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Is it possible to power a home with 120 volts DC?
Home Powerd By DC?
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kb0nly
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120v DC??
12v DC you could... I mean you would have to go to great lengths here, but its entirely possible. You can get propane/dc refrigerators like they use in RV's, cooking could be done with propane, heating could be done with propane heaters that have 12v thermostats and fans. All your lighting could be switched over to DC LED lighting, and even 12v CFL, the RV market has plenty of choices there. It gets trickier depending on what you want for appliances. But you could run a laptop off a 12v auto/air adapter, some LCD TV's could be run off 12v instead. I mean it all depends on how far you wanted to go, but think of a RV/Camper with a 12v electrical system. If it can't be run off 12v you run off propane, water heater, stove, furnace would be examples.
So yes its possible... Would be expensive to convert of course, but if you had sustainable resources like solar and wind power to keep a large battery bank charged then you could. Also with those systems you can run a power inverter as well if you need AC.
I would love to have my house "off the grid"...
12v DC you could... I mean you would have to go to great lengths here, but its entirely possible. You can get propane/dc refrigerators like they use in RV's, cooking could be done with propane, heating could be done with propane heaters that have 12v thermostats and fans. All your lighting could be switched over to DC LED lighting, and even 12v CFL, the RV market has plenty of choices there. It gets trickier depending on what you want for appliances. But you could run a laptop off a 12v auto/air adapter, some LCD TV's could be run off 12v instead. I mean it all depends on how far you wanted to go, but think of a RV/Camper with a 12v electrical system. If it can't be run off 12v you run off propane, water heater, stove, furnace would be examples.
So yes its possible... Would be expensive to convert of course, but if you had sustainable resources like solar and wind power to keep a large battery bank charged then you could. Also with those systems you can run a power inverter as well if you need AC.
I would love to have my house "off the grid"...
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sure you can do it, 12v or 120v DC will work just fine WITH THE RIGHT EQUIPMENT. you cannot run an AC motor off DC so you either need large inverters or DC appliances. incandescent lights are no problem, they don't care if it is AC or DC but do require at least 120V to be proper brightness. CFL will have to be made for DC, you can't use regular off the shelf CFL bulbs.
the first thing off the grid houses do is eliminate any unnecessary power drains. use solar for water heating, geothermal HVAC systems or if the climate is right no AC and wood burning heat so all you have to power is some fans.
the first thing off the grid houses do is eliminate any unnecessary power drains. use solar for water heating, geothermal HVAC systems or if the climate is right no AC and wood burning heat so all you have to power is some fans.
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They sell DC to AC inverters? *** Never mind. I forgot I have a few :lol: So a motor could run off of an inverter no problem? I suppose you would need one with adequate peak amps.
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kb0nly
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Heck yes, inverters of all kinds.
From 12-60v DC from what i have seen so far, wouldnt doubt there is more than that also. Everything from a few hundred to thousands of watts for output. I was looking at one setup a while back that uses solar panels and a huge battery bank at 60v DC and a grid connected inverter. Whatever power they arent using they backfeed the grid and spin their meter backwards selling power to the grid.
From 12-60v DC from what i have seen so far, wouldnt doubt there is more than that also. Everything from a few hundred to thousands of watts for output. I was looking at one setup a while back that uses solar panels and a huge battery bank at 60v DC and a grid connected inverter. Whatever power they arent using they backfeed the grid and spin their meter backwards selling power to the grid.
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yeah a motor can run off an inverter, it just has to be big enough. the startup current rush of a motor can be many times the running current and the inverter has to be able to handle it. it won't be cheap up front, but if your electric costs are high enough it may eventually pay for itself before time to replace the inverters. batteries are going to last you 2-3 years on average, don't forget to factor in the cost of replacing them when planning something like this!
"Is it possible to power a home with 120 volts DC?"
