result in DC voltages of up to 600 (Residential) – 1000 (Commercial) Volts DC on the roof.
In the event of the circuit being compromised due to any number of reasons (rodents, environmental wear and tear, water ingress, etc) this can result in high voltages of DC current arcing which can cause injury and fire. 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.
An AC solar system doesn’t need high DC voltages – its DC voltages never exceed 80 volts. This makes for a safer solution.
3. DC Isolator Switch
The DC Isolator switch is one of the most common points of failure in a DC Solar system. Required by law in Australia, the purpose of this switch is to separate the DC circuit from the rest of the house. Although the intention is to make the system safer, over time the failure of these switches and subsequent exposure to the environment is a leading cause of failure in DC solar systems.
In an AC solar solution, there is no need for a DC isolator switch because there is no high-voltage DC circuit. Microinverters transform DC to AC at each panel, and the AC voltage on the rooftop is much lower because it is operating on a per-panel basis, as opposed to the combined effect in a DC Solar series circuit.
4. Performance in Partial Shading
In a DC solar installation the performance of the whole system depends on the performance of each individual cell. If a cell is shaded, this impacts the performance of the entire array, reducing the output. In an AC solar system, cells work separately from each other. Any shading only impacts the individual cell, not the entire system.
4. Centralised VS Decentralised Inversion
Another important distinction between AC and DC solar is the impact of a single vs multiple inversion points. In a DC solar system, the whole system relies on a single inverter to transform DC to AC. If this inverter fails, the whole system goes down. This single point of failure doesn’t exist in an AC solar solution. Here, the inversion happens at the panel with a microinverter. If it should fail, only a single panel is impacted – the rest of the system won’t be affected. This creates a more robust system that isn’t dependent on a single inverter.
5. Scalability
Scalability (the ability to change the size) of your solar installation is an important consideration. The installation that works for you now may not work for you in 5 years time. A case in point is electric vehicles. If you transition to an electric vehicle, the need to charge your car would change the profile of your energy usage requirement.
DC solar installations are inherently less scalable than AC solar installations. Adding additional solar panels is only possible as long as the single inverter can handle the additions. It may be necessary to upgrade your inverter to accommodate extra panels. In comparison, AC solar can be scaled as needed. Panels can be added, or removed, as required without compromising the rest of the process. This is achieved by microinverters transforming DC to AC at the cell rather than at a single inversion point.
