Just thinking if it is worth having a system maybe you blokes that have one could give me your thoughts 

This is a very interesting topic that should be explored more. 

Put 4 kw on the roof about 2 years ago power bill in credit all the time should pay for it self in one more year 

How can ya tell a shonky solar installer/business from a decent one? Word of mouth ... and hoping the bloke you contract to doesn’t turn up at install in a clapped out old Ford with non-English speaking mates who came by the kit off the back of a truck, therefore warranty discussion is a non-discussion?

I put a 2kw system up a few years ago, feed in is only 7.5 cent's (missed out on the high feed in ) and cost from grid about 19 cent's so I  get less than half. Convert all lights to led to cut costs, if you can pay up front with no finance and forget about how long to recover the cost and just concentrate on the savings off each bill it works. Inverters make the difference more than anything, cheap shit ones can cost power and be dangerous with larger systems feeding high DC voltage to them so watch packages offered by some companies and do research on inverters be prepared to pay a bit more for a better one for safety and efficiency. Battery storage will give back more but cost more as well and battery life could be an issue creating on going cost for replacement, how many rechargeable things have you had that only last a year before the batteries die and make it useless unless you replace them so with storage systems costing so much, having to replace every 5 or so years would mean you would never be able to recover the cost. Because of the shape of my roof not all the panels face north so later in the day some fall into shadow and are less efficient and this can effectively shut down the whole bank meaning no power from half the system for part of the day. I have an inverter on each panel feeding ac voltage into the system so if one is in shade the other 7 still work independently, down side is difficulty in installing storage.

I had a 3Kw system with a 4Kw inverter installed in 2004, $18,000.
all facing north, we were paying $800 a quarter, now we range between $100cr to $200 bill, depending on estimate or actual read
we get $0.55 tariff

we have had 1 inverter replaced a year in, near 12 month threatening the installer, contacting ombudsman, till finally, contact the manufacture, they sent a new one and paid the electrician to install it

I know a couple guys that have 10Kw systems on their homes, they are on good money

some great info here fella`s it touches on all the concerns I have had . I am in NSW & gone with a mob called Space Solar their installers are employee`s of the company not sub contractors . I have chosen a 3kw system  for my shoe Box with Canadian panels & a Sun grow inverter made in japan but has a good record here in Oz European ones are another couple hundred bucks . I have a flat roof so will need a tilt up frame & have  a good unrestricted North facing direction. Ferrett62 not long winded mate I think your taking about Micro inverters that go on each panel converting to AC before it goes into inverter I asked about them but would have put another $1800 on the price will have to hurry up & wait till new year for install so will have a chat with my Retailer see what they are offering .your right about the batteries Cropduster they are advancing but not an option at this point Thanks a heap for all ya replies 

installed 4.2 kw system in 5 years ago. Summer is always a credit. Spring & autum $100- $150 bills. Winter sucks. Feed in tarrif 28c per kw till next december. 

We have the biggest system Ergon will approve which is 6kw from memory. Thats 24 panels on the roof. It took them ages for Ergon to hook up the meter and theres a possibility the panels were switched on and wound the meter back. Since the new digital meter went in, we've used a shit load more than has been put back into the grid. There's a possibility that could be because the how water system is on the way out but we were gone for 3 days last week and came home to 150kwh used and 40 produced. That seems a bit strange to me. 

I remember the day we got the solor on, the old meter was spinning backwards, got some good credits, we went over seas for 6 weeks and came home to a great bill

we thought this solor is shit hot, then the new meter was installed, still get the odd credits but nothing like before