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Sharp Announces Sales of DC Powered Air Conditioner, Other Products To Follow
AmiMoJo writes: Sharp has announced that sales of DC powered air conditioners will begin by the end of the year. Most appliances use the standard AC electricity supply in homes, but as solar panels become more common switching to DC can save on conversion losses. Solar panels produce DC, which is then typically converted to AC before being fed into the house's wiring, and then converted back to DC again by appliances. Sharp has announced that it intends to produce a range of DC powered appliances for home use.
Nikola Tesla is turning in his grave.
No sig today...
Wouldn't it be possible to have both in the same appliance?
Noticeably missing from both linked TFAs. As discussed here and elsewhere previously, 48V would probably have too much ohmic loss unless this A/C is right next to the supply. Higher voltage would work better, but call into question safety issues you don't have with AC due to it passing through zero volts 100-120 times a second.
The will arrive just after my goose lays the first golden egg.
Time for bed, said Zebedee - boing
Even when they take DC, a lot of them are different voltages. Phone / USB chargers are 5V. Things like Laptops will be ~20V. So you will still have conversions. And the power going around, 120V or 240V, allows you to run moderate sized appliances without ridiculously thick cables. High voltage, low current, rather than low voltage, high current.
This is it exactly. 5V for usb, 1.5 V for the processor, 48 volt for the back light, etc. and what about things like your stove, refrigerator etc? things that use AC power for their motors.
you get 120/240V at every outlet, you can then convert it to any voltage you need fairly easily. if you are running 48V DC it is a lot harder to convert that down to 5 V.
i thought once I was found, but it was only a dream.
I love it, a DC AC
Too complicated energy pathways. You can't power everything by heat. If your cooling needs are saturated, you can't power anything else with it. So you need a parallel supply of electricity again. And once you have it, why the redundant heat engine in the first place?
Ezekiel 23:20
Re "On a more serious note, what are the benefits/costs of using AC over DC in the home?"
AC gives you the national grid, hydro, power stations and epic scale.
DC gives a solar setup one less DC to AC to DC loss conversion to get the same result in the home setting (lots of roof panels, sun, short DC wire length to correctly sized air con unit).
Re: Do modern TVs run on AC, or are they just converting it to DC internally as well?
A boat, RV or truck shop can help with a list of DV 12v and 24v devices. Wire thickness, length, amps, devices used, storage then gets to be interesting design cost in the home setting.
With AC within reason any electrician can give you a great deal of "power" from the grid, 24/7 per room. With DC the length, width, usage, voltage math starts to get more interesting per device added.
Domestic spying is now "Benign Information Gathering"
The main advantage of AC is that you can use higher voltages safely, and higher voltages mean higher wattage with the same wires. And bigger wires are more expensive.
AC versus DC load breaking comparison with a knife switch
That was 220 volts, but 110 volts isn't much better on the DC side. There's a reason why DC-powered telecoms equipment uses 48 volts; much more than that and switches start arcing.
Ohmic loss is an issue when DC power is transmitted over power lines, but not so much when the DC is generated in the same building (solar panels, etc.).
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DC gives you efficient long-range transmission. I.e., that "epic scale" you spoke of.
Ezekiel 23:20
I'm pretty sure most of those DC-DC converters (the modern efficient ones) work by converting to high-frequency AC internally, running it through a transformer (higher frequency = smaller transformer), then back to DC.
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Yes looking up from a home setting AC? Or down the grid (HVDC). https://en.wikipedia.org/wiki/... and https://en.wikipedia.org/wiki/...
The DC air conditioner might still be interesting with a savings % on site for solar been more direct and less AC to DC conversion loss.
Domestic spying is now "Benign Information Gathering"
Thanks for linking that -- great demo.
Watch this Heartland Institute video
The size of such a chip and the heat dissipation requirements would mean you would only want to use it for the higher end applications.
I've been saying for a few years that if you just had a few solar panels in your back yard, and didn't want to go through the expense of all the inverter stuff, you could just use it to charge a small battery and power a DC air conditioner. That's because you generally want air conditioning at the same time that you have the most solar power. At the time, the only DC air conditioners available were for marine use, and so they were expensive. However, in the last year and a half I noticed a lot of DC air conditioners on the marker on AliExpress (in China). Some of them even come as a kit including solar panels. The difference here is that presumably the Sharp ones are UL and/or CSA certified, so you could use them in North America.
Honestly, some of the stuff on AliExpress is impressive for how cheap it is. You can buy 500W grid-tie inverters for a solar array for the $200 range. Unfortunately they only have a CE rating, so they're not OK for North America yet. In comparison you can spend 3 to 4 times that much here.
