Navitron Renewable Energy and Sustainability Forum

SOLAR PHOTOVOLTAIC => Solar Photovoltaic Systems => Topic started by: jonsamcor on April 16, 2019, 11:21:43 PM



Title: Why do I need 3 phase electricity to install P.V. ?
Post by: jonsamcor on April 16, 2019, 11:21:43 PM
I looked into PV a while ago ...but I need 3 phase electrical supply....

I have a 6kw turbine was the reason the suppliers told I needed 3P

Could someone in (relatively) simple terms give me a explanation why ? Or point me to a link....

The quote from the network or infrastructure element of the local energy supplier quoted £8k for bringing 3phase electricity to me ...

Curious, have a good site with great  air quality

Jonny


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: paul149 on April 16, 2019, 11:31:58 PM
3 PH not needed for PV install of less than 3.68 kWp.
Who said you needed 3PH for PV, Turbine is not PV!
100,000+ PV installs in Domestic properties that do not have 3PH!

Paul m.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: oliver90owner on April 17, 2019, 12:08:46 AM
You can’t just keep loading up on one phase.  How much PV were you thinking of installing?

With the potential of 6kW, and then the PV, going into the one phase I’m not particularly surprised they are insisting on a three phase connection.  I don’t know the actual rules - but not surprised.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 17, 2019, 01:50:45 AM
I looked into PV a while ago ...but I need 3 phase electrical supply....

I have a 6kw turbine was the reason the suppliers told I needed 3P

Could someone in (relatively) simple terms give me a explanation why ? Or point me to a link....

The quote from the network or infrastructure element of the local energy supplier quoted £8k for bringing 3phase electricity to me ...

Curious, have a good site with great  air quality

Jonny


What he was considering was the amount of peak electricity you could be exported to the grid if both your wind and PV were grid tried. This is a conversation to have with your local network provider as they are the ones who impose such limits.

One way around any restrictions will be to deploy a solution from SMA that varies the output of the inverters so that your total export never exceeds whatever you agree with the local provider. I know they have this for their PV inverters, but I do not know about their Wind inverters. So you may find that the best configuration (and most likely the cheapest) just dials back the PV export to zero if your exported wind generation is high.

While your peak export will be restricted you would still be able to use all the possible output for personal consumption as the SMA solution varies the inverter(s) output real-time.

So the resulting additional cost will come from installing a set of SMA products rather than just a cheap inverter, regardless it will be far cheaper than a 3 phase supply and I would guess 3 phase inverters.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: jonsamcor on April 17, 2019, 06:41:29 AM
Guys thank you for the reply’s.... I will contact Power N.I. To see what they say ....
Is battery storage for “surplus” viable ?
It was the installers who said I needed 3 p btw ...


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: kristen on April 17, 2019, 06:55:58 AM
My "Renewables Guy" is tempting me with loads more on-roof PV, limited export (as described above) to not exceed permitted export [but they may allow me more than the regular minimum] and any excess going into batteries.  I'm definitely up for that ...


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: pdf27 on April 17, 2019, 07:11:33 AM
For those who might not be familiar with 3-phase, there is a really good reason that you don't want the phases to be out of balance. At the power station, the generator looks something like this:
(http://www.jirvine.co.uk/Electrical_%20Principles/Tutorial_13_3_Phase_AC/Images/Star_02.gif)
If you get unbalanced 3-phase, then you start to get current flowing through the star point which really can't cope with very much of it. You also from memory start to have problems locally keeping the voltage on all three phases the same, which then leads to cascading problems which might ultimately give you a misshapen sine-wave for the current and voltage.

For domestic customers, what typically happens is that a 3-phase supply will go to a street, and 1/3 of the houses will be on each phase. This tends to balance quite well, provided the houses are broadly similar (if 1 phase are all on electric heating and the rest on gas, that would be a problem for instance). The system can cope with some out of balance, and this has been codified as the requirement that houses fitted with PV can't export more than 13A to the grid at any time when on a single phase connection. It's very one-size-fits-all, but means they don't have to study every individual grid to see if it can take more.
If your house has a 3-phase supply, then you can split the export evenly over all 3 phases. The unbalanced load restriction goes away, and you're left with how much the grid can accept as export before the voltage gets too high - typically a much bigger number.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 17, 2019, 09:23:34 AM
Guys thank you for the reply’s.... I will contact Power N.I. To see what they say ....
Is battery storage for “surplus” viable ?
It was the installers who said I needed 3 p btw ...

