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Direct current electricity could cut power bills, claims creator

The creator of a home electricity system that uses direct current claims it could cut users’ bills by up to 30 per cent.

Moixa Technology this week unveiled its Smart DC network, which uses solar panels and off-peak grid electricity stored in batteries to power electronic devices in the home such as televisions, laptops, mobile phones and LED lighting.

This reduces energy losses associated with converting alternative current from mains sockets into DC (up to 45 per cent), which most small electronic devices run on, or with converting DC generated by solar panels into AC to sell to the grid (up to 15 per cent).

The network comprises solar panels, DC sockets, an electric vehicle-quality Li-Fe battery — that could power LED lights in a typical house during a power cut for a day — and a hub device that takes information from a smart meter.

This hub manages the flow of electricity according to how much energy it predicts the house will need, how much is available from the solar panels and battery and how much grid power costs according to whether it is a peak or off-peak period.

It can also use weather information to predict how much solar power it will generate the following day and store grid energy in the battery accordingly.

‘People just want cheap and efficient energy,’ Simon Daniel, chief executive officer of Moixa, told The Engineer. ‘Too much information is annoying but people will take good advice if it is specific to their situation.’

Users could save between 10 and 30 per cent on their electricity bills, he added, and an additional 15 to 20 per cent on their gas bills by adding an electronic boiler monitor that predicts gas usage and turns off the heating when it’s not needed.

The company plans to follow a business model similar to that of Sky, making the technology easy to install by local contractors and offering gradual upgrades than can be added easily.

The network will also use data on the changing price of solar panels and LED lighting decreases to tell the homeowner when it becomes cost-effective for them to install more of these products.

Moixa is aiming to make the system available for between £1,000 and £3,000 per home. Daniel estimated this cost could be recouped in three to five years through savings on energy bills.

The firm expects the system to be of particular interest to those who work from home and operate electronic devices throughout peak hours, as well as to hotels and student accommodation.

Smart DC was developed following £1.4m of research projects led by Moixa and funded by the Technology Strategy Board and the EU.

Readers' comments (29)

  • At last Edison has the last laugh DC beats AC for home use

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  • Oh and I thought it was going to another smashing 19th Century style contest between AC and DC distribution, with demo electric chair executions to show which is safer.

    How mundane! But sensible, although I do wonder about the £1.4 million on research, go down to any marina and see how 12v is the law of the land (or perhaps sea)!

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  • The small AC to DC chargers are a trivial load compared to heaters, washers and dryers and fridges, many of which would need up conversion to AC to operate.
    So this idea has a green veneer, but will not deliver these savings. Better insulation on houses and fridges, slower dryers and slower washers will save a lot more energy. Why dry in 20 minutes with 3000 watts, when you might dry in 2 hours with 300 watts and through air - the motor does run longer, I agree, but it can also be smaller, and the drum turn slower. Appliances have been made to waste energy to save us time.

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  • I really like this concept. "Keeping Electricity Local"

    Inside the home Low Voltage DC is by far a more sensible option, but be aware that electrical heating devices like kettles will still need higher voltages to deliver enough power without excessive voltage drop across normal wiring. (DC voltage changers?)

    Totally agree that 12 Volt (as in boating environments) should be the appropriate way to go.

    In reference to Peter Edwards comment, Edison had no way to deliver DC over long distance, and that was the value brought by Tesla in proposing AC power.
    With localised power generation, we don't need to transport electricity over huge distances so it makes the need for AC irrelevant, but that was not the case in Edison's time. Tesla also showed how to deliver power via radio waves making the electrical grid system irrelevant, but the high investments already made in the grid meant this was ignored.

    If they paid me £1.4m I could have come up with these results in a lot faster time.

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  • I think we need to promote 12v Products and seperate power supply for them either AC/DC to connect them with battery 12volt Dc and Main. with 12 v output from main in each home

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  • Why do we always start with "could" save. Lets have some numbers. What is the outlay in batteries for a start?
    How many barges/houseboats have we seen with alternators on there roof, going back at least 40 years.
    To actually replace all batteries in TV and Sky box remotes with a solar panel like calculators would be more benificial. That would save how many batteries?

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  • They tend to ignore the fact that the conversion losses in AC to DC for appliances isn't entirely lost as such - it produces heat which contributes to the space heating in the house. Running part of the house on DC also means rewiring and perhaps heavy copper cable. 80 years ago my village had a mill-stream powered system which provided AC during the day for machines, and DC at night for lights.