"I have never let my schooling interfere with my education." - Mark Twain
Is this not just a change in power input but a substantially more energy efficient air conditioner, too?
I've seen small A/C systems for cars and marine applications that can run off DC power, but they're usually pretty small which helps cut the overall power consumption. In marine applications they also have the advantage of being able to use sea water to move the heat versus a fan and coils in open air.
One of Sharp's smallest split system units has 8500 BTU of cooling with an EER of 13 which is roughly 650 watts. That's about 14 amps @ 48v, 27 @ 24, and a battery sucking 54 amps at 12v (run with welding cable).
8500 BTU might cool a room reasonably well, but its not going to provide whole-house cooling, either, and would require a pretty large battery array to run off battery. It might make sense for some kind of supplemental cooling setup where it ran direct off solar panels.
Well, I think we are getting better at converting DC voltages, which is why HVDC is being used for transmission lines for example.
I suspect the reason is in part portable electronics. We're trying to eke out as much power as possible for multivoltage devices (one voltage for the processor, another for the screen, another for the HDD (portable electronics includes laptops too...) another for the USB bus, etc) from a single (DC it goes without saying) battery. The amount of R&D into the voltage conversion field over the last thirty years must have been extraordinary, yet not sexy enough to warrant much media coverage.
You are not alone. This is not normal. None of this is normal.
They use inverters to convert the DC to some square wave and approximate it to A/C using electronic gimmicks. Not a pure sine wave A/C, but close enough to run fans and the lamps. Energy conversion efficiency is not bad, the inverters do hot heat up too much. But they play havoc with the motors. So the Japanese A/C makers have been selling ruggadized air conditioners that can run on the inverter electricity.
The logical next step is to create A/C to run purely on DC. Probably it would use AC to DC converters to use grid electricity. Again this DC would be poor in quality compared to battery DC. So this Aircon also would need to be ruggadized.
All these calculations about when residential solar will become viable compared to coal or natural gas are completely different between G8 and rest of the world. Places like India will pay well over the current grid price for steady electricity supply. Not all of them. But the affluent population of India is about the size of Japan, some 120 million people. They have been making do with truck-battery-inverter contraptions, small gasoline generator sets etc. They would probably form the wave of early adopters who pay for the early fixed costs of solar panel factories.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Compare size of fixed-voltage adaptors, to those able to cope with 110v/240v output.
Compare size of fixed-output adaptors to "multi-output" adaptors. Some laptops ones are tiny. All the "generic" adapators are huge.
And that's with a handful of options, maybe 2 options on the input and 3-4 on the output. Now combine sizes. Now add in an input capable of the DC (yes, you can Wheatstone bridge the AC, but that's got to be using diodes big enough for anything you put on). Now add intermediate paths capable of the MAXIMUM current that goes through it, as DC, all the way, down to the minimum voltage (i.e. if it can output 1v, that's going to give 12 TIMES the current that outputting at 12V would give, needing seriously large cables and intermediate circuitry for any practical purpose (even 30W, at 1v, would give 30A ratings... 30A DC @ 1V needs 120mm thick cable for a 1m run).
Even adjusting for "reasonable" voltages up/down, you're also expecting up and down conversion (i.e. mains to 12V and also 12V to 48V), which is rare to see in the same device.
Basically, the thing would be as huge and heavy as a car battery, get fucking hot, be prone to failure, and require internal circuitry and insulation from the power paths that's just not practical. And it would probably be quite inefficient across whole ranges of voltages.
You can't have some tiny 5v chip controlling a variable output of that kind of size without some huge, specialist "break open a UPS and see the kind of size we're talking about" components in it, with thick paths between them.
Honestly, the first thought that comes to mind is "fire", quickly followed by "fucking expensive". There's a reason that you set a standard and follow it and try not to change that standard (hence why half the world refuses to change to the other half's mains voltage). The conversion equipment is then static, and makes it practical. And there's a reason that 100+ Volts emerges as the winner every time, because you can get decent power down a decent sized cable.
Hell, even 12V DC / 240V AC input devices are "rare" in modern life compared to everything else - motorhomes and marine use, pretty much, and expensive and sometimes several years behind the technology. And internally all they do is convert to one or the other, so it's really just a TV and a convertor in a box wired to the same 12V DC input on the actual TV (which almost certainly then boosts the voltage for it's LCD panel) because that's easier to make than some generic device that can take in anything and shove it where it wants in whatever format it wants.
Fuck, even inverters or voltage convertors (110/240V) as standalone devices for generic use are bricks that weigh a ton, cost a lot, and have very limited power output.
So you're saying it's impossible to do an arbitrary DC/AC to DC/AC without a massive efficiency penalty?
