What is AC Solar?
Conventional direct current (DC) solar systems consist of a number of solar modules wired together in series configuration to create ‘strings’ of modules, with a combined output voltage typically between 100 and 600 volts DC. This is then fed into a single large inverter, which converts the voltage to 240 volts AC for connection to the electricity distribution system.
Alternating current (AC) solar systems use microinverters (small grid connect inverters typically rated at 200-250W to suit a single solar module) to convert the output of each solar panel directly to 240 volts AC. This eliminates the need to install DC cabling between modules or to install a large centralised inverter, and greatly simplifies the installation, monitoring and maintenance of the system. Microinverters provide all of the functionality of conventional string inverters – such as automatic disconnect and reconnect when the grid fails – and are required to conform to the same standards (including AS4777).
Advantages of AC Solar systems
Simplified system design, installation and maintenance
• Installation is easier and up to 20% faster than for DC solar systems
• Modules can be installed with differing orientations
• Systems can be easily expanded by adding any number of additional AC Solar modules at any time
• Systems are wired with conventional AC cables – no specialised DC cabling required
• No string sizes or DC voltage limitations to factor into the design
• Balance of system costs (enclosures, DC breakers etc.) are significantly reduced
• System commissioning and trouble-shooting is greatly simplified due to the data logging capabilities built into each module. Under-performing modules can be quickly identified and investigated.
Improved system performance
• Each module is individually maximum power point tracked ensuring the maximum energy generation from every module installed
• Any shading that occurs only affects the output of the shaded module, not a complete string
• Reduced wiring losses compared to low voltage DC systems
• Increased energy production of up to 25% has been recorded
Greater safety and reliability
• Eliminates the string inverter as a single point of total system failure
• If a unit does fail it only affects the output of one module and not the whole system
• System data is available at a module level (as opposed to a string or overall level). Continuous monitoring of each individual module via an internet gateway enables prompt response to any shading problems or component failure
• No high voltage DC cabling on the roof
• No DC circuit breakers or fuses required
AC Solar systems are ideal for residential and commercial installations and offer superior performance – particularly where shading or orientation issues exist.
AC Solar systems should only be designed and installed by licenced electrical contractors with appropriate Clean Energy Council accreditation.