Solar Generation in Perth

In March, with the June 30, 2011 deadline for maximizing the REBS rebate looming, and with Retravision coming on board to sell solar system’s (no, I was not foolish enough to buy from Unleash Solar or any of the other random solar companies that sprung up), I finally bit the bullet and purchased a 1.5kW solar electricity generation system for AU$3000. I would have loved to get a larger system, but I was quoted $22,000 for a 5kW system, and even a 3kW system would have costs $8,000, which demonstrates the very odd scaling in place at the time due to the government’s 5x REBS scheme.

After one year, the system generated an average of 6.8 units per day, feeding back in to the grid 1.8 units per day, which is saving about $700/year. This will pay off the installation cost in around 5 years, after which the system will save $700/year for the remainder of the ten years, making it an extremely worthwhile investment, after which it will save $500/year for the remainder of its life.

An important note is that the numbers change dramatically without the governments 40c/unit feed-in tariff. Removing that and reducing the feed-in rate from $0.48 to $0.08 results in a payoff period of 7 years, and then a $500/year saving. Still good, but considerably less good.

Three and a half years in, my solar inverter failed (you can see the zero generation period in November 2014 in the graph). Retravision promptly organised installing a replacement inverter (confirming my decision to purchase from a reputable company!). There was a brief outage shortly after the new unit was installed which I am still looking in to.

This page graphs the results of my systems generation. Note that my system is 1.5kW, and is almost perfectly situated on a north facing, nicely angled, unobstructed roof, so it is probably close to optimum for a stationary system. The graph shows units (ie, kWhs) generated each day, although I don't record every day so some readings are averaged over several days.