Unless the installer knows the SMA product range very well they are unlikely to know that this is a possible configuration. The following video shows an SMA PV inverter being linked to an SMA Energy Meter.

      https: //www.youtube.com/watch?v=cJ108xc4TdQ

Battery storage is currently one big question mark. The issue is that the equipment cost is still falling year on year and at a rate that means for most people it is cheaper to just sit back unless they have a strong need. Also a lot will depend on if you think you will end up with an EV in the next few years. An EV purchase in 3-4 years from now will most likely allow the EV to power the home, so removing the need for most people to install a dedicated battery solution, but this is currently a large unknown as a few car manufacturers have talked about such systems, but none seem to have published firm plans.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: dan_b on April 17, 2019, 10:45:28 AM
Domestic V2G is probably still a way off as the charging/discharging units are big and expensive at the moment, and as you say, not that many cars out there are actually supporting V2G beyond the Leaf and its sibling the NV-200 van (it's built into the ChaDeMo standard), and, strangely enough considering the battery is so tiny, the Mitsubishi Outlander PHEV (in Japan).

Having said that, Ovo Energy is running a trial at the moment for V2G if you have a Nissan Leaf, https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger
And Robert Llewellyn is has a video coming up soon about domestic V2G on Fully Charged

(as an aside, Teslas have the capability for V2G but it's not enabled and I think the reason for this is pretty simple - free supercharging.  Tesla doesn't want owners going and sucking up large amounts of their freely-supplied supercharger electrons for the owners to then drive home, plug into V2G and then sell that electricity back to the grid for a profit!)


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 17, 2019, 11:10:27 AM
Domestic V2G is probably still a way off as the charging/discharging units are big and expensive at the moment, and as you say, not that many cars out there are actually supporting V2G beyond the Leaf and its sibling the NV-200 van (it's built into the ChaDeMo standard), and, strangely enough considering the battery is so tiny, the Mitsubishi Outlander PHEV (in Japan).

One of the things that has to be fixed (again) is the standards. ChaDeMo has had manufactures design a few solutions, but CCS is now the direction across the EU. CCS has both V2H and V2G on its roadmap, but also has the following caveat "Many requirements still missing".

The one good thing about CCS is the V2H and V2G split as V2H is defined as 'behind the meter' which may simplify the design and standards work when compared to a full high current V2G solution.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: kristen on April 17, 2019, 11:31:35 AM
I know its been kicked about before, but I struggle to get my head around V2G.

I come home and plug in, Car won't actually charge until schedule (during E7), but I have enough mileage for running around if "something unexpected comes up".

But if I discharged into house, during the evening, then I would not have any slack, until E7 charging is done ... and charging (7KW) adds 22 miles each hour ... I can't see the domestic supply infrastructure being upgraded, so presumably 7kW is going to remain the max for the foreseable?  It will be worse when we have 2x EVs to charge each night ... they will need to be done sequentially (or load balanced) so 7 hours E7 will be 77 miles per vehicle. Surely enough for most people's average commute, but not great for "outlier days". My car is not going to be parked at home, weekdays, to store my excess PV .. but maybe I will charge at work (to soak up the excess PV the nation will have, by then).

So I really struggle with whether I will be happy to discharge my EV into house in the evening ...

of course if batteries become cheap, adn light, and my car has 200kWh battery then "OKAY" :) but if battery is cheap then I might well have 100kWH car and 100kWH static battery in the house instead ... and enough PV to be self sufficient at home.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: dan_b on April 17, 2019, 11:36:32 AM
From what I understand, the concept to enable V2G at home is that they only really take a couple of kWh from the battery at peak times, and for the chargers to be smart enough to know what your regular charging patterns are for commuting etc so that they never leave you with so little charge you can't use the vehicle at all, and indeed would re-charge sufficiently before your planned use.  Of course that also gets easier the more V2G chargers are in an area, as then more EV batteries can be used, therefore discharging less from each battery.



Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: biff on April 17, 2019, 11:42:37 AM
Ir is nice to see the forum being used properly and good debate taking place with none of the hair pulling and eye gouging  you get on other forums.
     Excellent!
             Biff


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: kristen on April 17, 2019, 12:01:17 PM
... for the chargers to be smart enough to know what your regular charging patterns are for commuting etc ...

