Single Wire Earth Return Distribution System
Because of Australia’s unique position of having a vast terrain to serve with very low population densities, the cost of universal 3 phase distribution has been prohibitive. Hence much of rural Australia is supported by a Single Wire Earth Return (SWER) system to deliver 240V single phase power, or by the ‘Two-phase 480V’ variation. (which is actually two regular 240V circuits coupled together). Instead of using 2 or 3 wires to distribute electricity, this system uses one wire with the return path through the ground. There are over 190,000 km of SWER lines in Australia. These systems are very much suited for :
- Sparsely populated rural areas or rural areas and villages with low demand e.g. each house has only lighting, TV, radio and maybe small single phase induction motors for water pumping
SWER lines, however, suffer from limitations due to over/ under voltage ad power outages. This system is single phase, so it cannot be used for three phase loads
Solar Power Installation in SWER System
Professor James Trevelyan, University of Western Australia wanted to install rooftop solar system in his rural property powered by SWER line in Crossman, Western Australia – about 120 km from Perth.
On the primary of the transformer there is only one wire ( 12.7kV phase to earth) and on the secondary side there are 3 wires: +240,0,-240 Volt two-phase wires; and one neutral wire.
Regen Power designed and installed a roof top solar power system based on the customer’s power needs, available roof size, orientation and other factors. The system consists of 20 x 260W GCL solar panels and 2 x 2500W SMA inverters. The present system does not use batteries. Regen Power can also offer low cost solar + battery solutions for SWER line applications.