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Wkipedia knows it: Three-phase - Wikipedia[^]
Here in Germany power is always supplied as 3-phase for building connections. But private households usually do not have equipment that requires it. The only common devices that have 3-phase connections are cookers. But they just split it into three 240 V lines internally (e.g. one for the stove and the others for two plates each) and can be usually also connected to one or more 240 V lines.
Similar is done in the distribution boxes: Splitting into three 240 V lines for supporting the different connections.
There is also no "3-phase battery solution". There are DC batteries loaded by the panels and a switch supply generating the required AC. You might ask an electrician if it is really necessary to use a 3-phase switch or if the output of a 240 V switch can be attached to some or one of the 240 V lines from the distribution box (assuming that the solar power is not able to power the whole house).
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We pump the same amount into the grid during the day as we use after the sun stops, paying 50c kwh getting 6c kwh. If I could use that 50% I could almost eliminate the power bill.
Never underestimate the power of human stupidity
RAH
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You could buy a threephase UPS and modify it.
But they're f***ing expensive.
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Sounds good. Then you already have a switch supply and just need some batteries inbetween (and calculate the time until it gets a good return).
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I think that it is standard in most European countries with the exception of UK.
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Jochen Arndt wrote: But private households usually do not have equipment that requires it. The only common devices that have 3-phase connections are cookers.
Anything that contains large electrical motors may be wired for 3-phase. For domestic use, that may go for centralized air condition systems, as well as for heat pump systems for ground collectors. (Yes, the two are essentially the same thing in different wrapping!)
If you go green and get yourself an electrical car, fast chargers usually require a 3phase power supply.
Traditional hot water heaters has here in Norway been tanks of typically 2-300 liters of water preheated to 80-95 C, with a heat loss of typically 100W, or 1000 kWh per year. If house is poorly insulated, the loss may useful as house heating, maybe 6-9 months of the year here in Norway. With modern, well insulated houses, it is a waste, and some people replace the tank with an electrical on-the-fly heater (like gas heaters common in some other countries). These typically draws 25-30 kW while the water is running. At those levels, we use 3 phase power as well.
In "the old days", say, 30+ years ago, 3-phase was not common in households, although it might be available in the cable in the street. I didn't have 3phase to my house, but having it installed 25-30 years ago was straightforward. Today I need it for the heat pump (ground heat) and the sauna heater. Since I am on an IT grid, I can't get a 3phase car charger (unless I buy an expensive, huge transformer for IT-to-TN network), but on the other hand: I just bought myself a new car that is NOT electric.
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Quote: Now I'm looking for and efficient 3 phase battery solution.
In case you are NOT joking... (The above is the sort of joke EE guys might crack!):
There is no such thing as "phases" in battery power. With 3-phase AC, (in the most common layout, you have 4 wires coming into your house. One is neutral, the 3 others carry a voltage varying along a 50 Hz (Europe) or 60 Hz (US) sine curve, relative to the neutral line. The 3 are "out of step" with each other, by one third of the entire 50/60 Hz sine curve, i.e. the voltage on the second wire reaches it peak 1/150 (US: 1/180) sec after the peak of the first wire, the third wire peak comes 2/150 (US: 2/180) sec after the first one - and after 3/150 (US: 3/180) sec, the first wire is at its next peak.
Battery voltage is flat, it doesn't come in sine curves. It has no peak recurring every 1/50 (US: 1/60) second. If you need that, you may use the battery power to drive a DC motor that pulls a generator (i.e. a dynamo), which may provide either a single sine-curve voltage, or three that is out of step, like your old 3-phase power supply. Today, the motor and dynamo is frequently replaced with electronics that do the same thing without moving parts, and with lower losses; it is often termed an "inverter".
