Garantee on the life of the inverter

 If, as you say, you don't use much during the day, you will still see a lot of difference--there will be a difference, as you are feeding back into the system ( and getting paid at the princely sum of 7.1c/unit ), as well as covering your firidgs, freezers, etc.  You'll find you'll be able to run your a/c during the weekends/scholl holidays when you are at home for virtually nothing. We run our refrigerated A/c a lot more than we used to in summer ( live in Kalbarri), and bills are still about one third of what they used to be in a hot summer. Of course, you need to turn them off as the sun gets low. Cooler times of the year, and shorter days, see our bills down by half. And we both work, although I'm home half the time, FIFO roster.

There are some things you can do to maximise use when you are generating from solar, such as run things like dishwashers and pool pumps only when you are getting solar input. This is all well known. Don't go for a cheapie inverter: and I would also advise you to get one which is battery storage ready, or at least easily adaptable when the time comes. They don't all do it. 

Battery IS NOT worth it at the tic. Solar is though get a known brand battery compatible system. Battery ready inverters are quite expensive and in reality, if you get a system now and don't plan on a battery within the next 5 years, it is probably not financially viable to get a battery ready system now as the price will come down and the quality will improve over the next few years.

Batteries currently have a 15 life and 20 year pay back so easy to see where you are better off.

For us, (2 adults and two kids) with a 6.4kw panel system running into a 5kw Fronius system, our bills have halved. Our neighbours are retirees, have the same system, and they get money back. They have a pool too.

 I am thinking of getting one too but just not sure where to start. Will be installing a reverse cycle ducted air-con together at the same time.

 Ive had my solar panels for about 4 years my bills were around 400 before they now range between 40 and 130 dollars i am very happy with the savings 

So, it does seem to be worthwhile then.

Time to start shopping around.

Thanks everyone for the input. 

Have a look at www.solarquotes.com.au  Some pretty good info on there re brands, what you need size wise, etc.  You can also get comparative quotes from different companies.  I found it really usefull for a numpty like me who knows nothing about solar. 

I was sitting on fence for a year or so , considering , looking etc.

Bit Bullet in January and got system installed Feb. WP needed to come out and change the old meter, I wasn't supposed to turn system on but wanted to watch the spinner and see what happened when solar on and effect on useage not technical but certainly good fun).

All on at same time- 2 Split AC systems and pool pump ,fridge x 2 , freezer x 2 running plus washing machine and TVs all going.

Spinner stopped spinning and nearly was trying to go backwards ( that's why they want u to change to new electronic meter,plus measures what you put back in to grid).

As an FYI was using around 24 units a day / bill around $450 pre solar and that was being tight with pool running time and minimal aircon use. Feb/March post solar bill $163 . Breakdown of bill $166 consumption from grid ( night time) $56 for supply charge ( cant get out of that one) but received $81 cr for what fed back in to grid. This was even with longer than before aircon/pool pump run times than normal during day ( set the timer and let sun pay for the cost)

Look at quality panels and inverter ( I didn't go cheapest ) , get hybrid inverter which you can connect to battery down track ( I had same thoughts as you , not worth it currently). Change your usage habits (set dishwashers and Washing machine/pool pumps/air cons etc to run during day by timer and not at night). You can see on inverter when best times are by how much its pumping out KW wise .some people monitor via apps etc , I have a life ! I did get a plug in monitor for around $120 maybe , you plug in to powerpoint , plug appliance into it , set it and you can see how much power everything uses for KW perspective / $$ perspective over a set time ( ie a day or week so you can work out fridges use as they cycle). That way worked out whats using most power and when to run stuff in winter if cloudy and system not producing 5KW. Mine isn't shaded by trees at all and gets full sun for around 8 hrs day min in summer. So you need o consider how its orientated ( I have mine split in to two different roof lines) and shading from trees and houses.

Hope that helps you / others.

 we had Koala Sola rinstall ours down here in Busselton. 
They are based in canningvale and we got the biggest system we could at 6.48kw

it cost me a shade over 4k installed, the cheapest quote i received by over a grand and the workmanship was fantastic and they work brilliantly.

