Mick and Janet's  Photovoltaic Solar System.

Updated 1 Jan 2012


          Janet and I have a Photo Voltaic solar power system on our roof consisting of 10 x  BP 170w panels and a GCI1700E (Sunnyboy) inverter and 8 x 190w panels and another GCI1700E inverter..  The original system was commissioned on the 6th of Jan 2005, and the upgrade was commissioned on the 28th of August 2011, giving us a total of 3.2kw/h of generation. The supplier estimated our original system should generate around 2500Kwh per year based on our location and amount of daily sunlight (in Adelaide, South Australia). With the upgrade this should increase to around  4700Kw/h each year. You can see some photos from the Installation here.. In the picture below, the original system is the 10 panels to the left. The upgrade was the two panels on the right side of the bottom row and the six on the adjacent roof space.


Our systems performance..

The graph below gives a monthly breakdown of how much power the system has generated since it went live. The system makes more power in summer because the days are longer allowing more 'photons' to reach the panels compared to the winter months where the days are shorter, and generally more cloudy. 

  In this graph there are some interesting variations to the average. Jan 2008 was the greatest output month ever. It was the driest January on record for Adelaide. No rain, no clouds, just a 31 days of blue skies.  July 2009 was well above average as it was the driest July in many years, providing sunny winter days.  

Our system has worked as expected since it was commissioned. The supplier estimated it should generate an average of 2500Kwh per year based on our location and average amount of daily sunlight. The table below shows the total amount of Kilowatts produced by the system. To date its over 17 megawatts.

Year Production Kw/h
2005 2403
2006 2496
2007 2532
2008 2018
2009 2389
2010 2380
2011 2327 / 863
2012* -

*year in progress.


You can also see some other output info at PVOUTPUT by clicking either of the graphs below for the original system or the upgrade..



Solar Buy Back scheme...

When the original system was installed, the electricity company's would buy any excess power that your system generated during the day at the same retail rate as you paid to buy power from them. This was effectively a 1:1 system   To promote green energy systems, most State Government's in Australia legislated a formal buy back system for solar power that is exported to the grid.   In South Australia, a 'net' metering system was introduced in July 2008. Any solar energy that is produced by the panels is used by your house, but if you are generating more than you are consuming at any given time, the excess (or net) power goes out to the grid. The Electricity Trust of South Australia (ETSA) buy this power back from us at a rate of $0.44 per Kw/h.  On top of this the power companies add another 6c, giving you 50c for every kilowatt hour that goes out to the grid. To accurately measure the exported power, the ETSA fits your house with a two way meter. It measures power that comes into the house, and also what goes out.  In our case about half of the power generated each month is exported to the grid. This is because during the day our power needs are quite low so we have excess solar power.  

The good thing about the buyback is the excellent rate that is paid. We pay $0.25 for imported power, but get paid $0.50 for exported solar. As a quick example, if we export 4Kw/h during the day (4x $0.50 = $2)  we can then import up to 8w/h (8x $0.25 = $2.00) from the grid and not get a bill. If we import less than 8w/h, we will have a power credit.  Naturally we try to reduce our power consumption during the day to maximize the power exported to the grid.   You can make a big difference to your day time power consumption by doing simple things like turning off your computer when its not being used, and doing washing at night and hanging it out to dry the next morning rather than washing during the day. 

Changes to the scheme..

Unfortunately the buy back scheme has proven too successful.  Thousands of homes in South Australia have had solar panels installed, and the buy back of solar energy has cost the State Government many times what they had expected. Consequently a close date has been put on the solar buy back scheme. Anyone who has a system installed before the end of September 2011 will get the 44c feed in tariff until June 2028. Anyone that has panels connected between 1 Oct 2011 and 30 Sep 2013 will get a reduced amount of 16c, but only until 30 September 2016.  Full details of the changes can be found here. Unfortunately if an existing users adds more panels after the Sep 30 deadline, they will be disqualified from the 44c feed in tariff, and only receive the 6c from the power company.  It was the changes to the legislation that forced our hand to get another 1.5kw of panels installed before the cut off.   We know that over time our power consumption has increased as Janet is home during the day looking after our two children. As the kids get older, our power needs will increase further, so it really was a now or never option. .   




If you are looking at getting a solar PV system, please have a look at the green tech forums at Whirlpool. They have lots of great info on what is good, what is bad, and how much you should pay for a system..

We would love to hear from others who have an interest in Solar Power.  Please Email us if you have any questions or info to share.




Free Counter