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48v PoE lighting


mmacleod
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On my current house I have 6 x 320 (1920 watt) artsolar panels and a pylontech US3000.

I run all my DC office equipment (computers, monitors, routers, fibre ont and so on) directly from 48v/24v/12v DC from pylontech batteries without an inverter, I use victron orion devices for the 24v/12v step down for the few devices that don't take 48v but most things are on 48v and a lot of it is running from PoE.

I'm busy building a new small house, and want to do similar, at least for the first phase.
I may potentially expand the system on the new house with more panels and inverter(s) to power other less essential parts of the house as a second phase.

As part of phase1 I'm considering adding in lighting as well, as lighting is another part of the house that is actually more suited for DC than AC.
To do this I am considering the possibility of, instead of running electrical cable all over the place for lighting and light switches, instead to run CAT6 ethernet cable for every fixture, and then to inject ~48v PoE on these CAT6 runs and install PoE compatible lights/switches  - this seems to be a growing thing internationally and in commercial buildings especially but I think its going to be the f future in residential as well..

A few benefits this brings in my mind:
1) Less/cheaper cabling (especially in cases where one light should be controlled by multiple switches, no need for complex wiring to accomplish that just one ethernet cable to each device)
2) Lower consumption (PoE LEDs has been shown to be slightly more efficient than AC ones for cable runs 50m or less, most of mine will be much less)
3) Longer lifetime than AC LEDs.
4) Ability to easily add extras like sensors, wireless hotspots or whatever else and ability for smart control, all without polluting the houses wireless space with dozens of wireless devices.
5) Able to run from batteries without the requirement of an inverter - so house can be setup without one and inverter can be added only later for other things if needed.

Some questions:
1) Has anyone done such a system in za? How did it work for you? Any advice?
2) Does our building code handle this in a sane way or am I likely to have issues in terms of that?
3) Other than this UniFi stuff (https://www.senetic.co.za/product/ULED-AT-2) does anyone know of local places selling decent ranges of this?

Edited by mmacleod
Fix small grammar issue
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I'm like a dog with a bone on this subject. It's good to see someone else realizing the advantages of DC minigrids.

I haven't come across PoE as a power reticulation system other than powering the Ethernet device it is connected to. The CAT 5/6 wiring must have limitations about how much power it can deliver.

There's  no DC reticulation equipment that's available because it isn't an established standard.

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12 minutes ago, Richard Mackay said:

The CAT 5/6 wiring must have limitations about how much power it can deliver.

There are obviously limitations. However a happy thing has happened in recent years, the ever improving efficiency of LEDs and the ever increasing power delivery capabilities of various PoE standards have crossed over, such that for reasonable sized lighting the wattage delivered is enough.

Some of the latest PoE standards available approach 90W, older ones around 30W, even 30W is quite ample power for a modern LED fixture.
This does mean that a separate cable probably needs to be run for each fixture instead of daisy chaining, but I don't see this as a bad thing really as ethernet cable is not that expensive.

One final thing worth noting is that these standards assume ethernet cables of up to 100m in length (as this is what ethernet standard allows for as well) - so for shorter runs the wattage capabilities are actually (in theory) a bit greater than what the standard suggests, even if one probably doesn't want to utilise this extra capability.
Screenshot_20200222_212642.png.d1c589e544d6c7dfcdbfa72a409df2a3.png

Edited by mmacleod
Forgot to mention cable length
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On 2020/02/22 at 3:54 PM, mmacleod said:

1) Has anyone done such a system in za? How did it work for you? Any advice?

One forum member installed LEDs on his home security system. He used the 12V that is already available on each PIR, of which you often have one in each room already. It was not for full illumination, rather to get by during load shedding. I cannot remember who this forum member was though.

 

On 2020/02/22 at 3:54 PM, mmacleod said:

2) Does our building code handle this in a sane way or am I likely to have issues in terms of that?

As long as it's not in the same raceway as the AC wiring, and suitably current limited (which I expect would be the case for equipment built to a standard), I can't really see a problem.

 

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On 2020/02/22 at 3:54 PM, mmacleod said:

Some questions:
1) Has anyone done such a system in za? How did it work for you? Any advice?
2) Does our building code handle this in a sane way or am I likely to have issues in terms of that?
3) Other than this UniFi stuff (https://www.senetic.co.za/product/ULED-AT-2) does anyone know of local places selling decent ranges of this?

Instead of dealing with these specific questions I reckon we need to take a step back. This forum deals almost exclusively with AC and the grids that made this available. The alternatives don't compare due to the dominanace of AC grids.

But AC grids are expensive and currently aren't the most efficient way of power reticulation. see: https://www.economist.com/special-report/2017/11/10/africa-might-leapfrog-straight-to-cheap-renewable-electricity-and-minigrids

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1 hour ago, Richard Mackay said:

Instead of dealing with these specific questions I reckon we need to take a step back. This forum deals almost exclusively with AC and the grids that made this available. The alternatives don't compare due to the dominanace of AC grids.

But AC grids are expensive and currently aren't the most efficient way of power reticulation. see: https://www.economist.com/special-report/2017/11/10/africa-might-leapfrog-straight-to-cheap-renewable-electricity-and-minigrids

I disagree because of one specific kind of load: Induction motors. They are ingenuous little devices, don't need brushes or slip rings, which means you can build motors that last decades. You find them in important appliances like your fridge and freezer, but also in vacuum cleaners, older air conditioners, borehole pumps, and so forth.