Only if you could find 120VDC appliances, only those with bimetallic thermostats and resistance heating elements and incandescent bulbs would work, those have been banned and stocks running out. Then many appliances use induction motors and transformers which represent almost a dead short to DC so you'd fry more than half the equipment in your home.
"yeah a motor can run off an inverter, it just has to be big enough. the startup current rush of a motor can be many times the running current and the inverter has to be able to handle it."
Starting current is approximately 600 times running current.
Not only that but it would have to output a stepped sine wave, adequately handle an inductive load and be frequency stable. Those are horribly expensive, ones intended for general use get upset by inductive loads and exhibit frequency runaway squealing like a pig as the output falls to an unusable value. FYI, any motor, even series wound universal motors such as found in vacuum cleaners and shop tools are inductive loads.
If you're thinking of solar or wind power the package is quite expensive not to mention maintenance costs, there's no cheap way to do it.
Only if you could find 120VDC appliances, only those with bimetallic thermostats and resistance heating elements and incandescent bulbs would work, those have been banned and stocks running out. Then many appliances use induction motors and transformers which represent almost a dead short to DC so you'd fry more than half the equipment in your home.
"yeah a motor can run off an inverter, it just has to be big enough. the startup current rush of a motor can be many times the running current and the inverter has to be able to handle it."
Starting current is approximately 600 times running current.
Not only that but it would have to output a stepped sine wave, adequately handle an inductive load and be frequency stable. Those are horribly expensive, ones intended for general use get upset by inductive loads and exhibit frequency runaway squealing like a pig as the output falls to an unusable value. FYI, any motor, even series wound universal motors such as found in vacuum cleaners and shop tools are inductive loads.
If you're thinking of solar or wind power the package is quite expensive not to mention maintenance costs, there's no cheap way to do it.
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kb0nly
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The solar cells themselves are getting cheaper. There is a company now that makes a flexible peel and stick solar cell film that can be applied to metal roofs. You put on metal roofing with 16" exposure and you buy the rolls and peel and stick. There is some tech schools around me using that system and have been for years without issue. They run a battery bank with grid connected inverter. Total install cost was about $30k, but they made that back in energy savings running everything off of it and selling the excess to the grid in the first few years. Not too bad in my opinion!
There is also the Unisolar shingles now too. I'm considering the option of putting in a large area of solar shingles when i need a new roof in the next few years.
There is also the Unisolar shingles now too. I'm considering the option of putting in a large area of solar shingles when i need a new roof in the next few years.
There are probably better ways to do it than 120 vdc. How you go about it would depend on what exactly you have in mind. Back up power? Full time off the grid? Just trying to be different? Trying to prove Tesla was wrong about ac?
I got no clue on this! Most web explanations seem to ignore Watts, and the few that had something, I wasn't able to relate it to what I found about Amps and Volts (just some complicated mathematical relationship). Is there anything I should know about Watts that would help me match up laptops ac adapters?
Laptop AC Adapters, Replacement Laptop AC Adapters, Cheap Laptop AC Adapters
I got no clue on this! Most web explanations seem to ignore Watts, and the few that had something, I wasn't able to relate it to what I found about Amps and Volts (just some complicated mathematical relationship). Is there anything I should know about Watts that would help me match up laptops and suitable adapters?
idontknow82
Member
I wouldn't recommend 120 vdc, if you were to get a shock you more then likely wouldn't
be able to let go. You would need an inverter to power house hold stuff.
kb2vxa=NJay? ...A person can start out with a small system and work there way up.
be able to let go. You would need an inverter to power house hold stuff.
kb2vxa=NJay? ...A person can start out with a small system and work there way up.
"I got no clue on this! Most web explanations seem to ignore Watts, and the few that had something, I wasn't able to relate it to what I found about Amps and Volts (just some complicated mathematical relationship)."
Nothing complicated about it; EI=P
E = volts
I = amps
P = power or watts
Note: E stands for electromotive force but some express it as V for volts. Likewise for power, some express it as W for watts.
