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Hi Peter,
In mid August 2008 I had a 2KW array installed. With the thought in mind that I may want to increase the capacity down the track, I specified a 3 KW inverter. The difference between the initial cost of a 3KW inverter relative to a 2KW inverter was only about $400.
I also specified the installation of a data logger with my inverter. This allows me, at any time, to take my laptop out and plug into the data logger and download my data. The software that came with the data logger allows me to look at a graph for daily performance with data points every 10 mins or graphs for monthly or yearly performance.
In May 2009 I added another 1KW to increase my array to 3KW.
At the end of Aug 2008, about 2 weeks after the installation we received a 3 monthly power bill which was $406.
My next power bill dropped to $60 and my 2 most recent power bills have both been in credit. I am still waiting to have a gross feed in tariff meter installed, so at the moment I am still only being paid on what I export and not my total output.
From mid August to end of Dec 2008 my 2KW system produced 1.7 MW/Hrs.
From Jan to Dec 2009 my system, which was upgraded to 3KW in May 2009, produced 5.278 MW/Hrs.
It is easy to do the math for what to expect at 60c/KW/Hr. Based on my 5.278 MW/Hrs as a min output, this figure will obviously be considerably larger after a full year as a 3KW system. However an absolute min return of $3,166 would be expected.
I did a considerable amount of research prior to deciding to do this. I selected Sharp 2160 W NU-SOE3E panels. All Solar panels are designed to perform with a tolerance eg; +/- 5%. I have found that with my panels, peak performance is often more than the design ratting.
Let me say at this point that I have absolutely no connection with the Sharp company and my comments are based on the extensive research done prior to installation, plus the monthly data download that I have done from from my data logger since the initial installation.
There were other Solar panels that were cheaper than what I chose, but I looked at it as a long term investment and chose what I thought would prove the most efficient over time.
I live in Broken Hill NSW, the roof of my house is a hip roof and runs NNW to just East of South. I had my array installed on an angle across my roof so that is running East / West but tilted to the East.
A point to remember; Solar panel performance is de-ratted as the panel gets hotter. This means that it is vital to have the panels mounted at an angle to the surface they are mounted on, so that there is good airflow under them to reduce this heat build up of the panel. This is why Solar panels work so well in space, it is much cooler.
Have attached a pic of my 3KW array, note the angle across my roof to make them East / West and also the angle to the roof to get good air flow under them. The panels, for max efficiency need to be tilted to the Sun at whatever your local latitude is. Out here in Broken Hill that is near enough to 32 degrees.
Hope this is of interest.
Regards
Trevor
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