January Power Bill – Huge Aircon Usage, Tesla Charging, Bushfire Haze and more!

Tesla Powerwall 2's mounted

Well January is probably the biggest month for our family when it comes to power usage. The temperatures are hot, the kids are home and I’m usually off work for a while, this all adds to higher consumption.

It has been a few months since I have done these posts, purely because they take a great deal of time to put together. However, thanks to Whirlpool user memeka, they’ve put together Powerwall Monitor which uses Docker, Influx DB and Grafana to create some great Powerwall graphs that help me get this data easier!

Now, some assumptions before I get into the data. My feed in tariff is 21c/kWh which arguably reduces the benefit of having battery storage. I am on a TOU plan with AGL but the data isn’t easy to split based on TOU rates so I’ll work on AGL’s single rate plan of 29c/kWh. Daily supply charge is not factored in but GST is.

Powerwall Monitor Data

Ignore utilization figure, that’s designed for day use. Utilization for month was $49%
  • We consumed on average 38.7kWh per day
  • Powerwall efficiency remains at 87%
  • If we didn’t have solar we would have spent $343.12 for the month or $11 a day for power!
  • Thanks to solar and battery storage this dropped to $27.01 for the month or 87c per day!
  • If we look at pure battery only savings, factoring in my high feed in tariff and efficiency losses it contributed to $19.09 in direct savings
  • Roughly a third of energy came from solar/battery/grid/

TeslaMate Charging Data

TeslaMate charging stats for same time period
  • 183kWh of Model 3 charging was done at home during this billing period or approximately 15% of entire consumption
  • All charging done in off peak period (Powerwalls are configured for TOU rates so discharge rarely in off peak period)
  • Costs of Model 3 charging in January was $28.49
  • This will inevitably rise when free supercharging is exhausted
  • During this time period I did 78 drives for a total of 2841km.

Actual AGL Bill

Actual AGL bill for the month of January
  • Total bill for the period of January was $17.28
  • My account remains in credit of $347.75
  • Feed in for this month was low, due to many days of low solar production due to bush fire smoke/haze

Overall, I am super happy with having to “pay” just over $17 for what was over a megawatt hour of usage for the month. Solar really does save you money and I did see some benefit in battery storage during January!

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Author: Adam

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