My range-anxiety relates to unexpected use. If the charger has ESP that would be great (like the Lifts in Hitchhikers Guide to the Galaxy that "arrive on the floor you are on before-you-know-you-need-one" :) )

It also relates to the slow refuel speed. I suppose if I took 7kWh out, for evening cooking, and then charged at 7kW I'm only waiting an hour ... but I don't suppose they will want to give me that 7kW until after midnight? unless it is blowing a hoolie in the North Sea ...

A Rapid Charger nearby (likely in the future) wouldn't be a huge help. My likely "emergency midnight journey" is likely to be rural - to a relative etc. and the only petrol stations we have around here are in town - only 10 minutes drive, but in the wrong direction.  Currently if my ICE tank was low I'd just fill up on the way home, so would never have the "unexpected use need, but empty tank" scenario ... squaring this "lifestyle change" circle seems the problem for me.

I don't see EV efficiency decreasing dramatically below 300 wH/mile, nor my home EV charger increasing above 7KW - so 23MPH

I'm definitely cool with the idea what V2G means that power company triggers that dischange, instead of spinning up a Peaker-Plant just because the Coronation Street adverts have come on :)

Maybe the reality is that my evening cooking / consumption is relatively tiny (compared to the battery size of an EV in a few years time), What's that likely to a be?


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 17, 2019, 01:08:43 PM
I know its been kicked about before, but I struggle to get my head around V2G.

I come home and plug in, Car won't actually charge until schedule (during E7), but I have enough mileage for running around if "something unexpected comes up".

But if I discharged into house, during the evening, then I would not have any slack, until E7 charging is done ... and charging (7KW) adds 22 miles each hour ... I can't see the domestic supply infrastructure being upgraded, so presumably 7kW is going to remain the max for the foreseable?  It will be worse when we have 2x EVs to charge each night ... they will need to be done sequentially (or load balanced) so 7 hours E7 will be 77 miles per vehicle. Surely enough for most people's average commute, but not great for "outlier days". My car is not going to be parked at home, weekdays, to store my excess PV .. but maybe I will charge at work (to soak up the excess PV the nation will have, by then).

So I really struggle with whether I will be happy to discharge my EV into house in the evening ...

of course if batteries become cheap, adn light, and my car has 200kWh battery then "OKAY" :) but if battery is cheap then I might well have 100kWH car and 100kWH static battery in the house instead ... and enough PV to be self sufficient at home.

This is why there seems to be a distinction between V2H, where during the evening the car may provide a few KW of energy to the home, much in the same way that a 5-10KWh battery installation may. While V2G is a grander vision, that would relate to the National Grid being able to call upon all the connected cars to meet the needs of the nation. Personally, I can get my head around V2H (my car, my usage), but I would like to see a large scale V2G up and running before I consider it.

As you have noted cars used for any distance of daily commute are not going to be the best choice for such systems, but a lot of people have lighter usage of their cars. It will be these people who get the chance to use V2H and V2G as their cars will be at home more often to recharge whenever the rate for electricity is right.

Again from a personal point of view, I am expecting that rather than deploying a home battery in a few years time, I will instead spend the money on a better spec'ed and intergrated EV. In today's market that would allow me to choose a 64KWh Kona, rather than a 40KWh version - so providing lots of flexablity.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: Countrypaul on April 17, 2019, 03:38:49 PM
Is there a reason the home chargers are limited to 7KW, as often home have a 100A supply so the home could probably cope with 20KW charging?
If you are going to have 2 EVs would both need to be kept charged for "emergency use" or would one be adequate - could make a large difference to how things are configured and whether V2G would be useful to you?


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: dan_b on April 17, 2019, 04:34:57 PM
7kW is 30Amps on one phase and the car could be drawing that amount of power for 6-8 hours, which does put quite a load on domestic 240v wiring, even if the main incomer is 100A.  20kW on a single phase (83Amps) is a lot closer to the main incomer limit and leaves nothing in reserve for the rest of the house or safety for the wiring so would never be permitted, especially along with the discussions about how the DNO has to balance the loads across the three phases on the low voltage network - if you had one house sucking in a radically disproportionately high amount of current for long periods on one phase, things get a bit sticky.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: Countrypaul on April 17, 2019, 06:50:46 PM
Any house that relies on storage heaters is likey to draw a high current for a prolonged period overnight. My parents house use to use 18KW overnight and during the afternoon in winter as it was entirely storage heaters (plus immersion) - not significantly different to what I was asking about regarding EV charging.

I thought the 100A mains fuse was there to protect the incoming main from overloading so already has a safety marging built in.

How big a supply is the main runing down the street normally?


