Solution to the above is to move everything onto the one phase.  Is there a reason that hasn't been done already?

That is not a solution if...

- you have equipment that needs 3 phase (tools, heatpumps, or faster charging EV)
- you have higher power requirements than can be met via a single phase (unlikely if you are building new and can get a single 100A feed, but not always available)
- you want to export more solar than your lines company allows per phase
- your property is already wired for multiple phases, which is usually something like 3x 40-60A.

Mine is the last one. House and workshop are already wired with 3x 50A phases (i think). With the amount of existing loads I have is not really practical to put them all on one 50A phase. But yes if that was possible then I could have had a cheaper solar setup that would have higher self-consumption.

In my mind the better, more future proof solution was to keep the 3 phase and have as large a solar array as possible. Also nicer for the power quality on the line. With EV's in the future I dont expect power requirements to go down....

It would just be nice if NZ metered this like the rest of the world rather than penalising those of us living the multi-phase lifestyle 😃

MadEngineer:

Solution to the above is to move everything onto the one phase.  Is there a reason that hasn't been done already?

Somehow I doubt that someone consuming 3x50A will be concerned about where their 3KW of solar generation will be going

MadEngineer:

Somehow I doubt that someone consuming 3x50A will be concerned about where their 3KW of solar generation will be going

MadEngineer:

 

Somehow I doubt that someone consuming 3x50A will be concerned about where their 3KW of solar generation will be going

 

Thats an odd thing to say given I have said thats exactly what I am concerned about...

Just because someone has 3x 50A capacity it doesnt mean they will be constantly pulling 150A. Once you add up the circuits in your house its easy to see potential big loads (30A cooktop, 25A oven, 15A per medium sized heatpump, 15A hot water, EV charger etc....) so having the additional capacity is a good thing. And given that you aren't pulling 150A all the time then having your loads as balanced as possible is currently very important.

But if NZ net metered over phases there would be no issue with getting full value from their solar and it would be a more attractive option for those on multi-phases

CrazyM:

 

MadEngineer:

 

Somehow I doubt that someone consuming 3x50A will be concerned about where their 3KW of solar generation will be going

 

 

 

 

Thats an odd thing to say given I have said thats exactly what I am concerned about...

 

You get the most benefit from consuming all your own power, rather than selling it. 

Since your loads are spread across 3 phases, that's going to be hard for you to do, net billing or not.

 

You get the most benefit from consuming all your own power, rather than selling it. 

 

Agreed

 

Since your loads are spread across 3 phases, that's going to be hard for you to do, net billing or not.

 

No, net billing would essentially aggregates your phases together and it measures as one power connection to your house, not 3. So it wouldn't matter on what phases power is being created or consumed. You could put single phase solar (or a single phase battery) on your system and the meter would allow it to offset power consumption on all the phases (moneywise, not electrons).

CrazyM:

 

No, net billing would essentially aggregates your phases together and it measures as one power connection to your house, not 3. So it wouldn't matter on what phases power is being created or consumed. You could put single phase solar (or a single phase battery) on your system and the meter would allow it to offset power consumption on all the phases (moneywise, not electrons).

 

D'oh. Yes, but is it likely there will be net billing in NZ ? That would mean the lines owners will be paying for the infrastructure but not getting paid for it from you or other solar users.

Even if you theoretically had an inverter that could dynamically power your phase that currently (ha) had the most load, that would probably run foul of the local distribution company who would probably want to know what generation was connected to what phase for balancing purposes.

elpenguino:

 

D'oh. Yes, but is it likely there will be net billing in NZ ? That would mean the lines owners will be paying for the infrastructure but not getting paid for it from you or other solar users.

 

Are you talking about net metering over time, or over phases? Because NZ is 1 of only 2 countries (i think) that meter this way across phases, and I'm not saying net metering over time is a fair solution.

Its probably not going to change in a hurry but the current situation certainly disincentivizes investment in renewable energy for people on multiple phases and care about their ROI. A battery is not a financially viably solution yet for most houses, but for 3 phase users with the current metering rules it likely never will.

With net metering over phases I would be paying exactly as much for infrastructure as a single phase user in regards to lines fees, network services, Electricity Authority levy, power costs etc...   Just with the ability to get the same ROI for solar as a single phase user. Its not a novel idea I've dreamt up, Australia is set up this was, as is the almost entirety of the rest of the world.

elpenguino:

 

Even if you theoretically had an inverter that could dynamically power your phase that currently (ha) had the most load, that would probably run foul of the local distribution company who would probably want to know what generation was connected to what phase for balancing purposes.

 

Well there are a couple of inverters out there that can do unbalanced output but they are expensive and are limited in their unbalancing capacity i.e a 10kW inverter cannot ever exceed 3.3kW per phase. There is also a NZ startup called Red Phase Technology that is supposedly making a dynamic load balancing box to do this, but the simpler solution would just be to flick a couple of 0's and 1's in the meter and measure home power usage like the rest of the world.

Highly unlikely that a local distribution company would care about residential solar production for balancing purposes as ~10kW is just too low to worry about, and thats only on a sunny day. Also if phase balancing was a big concern then they should be championing people with their loads and generation evenly distributed over 3 phases, rather than doing what MadEngineer suggested and piling all their loads onto a single phase leaving the others doing nothing (but also having to be available and allocated in case a load does get connected in the future)

I have 3-phase and are a high user (~100 kWh/day, two EVs) but haven't gone for solar because it doesn't make economical sense when I get power at a flat rate of 14c/kWh.

