While planning on reorganizing my local network I'm once again wondering how difficult it would be to power all these devices directly with DC. Falling down the rabbit hole of nano sized DC grids and plants.
As I take everything down I think I will inventory the energy usage of each device, and maybe setup some power monitoring when I stand it all back up. That'll give me some numbers to chew on as I think about what a DC system may look like.
@rho power over ethernet? or
@amsomniac Where applicable, but the thought is to get rid of all the wall worts, and power directly through the barrel connectors (fused of course). I just look at this mess of little boxes all doing AC to DC conversion hanging off my UPS, and I have to think there is a better way.
What voltage are you planning to have for a DC plant and how are you going to charge it?
@Tayo I've been looking at LiFePO recently. They seem like they'd be a good fit for a stationary application like this, and have been steadily coming down in price. Initially I'll probably just charge from mains, but try to organize things in such a way that it would be simple to swap in (or add) solar later.
My battery plant is currently 24VDC bit I'm wanting to upgrade to 48VDC. That would require a new rectifier(to charge from the mains) and inverters. My batteries are near EOL and I'm thinking about building a power wall with 18650s. I have reservations about having them in the house with fire issues. If we end up moving, I'm starting over and will let the new owner figure it out here. I will do something at our new house.
@Tayo Oh cool! Why are you wanting to move up to a 48V system? I hear you on those 18650's, they make me nervous as well. Although I have been following along with some of the power wall builds that Jehu Garcia has been doing on youtube, and they look pretty slick.
I may have some questions for you as I try to think through this more.
Greater capacity and demand available at 48VDC. All your big inverters run on 48. Someday, the goal is have enough solar generation to power the entire house and sell the extra.
@Tayo To answer the voltage question. I'm initially thinking 24V, but I'm still unsure.
@rho I have the same thoughts every so often. Like, every time I change a lightbulb.
There are three bulbs in a light fixture in my bedroom. So that's three tiiiiny sets of rectifiers, smoothing caps and switchers, all crammed into tiny lightbulb-sized boxes, all of which will fail before any of the actual light-outputting business does.
And my house is FULL of tiny, inefficient power supplies, one for every device that has any kind of chip in it.
@rho I think it's time for there to be one big, overspecced, reliable and efficient 12v DC power supply in a house. We'd save a LOT of energy.
Seems to me that lighting is the killer app for such a setup. It can be fancier, more beautiful, more efficient and more reliable - that'd get people onboard.
@ifixcoinops I agree. There is only a small handful of things that directly use AC in the average household anymore.
I've been looking at some of the solutions that telecoms and small ISPs use, especially on their remote towers. Usually a 12v, 24v, or 48v DC plant with a battery backup. All din rail mounted, and pretty compact. A lot of those products are available for the general public to buy, and I'm seriously considering trying to cobble something small together as an experiment.
@rho I'd be very interested in seeing how that turns out.
I thought about running 5v everywhere, but I'm leery of the voltage drop over long wire runs. Then I thought about 24v everywhere, until I saw an article written Back In The Day by a carmaker who tried using 24v and all their switches and relays wore out super-fast. So I'm figuring 12v is common for a reason. :)
@ifixcoinops @rho large vans and trucks/lorries use 24V as do lots of SCADA control systems and these components last, its possible the car had underspecified components (maybe due to physical size constraints?)
In telecoms +24V DC battery backed supplies are used in smaller street cabinets, and -48V DC in larger ones (the same as the Telephone Exchange)
The 24V relays for DIN rails that the Italians make and are sold by Radiospares are decent (and presumably available in USA), I've used them for a very basic control system that triggers a burglar alarm autodialler if a water flow alarm activates, and they have worked well for a good few years.
There's quite a lot of 24V infrastructure around intended for use in trucks and boats which could be used indoors..
I think that new houses should be wired for 12 volts, with battery backup, and solar panels by default. - Also what we don't have is a nice 12 volt plug that is somewhat foolsafe.
So much of what we use is powered down from 110 volts AC (in the US) to 12 volts DC.
The plus side is that even in the event of a power grid outage, the house would still have lighting and a little bit of juice to get by with.
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