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 17, 2019, 07:27:57 PM
Any house that relies on storage heaters is likey to draw a high current for a prolonged period overnight. My parents house use to use 18KW overnight and during the afternoon in winter as it was entirely storage heaters (plus immersion) - not significantly different to what I was asking about regarding EV charging.

I thought the 100A mains fuse was there to protect the incoming main from overloading so already has a safety marging built in.

How big a supply is the main runing down the street normally?

The limit is more about what has so far been needed by end users than any rules and regs. With the Leaf being the largest selling EV at 24 and then 40 KWh, there has not been much demand to develop larger home chargers.

There is nothing electrically to stop larger chargers to be installed in homes as long as the main fuse can cope - so I would guess a 14KW charger would be the next step. The real control will come from UK legislation that talks about 'Smart charge points'.

        http://www.legislation.gov.uk/ukpga/2018/18/pdfs/ukpgaen_20180018_en.pdf

These Explanatory Notes relate to theAutomated and Electric Vehicles Act 2018 (c. 18) which received Royal Assent on 19 July 2018/10/10

Quote
Section 15: Smart charge points

42 This Section provides the Secretary of State with the power to introduce regulations prohibiting the sale or installation of charge points in the United Kingdom, unless they meet certain requirements, which will be prescribed in regulations. This includes charge points that may be given away for free or on hire (for example, as part of the sale of a vehicle).

43 Subsection (2) provides that the prescribed requirements may include (but are not limited to) requirements that relate to technical specifications for a charge point, such as “smart” functionality,and provision about the ability of the charge point to: send and receive electronic communications to and from a third party; react to the information sent or received from the third party and adjust the charge point’s charging (or discharging) rate; monitor and record the charge point’s own energy usage; comply with sufficient security requirements to ensure that it is resilient to a cyber-attack or other types of attack; achieve energy efficiency standards,and to be capable of being accessed remotely.

Section 16: Enforcement

44 This Section confers power on the Secretary of State to make regulations so as to enforce compliance with the requirements in this Part. These regulations may set out a civil penalty regime and the process for determining whether there has been a failure to comply with any of the requirements. It is likely the Secretary of State will identify and nominate an existing body to undertake enforcement of any regulations. For example, if it is found by the enforcement authority that there has been a failure to comply, the enforcement authority will be able to issue a financial penalty that is payable into the consolidated fund.

45 Subsection (3) provides that regulations may make provision for conferring powers which may be required in determining whether a breach of the requirements has taken place. These include a power to enter any land, to inspect documents or things, and to remove anything for testing or inspection.

So you can have any size charger you like as long as the government can control it's operation.



Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: oliver90owner on April 17, 2019, 08:58:16 PM
In a similar vein to Countrypaul, nothing stopping anyone having two EV chargers.  Likely the ‘granny cable’ would suffice as a second one for most occasions.....

Too much introverted thinking?  There are many out there with differing personal situations, regarding electrical usage.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: kristen on April 18, 2019, 06:58:32 AM
I wonder if a 14kW charger would make a tangible difference?  7kW is 23-ish miles charge in an hour.  if I am in a hurry for juice (come home empty, then suddenly need to go somewhere) I don't think waiting an hour for 46 miles is going to help - assuming I have enough range I'll drive a few miles to a Rapid charger - currently 300 MPH charge, shortly 1,000 MPH to become available (so 80 miles in 5 minutes).

7kW shared between two (or more) cars overnight is not great - 7 hours (e.g. E7) @ 7kW = 160 miles, or 80 miles each car. More than most people's commute ... but not everyone.  That gets worse when considering the 4-hour off peak that some EV Charge Leccy rates are offering.

But I suppose 2 x 7kW chargers running concurrently, on a 100 AMP fuse and in the middle of the night, would be doable.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: brackwell on April 18, 2019, 07:35:36 AM
Hold on guys. If this is all done under legal regs then one as to consider all the potential electrical drawings in some way added together. The regulations apportion different load factors to different electrical items  (sorry i have seen the list but cannot find it now) and this is based on the fact that all items will not be on at the same time. eg EV may be 100% but a shower may be only 20% because as likely as not it will not be on as the same time as the cooker or fridge (although it could be).  The main fuse into the house can be 60 or 80 or 100amps (written on outside of box). AS i understand it the main fuse will take nearly twice the rated for short periods, multiple minutes.