However, when looking at this it seemed that AS/NZS 4777.2 Clause 6.2.4 allowed for a voltage balancing mode/unbalanced load support in Inverters which means that they put greater output on the phases that have more demand. Thus avoiding instantaneously exporting on one phase when importing on another.

The Solax X3-Hybrid is one example that appears to support this (pg 65):

https://www.solaxpower.com/wp-content/uploads/2020/02/X3-Hybrid-User-Manual.pdf

In general I'm not in favour of net billing, would cause a distortion of the market with undesirable consequences. Retailers would make a loss on all exported units that they had to buy meaning that prices would increase for everyone to effectively subsidy solar. We'd then end up with an excess of generation during the middle of the day with less new generation that is useful in the evenings.

zenourn:

 

I have 3-phase and are a high user (~100 kWh/day, two EVs) but haven't gone for solar because it doesn't make economical sense when I get power at a flat rate of 14c/kWh.

 

However, when looking at this it seemed that AS/NZS 4777.2 Clause 6.2.4 allowed for a voltage balancing mode/unbalanced load support in Inverters which means that they put greater output on the phases that have more demand. Thus avoiding instantaneously exporting on one phase when importing on another.

 

The Solax X3-Hybrid is one example that appears to support this (pg 65):

 

https://www.solaxpower.com/wp-content/uploads/2020/02/X3-Hybrid-User-Manual.pdf

 

In general I'm not in favour of net billing, would cause a distortion of the market with undesirable consequences. Retailers would make a loss on all exported units that they had to buy meaning that prices would increase for everyone to effectively subsidy solar. We'd then end up with an excess of generation during the middle of the day with less new generation that is useful in the evenings.

 

Wow, how do you get a power rate like that?>

For other people in the same boat who might be investigating 3 phase inverters the Solax x3 does unbalanced output, so does the Goodwe ET.

As mentioned I'm not in favour of net metering over the course of the day for the reasons you point out. I want the instanteneous net metering over the phases at a single house. Like Australia has. So that I can be buying 8kW from the grid rather than buying 10kW and selling 2kW at the same moment.

I'm a bit puzzled about all this stressing and concern about people with three phase electricity supply at their home.

In the area with which I'm familiar (the Powerco reticulation area - I used to work for Powerco a l-o-n-g time ago), the vast majority of urban & suburban residential properties have a single-phase 63A supply.
3-phase in town was a 'special order' item and attracted a higher ongoing line charge as well as extra installation costs. There was a small proportion of 2-phase homes, usually with the stove on one phase and everything else on the other phase. AFAIK these were early 'all-electric' homes from the 1950s & 1960s: they may have had a smaller 'mains fuse', maybe 40A or 50A per phase?

I'm aware that Vector (former AEPB) charges the same in line charges for single- or 3-phase, but I think they're unusual in that respect.

So, what proportion of NZ urban residential electricity customers have a 3-phase supply?
1%? 5%? 10%? 20%? ???

CrazyM:

 

Wow, how do you get a power rate like that?>

 

For other people in the same boat who might be investigating 3 phase inverters the Solax x3 does unbalanced output, so does the Goodwe ET.

 

As mentioned I'm not in favour of net metering over the course of the day for the reasons you point out. I want the instanteneous net metering over the phases at a single house. Like Australia has. So that I can be buying 8kW from the grid rather than buying 10kW and selling 2kW at the same moment.

 

Here in North Canterbury the lines company changed to a larger fixed daily charge with a smaller variable charge of $0.02/kWh on the basis that most of their costs are fixed. When they made the change I saved over $1k per year!

I agree that it should be instantaneous net metering over the phases at a single house. Although I can definitely see the advantage of encouraging as much self consumption over phases as possible and minimising voltage differences: Being rural we are on a small 30 kVA transformer shared with another two other houses and when I do single-phase charging at 32A you can really see the voltage in that phase drop compared to the others.

PolicyGuy:

 

I'm a bit puzzled about all this stressing and concern about people with three phase electricity supply at their home.

 

In the area with which I'm familiar (the Powerco reticulation area - I used to work for Powerco a l-o-n-g time ago), the vast majority of urban & suburban residential properties have a single-phase 63A supply.
3-phase in town was a 'special order' item and attracted a higher ongoing line charge as well as extra installation costs. There was a small proportion of 2-phase homes, usually with the stove on one phase and everything else on the other phase. AFAIK these were early 'all-electric' homes from the 1950s & 1960s: they may have had a smaller 'mains fuse', maybe 40A or 50A per phase?

 

I'm aware that Vector (former AEPB) charges the same in line charges for single- or 3-phase, but I think they're unusual in that respect.

 

So, what proportion of NZ urban residential electricity customers have a 3-phase supply?
1%? 5%? 10%? 20%? ???

 

Id be interested to know the proportion too, but why limit it to urban? Not everyone lives in town.

I'm rural (lifestyle block), and 2 or 3 phase on rural properties is very common.  I also suspect that more and more builds will head this way as EV's become more mainstream. Single phase 63A is quite restrictive these days if you are purely electric and dont have wood fire or gas. Heck, I'm having to get a 30A breaker put in at the moment for just a normal 60cm induction cooktop!

I dont there there is much stressing or concern going on, just trying to highlight some issues with 3 phase solar that people should be aware of. The current metering system makes 3 phase solar very difficult from a ROI perspective, and it means a battery is even further out of the question.