Hi from north east plague state

[Prof Tournesol]

I've had a long-term interest in sustainable living and renewable energy. My wife and I moved here from Melbourne around 4 years ago, having dismantled and recycled the original home on the site and replaced it with a prefab home. It's not quite as energy efficient as we'd like (ie, it isn't a passive house), but hopefully we can add some thermally broken triple glazed windows in a few years. We have a grid connected hybrid PV system and battery, we hope to upgrade our panels from 4.5kW to 10kW by the end of the year. We have a 17kW lead-acid gel battery, but only 4kW is routinely useable unless we lose the grid connection, this is the big problem with lead-acid batteries. Hopefully more panels will reduce the load on the battery.

We've tried to minimise power use in the house: it's all electric, 2x Daikin US7 for HVAC, a Sanden Heat Pump, all LED lighting, and a reasonably well sealed house, with R6 insulation floor and ceiling, R2.5 in the walls, along with good passive orientation and siting the house for cross flow cooling. Despite that, we are regularly using 20kWh a day (up to 30kWh when we charge the car). We have a reed bed sewerage system that treats grey and black water on-site, a 40,000L tank water supply, mainly for fire suppression to our rooftop sprinklers, automated to activate at 50 degrees, and we have a permanent spring for fresh water.

One of our main energy uses is a Tesla Model S. Our grid connection makes it difficult to charge directly from rooftop PV, AusNet, the world's worst power company to deal with, has made us connect the house to one circuit of 40A x2 two phase, and the charger on the other phase, so the charger doesn't see the renewable power.

Future projects:

sustainable garden, based on the reed bed wicking trenches.

extra PV capacity

triple glazed thermally broken windows

Cybertruck, if I can manage it without a divorce😀

[Marc]

Howdy Prof, and thanks for the introduction. I'm struggling to follow the circuit config you mentioned?

[Prof Tournesol]

We have a 2 phase supply to the house, each phase carries 40A. AusNet made us put the house, including rooftop PV and battery, on one phase and the EVSE on the other phase

[Marc]

I'm clearly showing my lack of understanding here on the electrical side, so please excuse the stupid questions.

So I'm single phase. Of three potential phases, our house has access to 'one'?

In your case, you have access to three phase, but for some reason (?) only access to two of those potential three phases - is that correct? Why not all three phases?

[Prof Tournesol]

No, we have two phases, not three. AusNet made us connect it so that the house runs of 40A single phase, the EVSE off the other. I'm not an electrician either, I don't know how it's done but that was their condition for connection. I never should have mentioned the charger to them.

[Marc]

I see. Learn something new every day! 🙂

[VectorONE]

Should have jumped on here earlier.

Buildings are assigned phases depending on appliance consumption specifications with respect to grid availability in the particular area.

Extreme end examples:

Remote farms usually have only one phase available ( if still on an old infrastructure area) If 3 phases are needed, a generator will have to be procured.

Some old homes that were built within an industrial area will have available access to all three phases should you wish to run a machine shed in the back yard.

[koputai]

In a lot of the older suburbs of Sydney, three phase power is normal.

Post-war a lot of Sydney houses installed three phase instant electric water heaters. The classis unit was the Simplex which pulled eighteen amps per phase.

 

Cheers,

Jason.