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Author Topic: Why do I need 3 phase electricity to install P.V. ?  (Read 1075 times)
jonsamcor
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« 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
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Rural Co. Down, Proven 6kw Turbine, GSHP, Thermomax Tubes....and Total lack of technical or useful knowledge
paul149
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« Reply #1 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.
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3.5 kWp (14 x Sanyo H250E01 + SB3000TL) 225' (SW) at 35' Pitch Lat 51.30' (Bristol) Installed cost £2.63/Wp (Nov 2011) now with solarimmersion and 250L unvented dhw (Almost Zero gas input for DHW from Apr to mid Sep)
oliver90owner
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« Reply #2 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.
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RIT
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« Reply #3 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.
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Why bother? - well, there is no planet B
jonsamcor
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« Reply #4 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 ...
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kristen
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« Reply #5 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 ...
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pdf27
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« Reply #6 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:

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.
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RIT
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« Reply #7 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.
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2.4kW PV system, output can be seen at  - https://pvoutput.org/list.jsp?userid=49083

Why bother? - well, there is no planet B
dan_b
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« Reply #8 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!)
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RIT
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« Reply #9 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.
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2.4kW PV system, output can be seen at  - https://pvoutput.org/list.jsp?userid=49083

Why bother? - well, there is no planet B
kristen
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« Reply #10 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" Smiley 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.
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dan_b
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« Reply #11 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.

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3.06kWp SolarEdge system with a split array:
2.18kWp 10x South facing, plus 4x West facing 880W

Mk1 ImmerSUN DHW diverter
4kW PowerVault Battery
biff
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« Reply #12 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
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kristen
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« Reply #13 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" Smiley )

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 Smiley

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?
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RIT
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« Reply #14 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" Smiley 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.
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2.4kW PV system, output can be seen at  - https://pvoutput.org/list.jsp?userid=49083

Why bother? - well, there is no planet B
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