Practically all your electric appliances do NOT use 3phase power: They hook up to the neutral wire and one of the 3, ignoring the remaining two. So they see only a single sine curve voltage, a single phase. Your power company is very happy if you hook up your dishwasher between wire 1 and neutral, your washing machine between wire 2 and neutral, and your electric heater between line 3 and neutral, in particular if you run them at the same time. If you put them all on the same wire, leaving the other two un-utilized, it might contribute to imbalance of the power supply system. (It is less of a problem if your 1000-houshold neighbourhood hooks up to the same supply transformer, but it is nevertheless a good practice. The decision which wire to use is done when your fuse box is installed: The circuit feeding your dishwasher hooks up to power wire 1, the circuit to you laundry room hooks to power wire 2 etc. So you don't have to worry about this in your daily life, but if you build a new house, the electrician doing the hookup should be informed about your major power surges, so that those circuits are distributed over the 3 power lines.
There ARE appliances that hook up to all three power wires (plus neutral), usually those containing large electrical motors driving e.g. huge compressors for AC or heat pumps, or heavy machine tools like big saws etc. These either have a fixed power connection, or a plug that looks very different from your ordinary plug. Most homes do not have them; a domestic-model cooler drawing less than 2000W usually uses an ordinary plug for 1-phase current.
So, essentially, you don't have to worry about 3-phase. You get yourself a 1-phase inverter (of sufficient power) and plug all your ordinary 1-phase equipment into that.
BUT... Be realistic about the battery capacities! An ordinary car battery has a capacity of maybe 60 Ah (it varies, but 60 Ah is typical). That is at 12V. So the energy is 12V*60Ah = 720Wh, or in more familiar terms, 0.72 kWh. If you plug in a 2 kW heating fan (i.e. one consuming 2 kWh per hour), the battery is completely drained in about 20 minutes. Even a modern, energy-efficient dishwasher og washing machine uses around 1 kWh per run, so a single 60 Ah battery is significantly below the capacity required by a single run. You may need to fill your entire basement with batteries...
Modern Li-Ion batteries are more compact and have higher capacity. But be realistic: Check your power meter, see how much electricity your household uses per day on the average. Expect the peak days to be at least twice the average. For dimensioning, in middle Europe (i.e. not very cold climate), it is common to estimate 9-10,000 kWh/year, i.e. 25-30 kWh a day. To supply a single day of power needs from batteries (assuming no refillng available), would require 40 standard 12V 60Ah batteries.
If you can guarantee that your solar panels every day throughout the entire year will receive enough sunshine to recharge your batteries with (at least) 25-30 kWh/day. That might be realistic in California, but not here in Norway, especially not at winter time.
My advise: Restrict solar power and batteries to low-power use, such as LED lights, burglar alarm, network router, tabletop radio (but NOT a huge stereo system that can shake the entire house), charging your phones, pads and laptops (but not your full-size tower PC with a 30 in screen).
For heating (including hot water), you will be much better off using thermal collectors - they pick up 4-5 times as much energy from the sun. Depending on you local conditions, a wood stove may be nice (and I love the radiated heat, the smell and the sound). For cooking, gas is standard in many cultures. Leave vacuum cleaners, dishwashers, laundry machines and other high-effect equipment to the old power line hookup.
In case of a power fallout you still have light, heating, communication and at least some entertainment. If there is a risk of longer fallouts, you might invest in a gasoline/diesel powered generator for emergency cases - but models big enough to feed, say, your laundry machine (maybe it draws 2000W when heating the water) are large, expensive and noisy. You don't want to use them except in emergency situations.
A final note about 3-phase, which you probably can ignore: There is an alternate wiring scheme, with no 4th neutral wire: You hook up ordinary 1-phase power consumers between wire 1 and 2, between 2 and 3 or between 3 and 1. This is referred to as "delta" or "IT" wiring (as opposed to the far more common "star" or "TN" wiring I assumed above). In Norway, IT wiring is still common, roughly 80% of the installations, but TN wiring is used in new setups. Few other countries use IT wiring to any degree. (It is used internally in some hospitals, due to certain safety issues.)
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It is tough when you have to scroll up to vote 
You have expanded my limited knowledge rather dramatically, thank you.
The guy who built the house over engineered everything, not just the power. As he was an inventor (and now lives off patents) I can understand why.
It will be worth getting an electrician to investigate the wiring and see if I can identify the circuit most important to the house. The goal is to reduce the power bill to the minimum rather than survive an emergency.
I have been to Norway in the winter and I live in Cairns which is about as different as you can get. So sunshine volume is not a problem. An 8kw solar drives the house including a substantial A/C and pool pump during the day with 50% left over, I want that 50%.
Never underestimate the power of human stupidity
RAH
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Mycroft Holmes wrote: Following that logic would 240VAC be better than 120VAC, Oz runs on 240 and I have always wondered why, other than we probably followed the UK standards.
No idea on your specific history, but 100+ years ago when electrification was beginning 120 vs 240 was a cointoss on costs. 240 needed thinner copper wires than 120; but needed double the insulation thickness. 240 wins hands down on wiring cost today because plastic is cheap and copper expensive; but at the time the cost of the thicker insulation completely negated the savings on thinner wire.
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, weighing all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius
Training a telescope on one’s own belly button will only reveal lint. You like that? You go right on staring at it. I prefer looking at galaxies.
-- Sarah Hoyt
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Quote: Now I'm looking for and [sic] efficient 3 phase battery solution.
Do you mean 3-phase supplied by an inverter? That's done easily enough. But by definition you cannot have 3-phase d.c. 
As Sasha says, the higher the voltage, the lower the line losses. Look at power tools and electric vehicles for examples - all these are 'better' (more power available, lower losses) the higher the voltage employed.
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I am putting together such a system at the moment but only the outdoor lighting will be off pure DC - the rest will be through DC/AC inverter.
If you are doing a separate circuit this is reasonably easy. If you want to feed the solar into your existing mains power you need a grid tie inverter (so your phase matches the AC phase of the power company) and probably a professional electrician at that stage.
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I am currently setting up my own 12VDC net, but as you might infer from my other posts here: Only for low-effect use: Light, communication, alarm.
I am not at all worried about the power bill, that's not why, but the bill from the electrician. Here in Norway you can't legally do much more than replacing burned-out light bulbs without calling an electrician. I want to handle things myself, setting up alternate switches, adding lights etc. And I want to keep communication and light and alarms operative even during power outages.
Do not ignore cable length concerns! I put a battery bank in my loft, next to the central chimney, with a start of cables straigth to above the ceiling light, or wall lamp, charging socket etc. in the floor below. It cost a few extra meters of cabling, but the voltage loss is reduced both due to shorter distance and lower current - the current is spread over a number of wires. Also, that allows me to use smaller, lower-amp, fuses for each of the connections, giving better protection. And if I blow the fuse of one lamp, there are still light in the others.
I plan another battery bank in the basement - it saves 5-6 meters of cabling (two floor heights), both for light, small fans and networking equipment. Getting straight to the point of light might take some drilling through concrete walls.
The batteries will be charged from four panels that might in theory deliver a peak effect of about 900 W. That is highly theoretical! Two panels will be roof mounted, at 23 degrees angle from the horizontal plane, direction south-west (ideal a few hours after noon in April and August). Two panels will be wall mounted, vertically, directly towards SW and SE, respectively. I will have to see how much power I get in practice: If needed, I can easily mount two more on the roof.
I hope to keep the batteries charged by sun alone from late February or March through September. From early October to mid February, the aun is so weak that it won't give much, and from December (or earlier) the roof panels may be covered by snow. So during the winter months, the necessary power to keep the batteries fully charged will be taken from the power grid. (I want to keep them fully charged especially during winter - that is the season for power outages!)
For heating I use thermal collectors and a heat pump for ground heat. The thermal collectors keep the yield at a usable level far longer into late fall, and earlier in spring, than the photocells, and are more than four times as efficient. I do NOT plan on using solar panels for heating. (Except that to handle power outages, I will install 12VDC circulation pumps in the solar heating system; these have far lower effect than the main circulation pumps, but will give some heat to the floors.
