Since May 2017 the author is hosting an older 3kWp solar system, a new 5kWp system (both are working on separate inverters in parallel) and a 10kWh battery. Since then I’ve been accumulating credits in my account with ENOVA energy – they are getting bigger and bigger every month, currently showing $900 in credit.!
Since installation, I’ve had 2 days where I had to buy grid energy due to abominable weather. I had another 5 or 6 days when my solar hot water system was broken that I had to buy Controlled Load power as well -grr….. But the generous 16 cent per kWh feed-in tariff ENOVA pays me for my excess solar power makes me come out ahead.
Read about my experiences for yourself here: https://onestepoffthegrid.com.au/first-month-solar-battery-storage/.
For larger families it may not be quite so advantageous, but it is entirely feasible to reduce a family power bill close to ZERO for an investment of less than $15,000*. With that, the rate of return is somewhere in the range of 10-18%, depending on how much energy you use and how power prices develop in the future. Try to get that much interest from your bank!
* We are assuming a largely unshaded roof here and relatively energy efficient devices.