That's part of Ohm's Law for DC but good enough for government work. If spot on accuracy is required for AC use VAR or volt-ampere resistive. The internet has a lot to say about Ohm's Law but you have to crack some electrical engineering books for VAR since it's rather complicated high math... and it's all Greek to me. (;->)
Nothing complicated about it; EI=P
E = volts
I = amps
P = power or watts
Note: E stands for electromotive force but some express it as V for volts. Likewise for power, some express it as W for watts.
That's part of Ohm's Law for DC but good enough for government work. If spot on accuracy is required for AC use VAR or volt-ampere resistive. The internet has a lot to say about Ohm's Law but you have to crack some electrical engineering books for VAR since it's rather complicated high math... and it's all Greek to me. (;->)
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What about Coulombs buddy! :lol:
n0nhp
Member
I lived for two years in a ~120VDC house, completely off the grid. 57 2V 2KAH cells in the battery room!(with full charge being 2.2V per cell, 60 would take out thing like light bulbs)
Rules posted at the door:
NO SMOKING WITHIN 50'
ONE HAND IN THE POCKET AT ALL TIMES
The swamp cooler had a brush type motor. The vacuum cleaner was perfectly happy.
As has been pointed out, incandescent light bulbs lasted nearly forever as there was no AC to cause the filaments to vibrate and break.
This was before I got into computers, but they would be perfectly happy with their switching power supplies. The old GE TV I had did basically the same thing as a switching PS by rectifying the AC and using the flyback transformer for all it's internal voltages. The only thing that didn't work was the remote control, it was powered by a separate transformer and that had to be disabled.
I also had 48VDC run for things like the toaster and electric blanket. They wouldn't heat as quickly as they would running 120VAC but the contacts wouldn't arc-over. I also had 12VDC run for scanners and radios. The way the system regulated it's self, I would change that to a 12V switching power supply to help keep the system balanced. If you load a lower portion of the bank, it looks like a lower resistance when charging and the top end will over charge. I would switch the whole solar array to the 48V portion of the batteries about one day a week to help balance the bank.
For AC only appliances, I had an old military surplus Dynomoter, it ran on DC 50 to 200V and produced a very clean 120
VAC 60Hz (it would fall off in freq just a bit when the old microwave would kick in). I usually waited for a nice sunny Saturday or Sunday to do laundry (the advantage of being a bachelor with several weeks worth of clothes).
If life had turned out a bit differently I would still be living that way, off the grid with DC as my main power source.
Ahh well, coulda shoulda woulda.
It is not the life for a family unless all parties involved like tinkering and putting up with inconveniences, I spent my whole weekend maintaining the battery room and solar tracker, the windmill pumping the water and many many other little things people who dream of living off grid don't think about. I was a kid in a candy store!
[/NOVEL]
Bruce
Rules posted at the door:
NO SMOKING WITHIN 50'
ONE HAND IN THE POCKET AT ALL TIMES
The swamp cooler had a brush type motor. The vacuum cleaner was perfectly happy.
As has been pointed out, incandescent light bulbs lasted nearly forever as there was no AC to cause the filaments to vibrate and break.
This was before I got into computers, but they would be perfectly happy with their switching power supplies. The old GE TV I had did basically the same thing as a switching PS by rectifying the AC and using the flyback transformer for all it's internal voltages. The only thing that didn't work was the remote control, it was powered by a separate transformer and that had to be disabled.
I also had 48VDC run for things like the toaster and electric blanket. They wouldn't heat as quickly as they would running 120VAC but the contacts wouldn't arc-over. I also had 12VDC run for scanners and radios. The way the system regulated it's self, I would change that to a 12V switching power supply to help keep the system balanced. If you load a lower portion of the bank, it looks like a lower resistance when charging and the top end will over charge. I would switch the whole solar array to the 48V portion of the batteries about one day a week to help balance the bank.