This as all come to light on EV forums where some people have been refused the fitting of a 7kw EV charger because this would bring the total above the fuse. So in short for many 7kw is close to the max legal fitting by a certified electrician.
If you find you have a 60/80 amp fuse it can be uprated to 100amps in many cases but it costs.

Sorry but i am not an electrician.

Ken


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: kristen on April 18, 2019, 08:37:21 AM
This as all come to light on EV forums where some people have been refused the fitting of a 7kw EV charger because this would bring the total above the fuse. So in short for many 7kw is close to the max legal fitting by a certified electrician.

I have read of people having a "device" fitted to car charger which turns it off when other usage draws too much e.g. all the folk in the house are using their power showers. Might that be a solution? Given that the car needs to charge for "hours" a break for 15 minutes now and again won't matter, and with smart meters The Grid might do similar

Quote
Sorry but i am not an electrician.

Nor me ...


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: Ted on April 18, 2019, 08:51:11 AM
Hold on guys. If this is all done under legal regs then one as to consider all the potential electrical drawings in some way added together. The regulations apportion different load factors to different electrical items  (sorry i have seen the list but cannot find it now) and this is based on the fact that all items will not be on at the same time. eg EV may be 100% but a shower may be only 20% because as likely as not it will not be on as the same time as the cooker or fridge (although it could be).  The main fuse into the house can be 60 or 80 or 100amps (written on outside of box). AS i understand it the main fuse will take nearly twice the rated for short periods, multiple minutes.

This as all come to light on EV forums where some people have been refused the fitting of a 7kw EV charger because this would bring the total above the fuse. So in short for many 7kw is close to the max legal fitting by a certified electrician.
If you find you have a 60/80 amp fuse it can be uprated to 100amps in many cases but it costs.

Sorry but i am not an electrician.

Ken

Ken, what you are talking about is called 'diversity' and the data that electrcians can use to calculate it is set out in a book called The On-Site Guide.

This is a brief (but possibly outdated) overview - www.napitonline.com/downloads/CP%204%2007%20P%2010-11%2016th%20Diversity.pdf



Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: oliver90owner on April 18, 2019, 08:51:41 AM

Quote
Sorry but i am not an electrician.

Nor me ...
[/quote]

You don’t need to be!  If your fuse is 80Amps just keep below 19kW total power usage from the grid!

Of course using a 7kW charger could exceed the residence current limit - if used at the same time as electric storage heating, or similar circumstances, and any proper electrician would advise on that.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: brackwell on April 18, 2019, 09:04:26 AM
Thanks Ted. Can you lay your hands on the %s used ?

RAB  Just adding all the max possibles in a house would make nearly every house illegal!


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 18, 2019, 12:43:34 PM
Hold on guys. If this is all done under legal regs then one as to consider all the potential electrical drawings in some way added together. The regulations apportion different load factors to different electrical items  (sorry i have seen the list but cannot find it now) and this is based on the fact that all items will not be on at the same time. eg EV may be 100% but a shower may be only 20% because as likely as not it will not be on as the same time as the cooker or fridge (although it could be).  The main fuse into the house can be 60 or 80 or 100amps (written on outside of box). AS i understand it the main fuse will take nearly twice the rated for short periods, multiple minutes.

This as all come to light on EV forums where some people have been refused the fitting of a 7kw EV charger because this would bring the total above the fuse. So in short for many 7kw is close to the max legal fitting by a certified electrician.
If you find you have a 60/80 amp fuse it can be uprated to 100amps in many cases but it costs.

Sorry but i am not an electrician.

Ken

Very true, if a home is built around night storage heaters with a fuse designed to cope with their load the adding of an EV charger that is to use E7 energy should cause a good electrician to stop. This can be resolved with the Zappi 7kW charger as not only does it support charging based on export levels, but also charging based on import levels.

The future issue is that electricians are not required to consider the power requirements for a neighbourhood (It's just not their job) so the installing of many chargers in many homes is currently not a consideration. Current protection comes from whatever low voltage rules the device manufacturers have implemented, but there are no formal rules governing EV chargers that I have found - The Zappi list of compliance documents cover a lot of things but not how to operate as the supply voltage drops. As the Zappi is one of the few variable rate chargers it is one of the few that could reduce the charge rate as the supply voltage drops, most others would have to just shut down.

