It’s going to depend how micro that microgrid is. We already have farms running an AC transformer on two ends because the cabling needed over even 1km to run even a few hundred watts of borehole pump is not going to work over anything else.
Yep, this is another article where somebody has put 2 and 2 together and made 57.
Poe may be good for my Xmas tree’s microgrid if I use LEDs.
100W max and 100m max, and probably not simultaneously …pfft.
Sometimes a 10% loss is still magnitudes less than the cost of high power dc cabling.
For a decent sized house, DC just doesn’t seem practical unless you are talking about a couple of led lights.
Yeah, I was wondering, briefly, about a MW, Oven, Stove, and kettle on DC cabling when I see the cable size we have to use on our battery banks, and that is a “short” distance to boot.
It depends on the voltage.
This is the geyser element used by Geyserwise. It has 2 elements: one for direct connection to the PV panels and one for 220V.
As can be seen the wiring isn’t any heavier than a regular AC element.
If on 220V, yes. Isn’t most DC micro grids’ design principle to be low voltage?
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That’s definitely true.
Also true but then we are no longer talking about SAFE dc voltage. I’ve cut 220v live cables in my younger days. Don’t want to imagine doing that with dc
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No. They can be any voltage. This is the challenge of DC since there are no standards. It looks like they will follow the LA battery voltages: (5V) 12V, 24V & 48V
Higher voltages are in the unsafe region so the jury is still out on this. (Geyserwise have done their own thing to match PV panel voltages)
I don’t think DC will be developed for the 3rd world only that don’t have national grids. It’s got to have advantages for the developed world as well…
Its probably worth googling a bit more… Many EV’s and Inverter manufacturers are moving to high voltage (HV) - See 2018 article below to start with…
Yeah, and that also means less losses when going DC → AC - basically you can see the same numbers as with a grid-tied PV inverter for battery → AC.
True, and on top of that, many are switching the 12V auxiliary battery to a 48V battery now. Had a conversation with my Spanish colleague this morning (the one who builds a certain blue mobile app we all love), and he has a Tesla model Y now, with a 48V battery.
But on that topic of DC. I think one reason to not underestimate the complexity of a move to DC, is the increased cost in switch gear. The moment you go above about 30V, we’re talking non-trivial amounts of increased cost on overcurrent protection, breakers, switches, etc etc.
I think we are all agreed that you should use the best tool for the job, which for me means that distribution is best done at high voltage AC, and local use is best done at low voltage DC. Even a trivial distance of 10 meters or so, with higher power levels, and DC starts to fall short.
And also, the one thing I always say: Don’t forget about induction motors. They truly are an engineering marvel. No brushes or slip rings or any such nonsense. The rotating part is essentially the secondary of a transformer. These things are insanely reliable, last forever, and is the reason a fridge can last decades without requiring any significant work done to it.
Now ask anyone with a rural DC-setup who had a specially-built DC fridge made up how well that lasted. In fact, when my dad installed his first inverter in 1987, the ability to use a reliable “dorpsyskas” (town fridge) was one of the reasons.
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Hailed as the game changer from Tesla… all wires are now thinner and all component’s need to be converted to 48v. Huge costs savings if you believe Munro and Associates.
Auto component suppliers are going to have to make huge changes.
And then: Toyota admits Tesla Model Y is "truly a work of art" as it rethinks EV strategy
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For me, the argument here is for very low power stuff like lighting. Inherently switchable, runs up to 100m, real potential for power saving and ease of management.
I don’t know what else PoE powered devices would really benefit beyond the obvious existing uses like networking equipment - powering a rPi or similar, maybe a small display.
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I have installed the simplest of 12V dc reticulation in my house. (presently only one light fitting in the kitchen)
I’m not keen on ‘emergency lighting’ which is always inferior to what you normally use, so my rule is to make the 12V lighting the standard…
Has anybody else installed the same??
I know someone who has something similar. I think it was installed during the 2008 loadshedding days.
A 12V battery with a single PV panel which then has 12V running to some rooms (main bed room, home office, dining room) which then powers 12V GU10 lights that’s installed separately to the ‘main’ lights hanging from the celling.
The GU10 lights can then used during loadshedding to still have light in the house.
It all used to be connected to a small charger with a built-in MPPT to charge them up from the grid with the panel being a backup for extended outages, but that was stolen and replaced by an MPPT which takes the grid charge away, so they’ve had some battery issues since then.
As they’re looking at a whole house backup system now they said they’ll either rip the 12V lights out and patch up the ceiling or replace them with 220V along with the rest of the house.
That would probably be MR16 lamps. I had those in my previous house. It’s becoming hard to find them now.
A 12V bus for low power lighting is no problem at all. As long as the wiring is in a separate raceway (you cannot put this in the same conduit as your 230V wiring), it is properly fused, and the switches are rated for the current and voltage (at 12V that is much less of a concern, your typical AC switch will work fine at this low voltage), this can be an excellent solution.
I’ve seen it done often in camping applications (eg caravans), or for small weekend houses on farms.
This was a DIY done by the previous owner, so I’ve got no idea how it’s done exactly (and if it was done properly and/or even included in the CoC), but I do know they have a single two gang light switch with one for the AC light and one of the DC.
In other words, almost certainly not compliant then 
I’ll put money on that CoC isn’t required…
CoC is required for the AC side, and part of that says you may not have signal cabling and other DC stuff in the same raceway… so yes… this will run afoul of the CoC requirements.
If the DC side is in its own raceway, then maybe you could say it is separate and not part of the CoC.
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