Well, grid feed-in can lead to faster repayment and smaller bills, but it's only 20-25% of the electricity price, so generating enough to be in credit relies on paying off the usage you have when the solar isn't generating enough for storage, or to offset your grid usage.

i.e. If you use 10kwh from the grid, and export 40kwh, you should get credit on your energy bill, but it's never that ideal, and some of the providers cap the export to 5kw/h for residential solar.

Most Australian energy providers have flat rate, some are on smart metering with peak/Time of Use rates;

The benefit of a battery isn't as immediate if you're not on peak rates. For those states which do have Peak/ToU rates, there are calculators that can show the amounts saved over 10-20 years, but it's still around 12 years to pay off a battery and solar install with the current pricing, not enough to cover the warranty or the useful lifespan of a battery in the same period. i.e. In 6 years, we'll have a next generation Powerwall or a competing technology, or something even cheaper, etc to store energy.

The solar rebates mean that even a smaller solar system is cost-effective in a smaller payback period.

The amount of the rebate has started to reduce, but a 4kw solar install will have a rebate around $2400 AUD ($1800 USD) off the price of the install, which usually comes to around 25-30% off the total cost of $5000 AUD, around USD $4200.

Prior to the half-price chinese panels coming into the market, the break-even was around 8-10 years, even with rebates. Cheaper panels have reduced the payback window to 4 years in some cases, even if the actual performance is not even close to the system's size,

ie. their real-world performance might only be 3.4kwh on a 4kw system, and the real-world payback might be closer to 5 years, due to changes in energy pricing affecting the returns, but also handling the problems like difficult installations, replacing/handling faulty hardware, or having to service the system if it fails in Australian weather conditions.

You can also find aggregates for these prices on sites like https://www.solarchoice.net.au/blog/residential-solar-pv-pri... which contrasts costs and pricing across states, and also accounting for variables like labour and electricity pricing, etc. Most solar systems with the rebate can be USD $3k to $5k for a smaller home install, and the system can be paid off within 4 years, 5 years if you want reliable parts.

Energy Pricing in Australia depends on state and providers, but is around USD 20c per kWh depending on state and supplier, with some areas having flat rate, others requiring net metering and peak/offpeak times

There's also a grid connection cost of USD ~70c/day, while Feed-in of solar PV generation is around USD 6c to 10c per kWh, which will probably drop to 5c/kWh in July. An earlier solar generation scheme had dual/gross metering and USD 45c/KWh feed-in rates, but this was discontinued in 2016.

Add to this, residential systems often have to get special approval from their energy company for things like 3-phase solar installs, require limiting exports to 5kwh, restricting to 90% output for Grid stability, sic. etc.

There are no rebate programs for the batteries, and there's a cost hike for importing the Tesla Powerwall 2, for no particular reason.

Compared to the AUD $9,000 to $11,000 AUD cost for the PW2 install, and despite it being better value, there are smaller, but similar LG Chem RESU batteries, which are more affordable and easier to obtain.