Question: In Brisbane, Australia what’s up with hotwater?
Method: These data are mostly from Brisbane houses from March to September 2023. Units are kWh/day mostly. Typical family of 3 but varies.
Answer: read on.
Does it matter?
The best unit costs 1kWh/day and the worst 9kWh/day. These have similar usage. That’s about 30c versus $2.75 per day. That’s about $100/year versus $1000/year.
So yeah, it matters.
Hit me with the numbers!
What does that mean? Let’s take a few:
- hfs01a: Solahart 300L on-roof solar, no timer. Two kids. 1.8kWh/day ($200/year). That’s pretty good.
- hfs02a: As above, maybe 30% less hotwater use. 0.8kWh/day ($100/year). That’s great. This is the effect of a $50 timer. More on timers below.
- roop / arn: 300L storage units. 3 occupants. Poor insulation. 7kWh/day ($750). That’s expensive.
Geez, too much information. What’s the answer?
- Buy a solar hotwater system with tank on roof and add a timer.
- Expensive but apply for rebate. It will payback in 3 years.
- Solar pumped or heat pump
- Expensive but apply for rebate. It will payback in 6 years.
- Use a electric storage
- It’s cheap to buy but expensive to run
- Insulate your pipes and tank well.
- Keep electric storage if you have solar. Add a timer.
What was that about the timer?
If you have a solar hotwater system, it needs a timer: