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I was looking at some Solar Energy stuff.
The question in my mind: Can these systems truly power the common residence today ?
I'm thinking, it's easily conceivable that the normal home today can be running these appliances all at once; particularly in the late afternoon and evening...
- Washer
- Dryer
- Stove
- Oven
- Microwave
- Water Heater
- HVAC (in all its variations)
- Computers
- TVs
- Vacuum Cleaner(s)
- Refrigerators and Freezers
...and I'm sure my list is incomplete.
I'm wondering (and asking those who have electrically minded brains which are superior to my own) is the extant 120 Volt grid a factor in all this ?
I just bought a bunch of LED replacement lightbulbs last month. My guess is that, bang for the buck, the point of max economy today is about 80 or 90 Lumens Per Watt.
(I welcome correction on that figure; it's based on my observation of a local grocery store's shelves.)
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) yet higher current (big "ifs",,, I know) then do I have a workable science turned business model ?
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There are quite a few videos on YouTube to watch to get you started.
A LiIon battery pack is the best way to go. Also its better to use series connections for batteries and solar panels and go for a 36v, 48v or even higher DC system to keep the current lower, its more efficient that way.
MPPT charge controllers are very efficient at higher voltages, and depending on how much you spend you can get a lot watts out of the system.
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With 12VDC instead of 120VAC with a constant P(consumer) (which is almost realistic with modern switching PSUs) the required current rises by a factor of 10. Which means the voltage drop across the power line rises by a factor of 10. Which means the power loss across the power line rises by a factor of 100 (P = U*I -> P = R*I*I -> P = R*I²).
This is a bit simplified but good enough for illustration. Low voltage supply lines only make sense for either really small currents or really small distances. House supply is already too big, in both current and distance. In order to not turn the power line into the house heating unit you would have to increase its diameter considerably which is both expensive (copper) and unpractical in terms of installation.
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson
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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.
I obviously know practically nothing about electricity, we installed solar and I only then found out the house we bought has 3 phase power and therefore I needed to know what the hell it is. Now I'm looking for and efficient 3 phase battery solution.
Never underestimate the power of human stupidity
RAH
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Mycroft Holmes wrote: Following that logic would 240VAC be better than 120VAC
It is, at least in this regard. That's also why the the power grid operates on an even higher voltage and only gets transformed down shortly before reaching the consumer.
Mycroft Holmes wrote: Now I'm looking for and efficient 3 phase battery solution.
No experience with that, sorry.
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson
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The 120 V makes sense if you can get 120 V appliances easily - like the OP in the US.
As for your 3 phase, it prolly means that a few of your machines run on it. Most machines (e.g. microwaves) and all lamps and household sockets are only connected to 2. Maybe an option in your case could be to leave the 3-phase-machines on the grid, and build 2 phase solar system for others. I never heard of a 3-phase-DC/AC-converter but 2-phase-ones are easily found.
... such stuff as dreams are made on
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You can get a reasonable lumpy DC supply from three phase with a suitable capacitor and that gives you the ability to run arc welders, lighting stantions (out door concert lights) all sort of big boy toys that you probably not want or need in your life, however a lumpy dc with near 100 amps means you could charge Tesla's with ease. Nice to have but you will pay over the odds to get kit that uses it safely keep with the safer more manageable 240v instead of 415v, you could use one phase for charging the battery pack, the other two for running the house. 
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Charging your home and your Tesla on solar? Only if your roof is big enough. 
... such stuff as dreams are made on
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I have seen some Aircraft Hangers suitable, however the heating bill in the UK would be a down side...
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In direct sunlight and no obstacles, the inflowing solar radiation may go up to roughly 900 Watt per square meter. That is at mid-day, sunlight taking the shortest way through the atmosphere; in the morning or late afternoon the radiation slopes through maybe 2-4 times as much air, and is significantly weakened. Photoelectric solar panels usually are 18-21% efficient, so don't expect more than 175 Watt/m2 even at midday. So it takes 6 m2 of panels to collect 1 kW (if you like: 1 kWh per hour )
That is if the panel points directly to the sun. It doesn't. If the angle between the panel's orientation and the sun is v, the energy collected is cos(v). If your panel is laying flat on your roof, and the sun is 60 degrees over the horizon, the theoretical influx is 150 W/m2. When the sun sinks to 30 degrees, influx drops to 85 W - but that is for the geometrical aspect only; the atmospheric loss comes in addition.
When the angle increses, there is a third loss: At a microscopic level, the active element is not at the very surface, but lies in a "dip" or "valley", with "mountain sides" that may fully or partially shade it, reducing yield even furhter than cos(v) indicates.
Yet another loss, caused by the way the cells are hooked up in a panel, in long chains: If a shadow falls on parts of a chain, e.g. from a tree branch, or a dry leaf landing on the panel: Even if only a few percent of the cells in the chain are shadowed, this will to a large degree choke the entire chain.
Then you have the large "shadows": The clouds. How many hours of sun do you have during a year? That varies a lot from country to country, and from coast to inland, from lowlands to highlands. Photoelectric cells definitely do best in sunlight; they do have a yield even in cloudy weather with diffused light, but far less.
So, the bottom line: In Sahara, California etc. where you have no need for heating, and you can have your batteries recharged every single day by at least eight hours of bright sunshine, you might cover your entire roof with solar panels, and you can probably go completely off-grid. Here up by the polar circle, you would have to cover your entire garden with panels, and fill up your basement with Li-Ion batteries to get through the winter. (That is after you have found that gold mine for paying the investment...).
Solar is fine for low-effect uses, like light, alarm systems, communication, as well as for emegeny use. If you want to go completely off-grid, think of alternate solutions, like thermal heat collectors for heating (at least 4 times as efficient as photocells), cooking on gas etc.
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USA did not follow UK standards! UK standard is 240volt for standard domestic supply and 440volt of 3 phase.
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Well 240 is the old now you can get anywhere from 227 to 250 out your wall socket thanks to the fact the EU use 230 (with no earth!) and the 'easyest' way was to relax the standards. Not really an issues as most devices like washing machines will take 220-250 to make life easier for the manufacturer and most things that don't use motors have a switch mode power supply...(just to make life awkward for RF engineers...) 
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glennPattonWork wrote: 230 (with no earth!) and the 'easyest' way was to relax the standards.
No Nanny State Safety Standards for you guys in the EU !
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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Quote: No Nanny State Safety Standards for you guys in the EU !
My dear chap, former EU (!?  )
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Mycroft specifically mentioned Australia, not Merka. Reread his post.
Michael Martin
Australia
"I controlled my laughter and simple said "No,I am very busy,so I can't write any code for you". The moment they heard this all the smiling face turned into a sad looking face and one of them farted. So I had to leave the place as soon as possible."
- Mr.Prakash One Fine Saturday. 24/04/2004
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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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