You need to take the following into account over the full cycle of a year:
- how much you will consume
- when you consume ... ie more during the day or night
- your equation with grid connected solar becomes:
((kWh imported x retailer charge) + daily service charge) - (kWh exported x FIT) ... if you get a negative number then you are making money
- choosing your retailer wisely so that they don't rip you off on import rates
- Note the following import and export definitions:
- if at any instant you are generating more power from your PV system than you are consuming, then you will export to the grid
- if at any instant you are consuming more power than you PV system is generating, the you will import from the grid
- the ETSA import/export meter will take all this into account and record import and export continuously, so it is in your interest to consume as least as possible during the day when your PV system is generating power (ie. put the dryer, dishwasher, etc on at night)
Fact sheet from EscosaIf you had a PV system
- approved before September 30, 2011, you will get a guaranteed Feed in Tariff (FIT) rate from ETSA of 44c per kWh exported until 30 June 2028
- approved between 1 October 2011 and 30 September 2013, you will get a guaranteed FIT from ETSA of 16c per kWh exported until 30 September 2016
- approved after 1 September 2013, you will not receive a FIT from ETSA
All PV owners will receive an additional guaranteed minimum FIT from their retailer (they may elect to pay more if they wish) from 27 January 2012 to 30 June 2014 as follows:
- 27 January 2012 to 30 June 2012: 7.1c per kWh exported
- 1 July 2012 to 30 June 2013: 9.8c per kWh exported
- 1 July 2014 to 30 June 2014: 11.2c per kWh exported
So your total min FIT is ETSA component + retailer component ... in my case, this is now 44 + 7.1 = 51.1c per kWh exported from 27 January 2012.
The best way to maximise the benefit of a PV solar system is to consume as little energy as possible during the day (as you return on export is much higher due to FIT).
Since my 4.018kWh PV system was installed in May 2011, I have imported 2950kWh and exported 2722kWh, so my electricity account balance over the last 8 months is:
((2950*0.25)+128) - (2722*0.44) = -332 ... so I have made $332 in that period
Dedja's PV statsIn the same corresponding 8 months prior to installing my PV system (May 2010 to Jan 2011), I would have paid approx $2000.
Therefore, I am approx $2,332 better off ... and that is only after 8 months.
Now to ensure that seasonal adjustments are taken into account, I need to wait until I have 12 months of solar before trying to work out a payback period with any accuracy.
But based on extrapolating the figures so far, my payback would be less than 4 years.
My best advice is to get a power usage monitor (apparently you can hire from some councils are even your retailer) so that you understand your power usage patterns, then create a great big dirty spreadsheet and create scenarios to take into account predicted retail power increases, and you estimated usage.
Only after doing all that (which I did) would I even contemplate getting a PV system over 1.5kWh
So after all that, only you can answer the question of whether it is worthwhile to get a PV system now if you expect to sell your house in 5 years. My gut feel is that any payback on a system will be negligible over that period when you take into account the capital gain of your house as an asset.
I don't expect to be selling my house in the next 10-15 years, and if I move I will probably retain it as an investment property anyway, so the investment in a PV system is well worth it.
With any luck some of this will make some sense.

Dunno, I’m just an idiot.