Is it just my observation, or are there way too many stupid people in the world?
I've long thought that whole local power grids would switch to DC eventually anyway.
Unlikely to happen any time soon. Too much installed base of AC power. Not like people are going to rip open their walls to switch from AC to DC and virtually everything you plug into the walls is designed with AC in mind. The only wide spread DC cabling standard is USB and that's mostly low power stuff.
I have no principled objection to DC power but I think any switch will take many decades if it happens at all.
The competition for good DC-DC conversion is reasonably fierce(given the existence of DC telco and datacenter operations, and the fact that even 'AC' shops are really just doing the conversion in each chassis(and unlike the old AT PSU days, an ever larger chunk of the output power is 12v going directly to a DC-DC converter on the motherboard to feed the CPU and RAM, with fewer and fewer components, aside from HDD motors, being sufficiently high voltage to feed directly from the PSU); so even modest improvements in DC-DC efficiency would make you quite wealthy indeed.
I haven't kept a close eye; but I think that the present standard for DC-DC modules still uses a number of off-chip components(whether because the needed capacitance and such simply can't be done in silicon, or are cheaper as discretes, I don't know); but you can get some very, very, dense little modules.
what voltage do they expect? 12 volts? 48 volts? 100 volts? can i use my 2 AA cells?
now we need to go OSS in diesel cars
So what happens when their home system craps out? Can the unit run when they pull AC power from the grid?
"A plan fiendishly clever in its intricacies"- Homer Simpson
Of course you can power everything with heat. Indeed, nearly everything *is* powered with heat; Most conventional power plants use thermal processes, converting heat energy into mechanical energy then into electrical energy.
A solar powered refrigerator (or any refrigeration cycle driven directly by heat) allows the use of fairly low quality heat sources to do useful work without losses converting it to electricity first. Very useful in some circumstances.
=Smidge=
The trend in solar is to put mini inverters on the panel itself giving them an AC output. This makes the setup and wiring of an array much easier and cheaper.
I was literally thinking about this problem the other day.
I was day dreaming about the idyllic rustic life living in a cabin in the woods away from civilization etc... Then I got thinking, you know what? I would hate that, this week the temperature has been hovering around 32-38 degrees, which is hot. Sitting in a hot cabin all day doesn't sound so romantic, nor does hiding in a lake all day. AC is pretty much out of the question, as I'm pretty sure it would be too inefficient and drain whatever power you have in short order...
However DC AC (lol new Aussie band name?) might work better. Presumably when it is hottest out when you want AC, it will also be very sunny for your solar panels, which if more less feed directly into your AC might work out better.
Anyway it all sounds rather interesting... OK I'm off to start day dreaming about unrealistic rustic off-grid living again!
There is no way to supply a high-power appliance (such as an AirCon) directly out of a PV array. None.
The panel is always operated at a point (MPPT) where it produces the most power, but that power is highly fluctuating whenever there's a slight obstruction in the incident sunlight (clouds, stray leafs, even passing birds).
You need a DC/DC power converter feeding a battery array. Then the DC appliance can be powered from that battery pack. Overall, an expensive solution mostly due to the need of local energy storage.
They have them, but the converion process requires some amount of energy storage which can't be done at wafer scale without dielectric breakdown.
But buck converters do operate by converting to high-frequency AC internally, running it through a transformer (higher frequency = smaller transformer), then back to DC.
I, for one, am disappointed to not see you modded :)
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So, can anyone explain how this is going to affect LED lightning etc.?
I remember reading something about the changing load on AC due to the adoption of LED/CFL instead of bulbs (spike usage).
Will a central DC unit in my house run LED/CFL more efficiently?
I don't turn on the A/C until late in the day when i get home from work and the sun is already at a low angle. I suppose if I had a Tesla battery to go with my PV system it'd make a bit more sense...
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You're forgetting that AC is significantly more efficient at driving a motor than DC is. Go look at any good power tool, washer, drier, they all require dual phase AC for a reason.
This is a step backward.
Efficiency is not so much as a problem as cost. It is easier to design converters with specific input and output voltages.
Converters commonly have a fixed output and 2:1 input voltage range which covers universal input power supplies with a 120 through 240 AC input . Converters with a 4:1 input voltage range are not as common but are available for a price premium. 10:1 input ranges are rare.
The problem with large input and output voltage ranges is that for the same power, the electronics have to handle both high voltage at low current and high current at low voltage making the design less optimal, less efficient, and more expensive.
More wealthy folks also used domes and towers with windows at the top for the thermal siphon effect. Some even had and gas flames near the windows to enhance the siphon. One of the This Old House episodes showed an example of the type with gas flames.