For AC only appliances, I had an old military surplus Dynomoter, it ran on DC 50 to 200V and produced a very clean 120
VAC 60Hz (it would fall off in freq just a bit when the old microwave would kick in). I usually waited for a nice sunny Saturday or Sunday to do laundry (the advantage of being a bachelor with several weeks worth of clothes).
If life had turned out a bit differently I would still be living that way, off the grid with DC as my main power source.
Ahh well, coulda shoulda woulda.
It is not the life for a family unless all parties involved like tinkering and putting up with inconveniences, I spent my whole weekend maintaining the battery room and solar tracker, the windmill pumping the water and many many other little things people who dream of living off grid don't think about. I was a kid in a candy store!
[/NOVEL]
Bruce
WA1ATA
Member
Ignore 'em. They just go with the flow.
More seriously, 1 ampere is 1 coulomb of charge per second. So a coulomb is the number of electrons that flow past a point in one second at 1 amp. (Or in 1/10 of a second at 10 amps, etc.)
Mike_NZ
Member
Another problem with DC current is that it is harder to switch than AC.
AC current has the natural current zero every 50 or 60 seconds, DC doesn't have that, so you'd need substantial switches to quell the arc generated when you go to switch your lights off.
DC used to be used in some parts of Aussie years back, I remember reading an article in a popular electronics magazine from there about a guy in that era that used an AC switch on a DC system, an arc travelled out of the switch box, up the wiring on the wall (surface wiring in them days) and never stopped until it got to the lamp-holder in the middle of the ceiling, where it blew the wires out of the lamp-holder terminals.
This stopped the arcing, anyway.
AC current has the natural current zero every 50 or 60 seconds, DC doesn't have that, so you'd need substantial switches to quell the arc generated when you go to switch your lights off.
DC used to be used in some parts of Aussie years back, I remember reading an article in a popular electronics magazine from there about a guy in that era that used an AC switch on a DC system, an arc travelled out of the switch box, up the wiring on the wall (surface wiring in them days) and never stopped until it got to the lamp-holder in the middle of the ceiling, where it blew the wires out of the lamp-holder terminals.
This stopped the arcing, anyway.
Token
Member
I assume this 600 number is a typo?
The starting current, or locked rotor current, should be about 5 to 6 times the loaded running current, maximum. Also remember that if you current limit this you can still start the motor, it is just going to start slower, and you might want to start unloaded if possible. And you can also build a soft start for many motor applications.
Sine wave inverters are not all that expensive. True, they are a good bit more expensive than the cheap square wave models sold in some places, but still not very bad, think along the lines of 3 or 4 times the cost. I think my 2500 Watt (4.2 kW surge) Xantrex was under $900 USD. Yeah, I know you can get a square wave inverter of the same Wattage for about $250-300. Oh yeah, and my inverter regularly starts and runs a 1 HP single phase motor.
I have been doing solar power for remote applications (such as repeater and remote facility sites) at work since around 1990, some of them have been quite large, over 200 kW. I have had a solar backup setup at home since around 2000 or so, not big enough for the whole house, but large enough to keep the important stuff running.
You are right, it is not cheap. Even if you can get the solar cells for $4 or $5 a Watt ($3 or less a Watt in larger systems) the rest of it cost a pretty penny. 4 kW 240 VAC systems with storage cells are going to start in the $20,000 area, not including installation. And that is going to be a pretty minimal system, but might be eligible for tax rebates. If you really take care of your batteries you can get between 7 and 10 vears out of them. One of our 200 kW systems went 14 years before enough cells had failed that we had to replace the banks, but that is an exception...and we had air conditioning and heating on the battery building. Temp variations play a huge part in battery life when talking about lead-acid. For my small back-up system at home I plan for 6 year battery life, and that is what it has worked out to. The PV cells themselves have a life of over 20 years.
T!
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