Looking up power meter readings from a few years back, when the house was exlusively electrically heated, LED lights hadn't yet arrived on the market, we were three persons taking daily showers, cooked all our food on an electric stove, the freezer/fridge(s) were old an inefficient... Winter time we were up to a consumption of 120 kWh per day (!) when temperatures were low. Over the winter months the average was about half of that. There is no way whatsoever that we could have had that amount of energy stored in a battery bank charged during the summer months.
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C-P-User-3 wrote: Can these systems truly power the common residence today ?
Depends on what you mean.
Often solar installs exist in two ways.
1. To provide some power to house when light is available
2. To provide all power to the house and sells the excess back to the utility when light is available.
In both cases the utility still provides power to the house either during the day or definitely at night.
For your long list the house would be drawing power from the utility. But the usage would be, on average, outside of daylight business hours because business uses along with just more people doing things at day use the most power during the day. But even so most of the time you would not be using all of those.
The third install type is more complex, costs more to install and maintain and often only exists in locations without utilities. Those installs require both solar and batteries. Solar charges the batteries during the day and batteries provide the power for the rest of the time.
Any system would of course be sized to the house and with the last option one choose as a lifestyle to make certain trades offs to lower costs. Such as limiting when laundry is done (turning off other appliances completely when running the washing machine.)
Obviously for any of the above additional back up power supplies could be in use such as gasoline/diesel powered generators.
C-P-User-3 wrote: Now then, if we can get 85 Lumens per watt from these new fangled bulbs, and if we can get a solar system that delivers lower voltage (e.g. 12 volts; whatever)
Lights are not the biggest power users in a normal house. However they are not normally trivial either. But on average I suspect load estimates for an install would not change substantially if all bulbs were the most effective possible.
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Ok fair warning, I got my rose-colored glasses on right now. It's that positive music link below I tell you. It's getting to me...
Can't...
Resist...
The Smiley...
See!?
It seems to me life is amazing stuff. Yeah we got ups and downs, but all-in-all it's a wonderful experience. Especially since the alternative is death. I think when it starts to really suck is when we neglect certain basic human needs. Like when we sit way too much behind a computer or playing video games instead of chatting with someone you like. Or perhaps spend too much in the soapbox. Ok, that's not amazing. But still, life...
What's the point of this post? None! Except to say it's good time to smile when being the holidays and all.
Jeremy Falcon
modified 5-Dec-17 1:56am.
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Pass whatever you're having. I could use it.
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Sure thing man... (takes a puff) Here ya go...
Jeremy Falcon
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What ever you are smoking, pass it over to me. 
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I look forward to moving back to a country that does not throw you in jail for smoking that stuff.
Never underestimate the power of human stupidity
RAH
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There's no law against smoking your socks! 
(Sorry Jeremy - I'll get my coat.)
Get me coffee and no one gets hurt!
modified 5-Dec-17 6:46am.
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Jeremy Falcon
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There will always some sort of substance that's controlled. If it's not weed, it's something else. We as humans need stuff to argue about... saves us from being bored and actually having to study apparently. People need an escape... whether it's entertainment, weed, booze, pr0n, cocaine, TV, or whatever. Some people need this escape so bad that all rational conversation is left out of it in my experience.
That being said, regardless of the taboo du jour, I do think a natural high is the best one. Substances are a pale comparison to doing life correctly and living on a natural high. And by natural I mean a hormonally induced, internal high.
Jeremy Falcon
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Jeremy Falcon wrote: Especially since the alternative is death.
Have you tried it ? What if it turned out to be the ultimate smile ?
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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You might be on to something. I've never heard of anyone actually coming back and complaining about it.
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Ha. And while this may be true, I'm in no hurry to find out. Besides, we have all our deaths to be dead. May as well enjoy the ride to get there.
Jeremy Falcon
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Something in the Lounge worth reading. Well done.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
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