DC microgrids - from the people who brought you the USBCell

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JennyB   1 kW

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DC microgrids - from the people who brought you the USBCell

Post by JennyB » Dec 14 2010 10:52am

Image

This seems like a good idea - use a single transformer and battery for all your low voltage DC loads and get rid of all the wall warts. :)
http://www.moixaenergy.com/page.asp?pageid=29

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Jeremy Harris   10 GW

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Re: DC microgrids - from the people who brought you the USBC

Post by Jeremy Harris » Dec 14 2010 11:05am

This is a seriously good idea, but if you do the sums then most people will need far, far more solar panels than they show, just to power the everyday DC devices they have around.

I've been thinking of doing something similar, putting a low voltage DC supply around the house to power things like routers, the cable modem etc, and the LED lighting I've already installed in the workshop. I happen to have 200W of solar panels on the boat, that just sit on the drive doing nothing 99% of the time, so I would very much like to get hold of some cheap batteries and give it a go.

The off putting thing is the need to re-wire part of the house to put the low voltage system in, plus the fact that even my big 200W array probably wouldn't be enough to run the wireless router and cable modem all the time, let alone anything else. In practice, a 200W array here in the South of England delivers around 120 watts peak, maybe 50 to 60 watts average, for an average of less than half of any 24 hour period, so maybe 25 watts around the clock, maximum, probably less during the winter.

Jeremy
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vanilla ice   100 MW

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Re: DC microgrids - from the people who brought you the USBC

Post by vanilla ice » Dec 14 2010 12:08pm

Not only the PITA wiring, but isn't voltage drop a problem also? If you have a BIG house, which many people do. How efficient are modern switching wall warts? The worth of wiring DC depends a lot on this too. I've thought about DC wiring, it makes sense for some situations. Not your typical ones, but certain ones.

That PV sun shade for the window looks pretty sweet btw!

picasso   10 mW

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Re: DC microgrids - from the people who brought you the USBC

Post by picasso » Dec 16 2010 11:41am

I think its a good idea. I feel a huge number of people will be installing micro-grids over the next few years. Not just the above type of devices but going full stand alone solar or micro nat gas turbines.

busted_bike   100 mW

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Re: DC microgrids - from the people who brought you the USBC

Post by busted_bike » Dec 16 2010 12:09pm

How does it deal with the fact that my laptop wants 19.5V, my router wants 12V, and my cell phone wants 5V?

Goodness knows what else I have laying around that wants 18V / 24V / 48V...

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vanilla ice   100 MW

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Re: DC microgrids - from the people who brought you the USBC

Post by vanilla ice » Dec 16 2010 1:48pm

You would have to use the little DC/DC converters for that. Which are probably more efficient than the big step down AC/DC ones. If a microgrid standard arises though, the accessory makers would build everything to suit I'd think. 12? Car makers are talking about going higher because 12 is too limiting.. 24?

Just like with the ebikes, if you want to power something high power, its more difficult to do it with lower volts. You will end up with huge currents which presents issues that don't exist with high volts low amps. But I guess its not really going to be a problem if its only used for low power.

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Gordo   100 kW

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Re: DC microgrids - from the people who brought you the USBC

Post by Gordo » Dec 16 2010 2:08pm

Jeremy Harris wrote:This is a seriously good idea, but if you do the sums then most people will need far, far more solar panels than they show, just to power the everyday DC devices they have around.

I've been thinking of doing something similar, putting a low voltage DC supply around the house to power things like routers, the cable modem etc, and the LED lighting I've already installed in the workshop. I happen to have 200W of solar panels on the boat, that just sit on the drive doing nothing 99% of the time, so I would very much like to get hold of some cheap batteries and give it a go.

The off putting thing is the need to re-wire part of the house to put the low voltage system in, plus the fact that even my big 200W array probably wouldn't be enough to run the wireless router and cable modem all the time, let alone anything else. In practice, a 200W array here in the South of England delivers around 120 watts peak, maybe 50 to 60 watts average, for an average of less than half of any 24 hour period, so maybe 25 watts around the clock, maximum, probably less during the winter.

Jeremy
Jeremy;
You know only too well where I am in the rain and fog. We use @ 4KW a day and solar is out of the question. That leaves us with wind or water. I have a 20's steel pole with 4 yards of concrete on the bottom that I have been looking at for a few months. DW says no way. We have a little trickle of water for 6 months of the year at the back of the property about 100M away. From my experience so far, a little water over 24hrs will produce far more power than any other source.

The solution to DC sag losses over distance is to have a battery close to the use point. With 20-30M vessels, we put batteries in the wheelhouse for 12-24V applications.

We just received 48 LCD Light bulbs this morning. Wonderful program, cost $5.00 and get a $7.00 rebate. Save power and a free lunch.
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Re: DC microgrids - from the people who brought you the USBC

Post by x88x » Dec 16 2010 3:28pm

I could see this definitely being a good idea for power stations of a sort, but as has been mentioned, running DC over long cables in the walls presents an efficiency problem...one of the main reasons we don't have DC running to our houses. Instead, how about just the base station without the wall wiring, so anywhere you have a high concentration of DC-powered things, they all share a single high-power AC/DC converter.
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