The downside: They only work with AC.

So when you have loads like these, your options are 1) get DC alternatives, or 2) get an inverter.

It is almost always cheaper in the long run to get an inverter. And if you need to invest in an inverter in any case, then it's cheaper to use that than to rewire the house.

Also, AC switchgear is cheaper.

On an engineering level I fully understand that it is more efficient to run things from DC and avoid the conversion losses, but unless this is a really small home without a nice city-type fridge, I don't see how you can do away with the AC side.

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To add to that perhaps, I grew up with a DC system on the farm. We had 36VDC lights. My mother's sewing machine had a 32V DC motor. It works well enough, but this was in a house designed with separate circuits from the day it was built.

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20 minutes ago, plonkster said:

On an engineering level I fully understand that it is more efficient to run things from DC and avoid the conversion losses, but unless this is a really small home without a nice city-type fridge, I don't see how you can do away with the AC side.

Well depending on your definition of nice, there are these https://www.sustainable.co.za/defy-d190-158l-solar-combi-fridge-freezer.html which are definitely 'city type', but not quite a bosch/siemens/smeg/samsung/LG level of fancy. Still it does look like we might see DC fridges become more 'normal' in our lifetimes.

That aside, there is still the dishwasher, washing machine, and so on - so I don't personally believe DC only is the way to go. I do think there is a strong case for future houses to have a dual system, probably not as strong a case to modify existing houses where its cheaper to just stick with what is there.
The main thing lacking is decent standards, the latest PoE and USB-C standards go some way to solving this, as more things that run on DC anyway (tv/monitor for example) start taking either of these connectors instead of proprietary ones at the end of their power bricks, then over time as this is more widespread we might start to see a stronger case for this.
Already houses have started with USB plugs in the wall, so already we are closer than we have been in the past.
 

17 minutes ago, plonkster said:

To add to that perhaps, I grew up with a DC system on the farm. We had 36VDC lights. My mother's sewing machine had a 32V DC motor. It works well enough, but this was in a house designed with separate circuits from the day it was built.

And this is more what I'm aiming for here, two circuits built into the house from the start, one of them 48v DC over ethernet cables (with a secondary function of also being able to do data communication) and the other 240v AC over regular wiring.
Everything that makes sense to run off DC to run off DC, for the rest grid power which at a later date could still be augmented with an inverter (an inverter that doesn't need to handle quite as much load as it would with a single system).

I'd want to run ethernet over a lot of the house anyway, as I think more people do in new builds these days, so the two systems are already sort of there its just a matter of extending it to even more parts of the house and putting power over it.

Edited by mmacleod
minor edit
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6 minutes ago, SolarNoob said:

Yeah thats the product range I linked in my senetic link (a few other local places also sell it miro a.o)
Basically what I had in mind, but the range is a bit limited, only a single gang switch and only the one light fixture - seems to mostly be aimed at the office place.

The single light fixture I can get over, but the single gang switch is a bit limiting for a residential house. Hoping to find something a bit nicer.

If I give up on the local market and decide to just import the stuff I've found fancier stuff:

https://www.usa.lighting.philips.com/systems/connected-lighting-for-offices (Phillips seems to have an entire range of PoE lighting for offices)
http://applications.nam.lighting.philips.com/blog/index.php/2016/01/26/philips-antumbra-icolor-keypad-much-more-than-your-average-light-switch/ (struggling to get info from phillips though)
https://www.elanhomesystems.com/product/7-button-single-gang-keypad-white-gKP7 (Multigang PoE switch)
https://www.hubbell.com/hubbellcontrolsolutions/en/Products/Lighting-Controls/Lighting-Controls-Sensors/Wallbox-Devices/Low-Voltage-Switch-RJ45-Enabled/p/2659695 (Dual gang PoE switch)

Still digging around to get more info, it seems like there are definitely products for what I want already out there in the wild (especially overseas), but its hard to get info and its unclear for instance whether each of these brands has their own proprietrary software thats needed or whether it would be relatively simple to mix UniFi lights with someone elses switches or phillips lights with UniFi switches or so on...

Hoping to find someone with experience with some of these products.

 

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20 hours ago, plonkster said:

I disagree because of one specific kind of load: Induction motors. They are ingenuous little devices, don't need brushes or slip rings, which means you can build motors that last decades. You find them in important appliances like your fridge and freezer, but also in vacuum cleaners, older air conditioners, borehole pumps, and so forth.

The downside: They only work with AC.

So when you have loads like these, your options are 1) get DC alternatives, or 2) get an inverter.

It is almost always cheaper in the long run to get an inverter. And if you need to invest in an inverter in any case, then it's cheaper to use that than to rewire the house.

I''m not saying that AC power doesn't have its place. Industry lives and dies by AC. My point is that for many applications it need not necessarily be AC power or nothing.

Consider when you get up in the morning and start your day: Probably the first time you actually switch on an AC device is when you get to the kitchen. 

Wiring a house with different wiring reticulation for different electrical power standards might be expensive but that shouldn't stop us acknowledging what the most efficient prospect is. And in different situations different solutions will apply.

Edited by Richard Mackay
grammar!
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