[thedays]

Yes - the regulated offer is capped at 24 kWh per day but some retailers such as Globird and CovaU are offering plans which include up to 50 kWh per day of ‘free’ electricity. With a large enough battery and inverter you could just end up paying daily supply charges of $1.65-2.20 per day.

[rsanek]

Critically, that cost excludes the amortized amount the batteries will be over that period. And if you're cycling them every day like this, they're not going to last more than 15~20 years.

[wolrah]

> And if you're cycling them every day like this, they're not going to last more than 15~20 years.

You can't make a blanket statement like that because it depends on a lot of variables about their specific battery system and power needs. If you have just enough battery to get through a normal day so you're running them top to bottom every day then sure, those are likely to have a relatively short life. If you've set up your system with extra capacity to support extended total grid outages and/or bad weather now your normal days might only be cycling from 80% down to 60% and back. Of course battery chemistry is also relevant, and a home battery system doesn't need to care about energy density or peak charge/discharge rates in the same way an EV might.

On top of all that, now that we're over 15 years in to mass-produced EVs we've learned that our battery life expectations were generally pessimistic. As long as the batteries are kept within a reasonable temperature range and not otherwise abused they tend to be in pretty good condition even this far in to their expected service life. Home energy storage systems are a lot easier on batteries than automotive use so as a general rule they should last even longer even with similar cycle counts.

[adrianN]

Cycling 50kWh of batteries daily seems like a very unusual level of consumption.

[Schwolop]

I'm in Australia, with Globird, and have their 3hrs free plus they pay $1 on days I don't use any grid power between the 6-8pm peak, and another $1.50 if I send them back 10kWh of the energy I was given for free during the day, during that peak. In winter, with bugger-all solar (maybe 5kWh generation if I'm lucky) I pull 10kW/hr into a 40kWh battery for those 3hrs each and every day, while also running the heating as high as possible to gain some thermal battery effect too. That 30kWh of battery charge is used up by late evening or middle of the night by fully-electric heating (RCAC split systems and a large ducted RCAC system), so the battery goes down to 5% where I stop using it except in the case of grid failure, and back up to ~75% each day. The idea that no one uses more than 24kWh of electricity each day is absurd - not only will I pull 30kWh to charge a battery, I'll also pull another ~30 or so just to keep warm. My house could easily use 100kWh per day if we heated it to a pleasant level instead of a warm-enough level.

The main problem, as Australians are no doubt aware, is that our houses are large and poorly insulated. I've done everything sensible already (ceiling + floor insulation, draft sealing, honeycomb blinds, etc) except paying $100,000 to double-glaze all windows, and it still feels like a tent.

Despite all this ranting, electricity is now effectively free in summer for me, and ~$5-8 per day in winter. Pre-battery it was in the ballpark of $10-25 per day. The battery should have a payback period of 4 years, but was heavily subsidized by the government. Due to how I'm charging and discharging it so regularly, I'm expected it might only have a 10yr lifetime.