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  • Edison's system failed commercially because it only worked in local New York precincts and could not be transmitted very far. This led to lots of small, inefficient power stations throughout the city. Now we are looking again at local generation and consumption, the big electricity companies (today's Westinghouses) are not keen to promote this re-localisation. I can see this fulfilling Edison's dream as solar power doesn't have to be shipped in as coal was.

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  • @Peter Edwards
    Er, no he did not.
    After a century of development, largely made possible by Tesla's AC cheap & effective power system, we finally have DC powered gadgets that need DC, and we have cheap silicon devices to perform the conversion.
    Do you really think anyone will go for high power DC for power-to-the-home use? Too much precious metal (low voltage) or problems with circuit breakers (high voltage).

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  • I guess its fine so long as you don't want to do anything serious like run a cooker or boil a kettle. The power saved by running LEDS from 12 v rather than from the mains is insignificant.

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  • I absolutely agree with this idea. I plan to run all those things that require a low v dc such as cordless phone, mobile charger, router, burglar alarm, door bell, printer, etc. Then get rid of all the 13A plug top PSUs which sit there 24 hrs per day gently warming where I don't need heat. It would be nice to think that at night or when we are out, the electric meter was stationary. The only fly in the ointment is the different voltages that many of these things are designed for.

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  • The idea is sound technically and can be extended to run model train sets etc. But its high capital cost makes no financial sense for two basic reasons. Firstly the vast majority of electrical energy is required for heating and work loads (we are not all geeks with electronics everywhere) and, secondly, the percentage drop in electricity consummed has to be halved for money saved due to the very aggressive "reducing block tariffs" that we have for our utility bills.

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  • I don't see it happening. The conversion figures from AC to DC are worst case, and not representative of most modern supplies. In my house I have DC supplies running at 19V 3A for my laptop, down to 3.3V for my Bluetooth headphones, other voltages include 6V, 9V and 4.5V. So I would need DC-DC converters to switch all these, run my devices using non standard chargers, and worst of all if it was running at 12V around the house run thick cables because there will be voltage drops when I've got a couple of high current loads. Oh and I'll still need real mains sockets for stuff that uses real power.
    The money would be better spent on better inverter designs, and panels that can be disguised as standard roofing tiles and get better efficiency!

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  • Ok we can generate 12v from wind turbine and solar panels, but having this set up is great. Where I have run into trouble is storage i.e. batteries. The inverters are really improving of late, but the batteries are still to large and take up to much room not to mention acids etc.

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  • The problem with any DC network for home use will be getting manufacturers to agree on a standard voltage, and a standard socket/plug.
    Even if you suggest 12V with a car cigar lighter plug - as on most cars, caravans and boats - you can bet that around the corner the major car manufacturers are planning a move from 12V to 60V, or whatever, that will scupper the whole plan.
    More efficient 'plugtop' power supplies and better designed products would reduce the power wasted in so many current consumer electronic products.
    The earlier comments on washing machines and driers are good point too.

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  • I almost worked for a company that made inverters for motor home microwave ovens. Until they firmly believed it had to work at 50/60 Hz. If the oven transformer was built for 400 Hz to 5kHz. like the Ham radio DC supplies of old time, it would be much more efficient.

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  • I think what Moxia's research has revealed is that we can combine both AC and DC in our homes. Its easy to split your DB Box to have DC operate low voltage lighting, televisions, laptops, mobile phones. The AC current can always power up power hungry devices, this way if there should be an emergency you still have some resources left.

    The other issue will be to have manufacturer's of electronic components have selectable switches on their devices for choice of DC or AC use by the end user.

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  • At last the greeny boppers will get to kid themselves on they are saving the planet whilst running all the low volt must haves on DC generated on the roof for free. Add the cost of distributing the low volt DC around the house to the original ring main costs and I doubt it will catch on in main stream house building. Great idea, but not worth the millions in research. As has been mentioned almost every pleasure craft has a version lying atop the wheel house

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  • HI we have been doing this for over 10 years in motor homes and caravans What we do is install larger leisure batteries and feed the DC current in an via a controller feed the 12 volt system of the leisure-side of the vehicle

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  • I am doing a similar system on my house at the moment. But it does not have to cost a lot of money. You can produce a 12Volt system for approx £500. With this system you can run all 12V Led lighting in your house; charge all low DC power devices like mobile phones, mp3 players etc and with a small inverter charge or run small ac devices.

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