We are currently producing much more than we are using so we are ready for battery but waiting for the price to drop a little. 

as stated above is a few small costs initially with smart meter but certianly worth the investment. probably the best time to get it installed price wise at the moment.

we have a zeversolar inverter (sma brand, probably comes out the same factory anyway) and canadian soalr panels. 

they all have long warranties nowdays and will pay themselves off with 3 years so youll be infront.

imo your mad if you own your house, have good sun not alot of shade and dont have them

 Don't install them until you have moved in. Wait for a few bills and see what your consumption is like then size to match. No real savings in installing during construction. Stick with Fronius on the inverter front. Panels, heaps out there. Stick with Tier one modules. Trina, REC, Qcells etc. Make sure your installers are using compentent guys/girls on your site. Thats the easiest place to cut corners for a solar Co. Otherwise, it is a more than worthwhile investment and geenrates energy way cheaper than current grid rates. 

Re batteries. No, not close to worthwhile....yet They will not last you 15 years (well not with any efficiency), more like 5-10 years. Wanrranties stating 10yrs and above have a LOT of clauses. Essentially your lead acid/Li-ion etc batteries have finite cycle life (number of charge/discharge "cycles"). The more you charge and discharge them, the shorter their life. They can't be fully cycled (so you can't discharge them 100%, usualy only around 60-70%) and they are subject to thermal runaway (have a google seach of Li-ion going up in flames). Don't get me wrong, they are great products for certain appplications and there are ocassions that it is financially worthwhile now but not really in a residential metro setting....yet. More like areas with regular outages, sites with capacity constraints, high peak rates etc. Give it a couple of years. 

Do keep an eye on VRB's (Vanadium Redox Flow Batteries). They are an Aussie invention and (the right ones) have a life span that will exceed 20 years. Plus at end of project life they still retain the value of the electrolyte which is around 30% of the cost of the unit. They can be fully charged and discharged as many times a day as you like and they won't degrade and then have to be chucked in 5 years like your Li-ion units will (think about your laptop and phone batteries). The negative, they are still pricey and not easily accessible. BUT, they are they shit and will be big in the coming years!

Bit biasedand a bit long winded there but all of that info is easy enough to find online and workout. 

 Zamien has nailed it for you mate,

I install for a living at times and yep there is a shit load of info that can become oevr whelming.

Basically my advice is, Tier 1 panels with a 5kw Fronius inverter...

Even if you only go say 3 kw of panels you can be sure you will want to ramp up one day so to save the cost of buying another inverter go the biggest they allow which is 5kw.

I've also gone as many panels as i can, its working a treat for us and in 4 years ( our pay back period ) it will be $1500 per year back in our pockets...

We dont go crazy with worring about changing how we live either, we basically live like we did and save so dont think you have to be a Nazi about your power usage, just common sense really.

You'll get a log in thingo on Fronious site ( if you get a smart meter with the Fronious ) and you'll soon see when the microwave zaps 2000kw from what you were putting into the grid when you are checking the app to see how much its cranking!

Brilliant info guys.

 the solar rebate isnt what it was , my brother inlaw is still on the 47 cents a kw rebate (but it runs out in 2 years ) in his case it was a good deal , me i am geting 4.5 cents a kw because i got in late , personaly i wouldnt do it again , re battery technology , its geting better , but as with  all new stuff it will only get cheaper in the futer 

In my opinion get the biggest inverter you're allowed (5kW) with the most solar panels you're allowed (6.6kW) and don't worry about the battery for now.

The inverter and installation certification process keeps changing over time and older inverters get dropped off the CEC approved list. That means that you can't always get approval to add extra panels to an older inverter even if you bought the inverter with plans on upgrading in the future. If you wait longer than 5 years to upgrade, then the odds are the inverter won't be on the approved list any more.

Doing the install in multiple stages also adds to the overall cost because the installer has to come out multiple times. With the price differences between bigger and smaller systems it works out cheaper to just do it all at once if you can.

With the batteries, you only need a battery ready inverter if you want DC coupled batteries. If you go with an AC coupled battery (like the Tesla powerwall) they have their own internal inverter instead of piggybacking on the solar inverter. That means they can work with any solar system and spending extra money on something that is 'battery ready' might not be necessary. There are some advantages to DC coupled batteries vs AC coupled though, but the differences start getting pretty complicated.