Therefore, my standard quarterly bill will have $100 of supply charges in addition to any usage that occurs.
I am super lucky that I got on to PV when there was a large (unsustainably so) government incentive, so my feed-in rate is 54.6c/kWh (not including GST) which more than offsets my normal use since I am never home during the day and thus feed that all in, then use power at night at the 28.6c rate. I essentially get a negative bill as a result (told you it was unsustainable).
Nowadays, the feed-in for new contracts is just 6c or so, hence people now look to invest in using that power, or having battery storage.
The fact one person gets negative bills doesn't mean it's unsustainable. It's only unsustainable if it costs more in energy storage + standby infrastructure + your negative bill than it costs to run the usual energy production pipeline.
That may be the case, but it's unrelated to whether you're paid back or not.
It's unsustainable in that many people jumped on this deal, far more than forecast, and so they pulled it years ago. The government had essentially subsidised solar through feed-in tariff bonuses, but hadn't expected the volume of people who ultimately took it up.
It's also my understanding is that's not how the infrastructure works. It's simply not set up such that my feeding in could be sent arbitrarily to a storage point. Indeed, a colleague of mine was having his inverter trip during summer because his + many of his neighbours were all feeding in however none were drawing out. The grid was therefore being overloaded locally and all of the inverters were hitting their automatic cut-off points because of it.
So yes, in theory it could be sustainable, but this particular situation absolutely wasn't and if you were to get solar now, you would not end up making money off feeding in like I do. It's now purely to offset self-usage.
What sort of place are you living in? I haven't lived in NZ for 11 years now, but I recall heating costs of $100s/month in Winter (poorly insulated Christchurch housing as a poor student). Perhaps the high costs were due to high consumption rather than high unit costs... I didn't really pay attention to it at the time.
I'm in Auckland in a modern well insulated apartment. If I was in a normal nz house I'd expect to triple that, since we have a long distance relationship with insulation.
Around NZ$130/month for us, in Auckland. Four bedroom house, but it was built to 2015 code so it’s well insulated and double glazed, ambient inside is about 16C in the middle of winter, so it’s cheap to heat.
Couldn’t imagine living in one of the leaky sheds built before modern regs...
Hmmm, in VIC I pay $0.96/day supply and usage rates of about 16c/kWh. Maybe prices vary a lot by location, because the prices I pay bear no resemblance to those on the chart...
Possibly relevant: I do look at my usage and compare providers and I am with what appears to be the cheapest possible provider for me (according to https://compare.switchon.vic.gov.au, with smart meter data providing a very accurate basis for the comparison).
And having mentioned that, I thought that it had been a while since I checked... Seems I can get $0.72/day supply and 14.9c/kWh now, I guess it's time to change.
Supply charge: $1.10/day
Usage rate: 28.6c/kWh
Therefore, my standard quarterly bill will have $100 of supply charges in addition to any usage that occurs.
I am super lucky that I got on to PV when there was a large (unsustainably so) government incentive, so my feed-in rate is 54.6c/kWh (not including GST) which more than offsets my normal use since I am never home during the day and thus feed that all in, then use power at night at the 28.6c rate. I essentially get a negative bill as a result (told you it was unsustainable).
Nowadays, the feed-in for new contracts is just 6c or so, hence people now look to invest in using that power, or having battery storage.