These issues are the reason for the law I detailed above - the ability of a central body being able to control the energy draw of all EV chargers in the future. This logically means that in the future all home chargers are going to have to be variable rate units (like the Zappi) or owners of fixed rate high current units may find that they can not charge the cars overnight.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: kristen on April 18, 2019, 01:04:46 PM
The Zappi list of compliance documents cover a lot of things but not how to operate as the supply voltage drops. As the Zappi is one of the few variable rate chargers it is one of the few that could reduce the charge rate as the supply voltage drops, most others would have to just shut down.

Sorry, I don't know the details, but Tesla can reduce the current drawn. I can change it from the dashboard (e.g. dial it down if I charge at friend's house and find the 13 AMP plug is getting hot), and I think the car does it too - maybe if voltage drops? pretty sure that the AMP setting is GPS-aware too (I've had it wrong at home, presumably because I changed it at some point, but it was still "MAX" when charging at work).

At this "from memory" though, so could be off beam.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: RIT on April 18, 2019, 03:29:06 PM
The Zappi list of compliance documents cover a lot of things but not how to operate as the supply voltage drops. As the Zappi is one of the few variable rate chargers it is one of the few that could reduce the charge rate as the supply voltage drops, most others would have to just shut down.

Sorry, I don't know the details, but Tesla can reduce the current drawn. I can change it from the dashboard (e.g. dial it down if I charge at friend's house and find the 13 AMP plug is getting hot), and I think the car does it too - maybe if voltage drops? pretty sure that the AMP setting is GPS-aware too (I've had it wrong at home, presumably because I changed it at some point, but it was still "MAX" when charging at work).

At this "from memory" though, so could be off beam.

Just about all the chargers built into cars can vary their charge rate as they have to be able to lower the rate at which they charge as the battery gets to 80% and above, they should also be able to vary the rate based on the battery temperature (as seen with the 40 kWh Leaf issues). The issue is that the car side charger is doing this in isolation and based around the car's own requirements or some general user settings.

The home and business charging stations are where the controls for the current draw against things like fuse ratings and grid demand management are being placed or will be placed in the future as these control the maximum current that any connected car's built-in charger can then draw.

As I understand it the Tesla has a lot more functionality in its car charger for external connections as its built-in charger and Universal Mobile Connector (UMC) cable supports connections between 2.3kW(UK 13A 240v) and 11kW (5 Pin 3 Phase) using (I think) a Type 2 interface, with Chademo and Supercharger being other possible connections. Other EVs don't have quite the same level of flexibility. For example, the new Kona only has built-in support Type 2 support up to 7kW and CCS, but even this can be considered a step up as the 24/40kW Leafs are Type 1 (up to 6.6kW) and Chademo.


Looking into the above I do now have an explanation to why we only see 7kW home charging stations at the moment - They provide an AC source that depends on the car's built-in charger. As few manufacturers (apart from Tesla) had deployed larger chargers there is no demand for larger AC stations. The next step would be a Chademo/CCS solution, but these are costly and are all designed for business environments where a 3 Phase supply would be the norm.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: Ted on April 18, 2019, 05:28:35 PM
Thanks Ted. Can you lay your hands on the %s used ?

RAB  Just adding all the max possibles in a house would make nearly every house illegal!

For domestic dwellings the figures for calculating the current demand for an installation from my old (2008) OSG are in Appendix 1 Table 1B:

Lighting66%
Heating and power100% upto 10A then 50% in excess of that
Cooking100% up to 10A plus 30%, plus 5A for a cooker socket
Instantaneous water-heaters100%
Thermostatic water-heatersNo diversity
Floor warmingNo diversity
Thermal store space heatingNo diversity
Standard final circuits (App 8) 100% of largest circuit plus 40% of all others
Sockets other than those covered above *100% of largest demand point plus 40% of all other points

* and all other stationary equipment not otherwise included

App 8 circuit sizes are determined by their overcurrent protective device.

Consumer units need to be rated without any allowance for diversity.

System designers are allowed to use other figures where they can be justified.


Title: Re: Why do I need 3 phase electricity to install P.V. ?
Post by: DonL on April 22, 2019, 09:40:04 AM
The Zappi charger offers the facility to monitor total load using a CT on the supply and decreases the charge rate to the car if the supply reaches a limit you can set.  So if your car is on charge and the total current reaches the preset value it will cut back on the charge rate to the car to respect the limit. When total supply current drops as other high load devices turn off the charge rate to the car ramps back up.
I have this working, in a slightly modified form to prevent possible overloading on the supply to outbuildings.
It works and I have watched it turn down and balance the current when I turn on a fan heater.
I'm unsure how this is considered in terms of diversity and the regs but it certainly works in practise.
Don