22 ms·

Slow Electricity: The Return of DC Power? (2016)

86 points by lispython 5y ago

prawn 5y ago
What might realistically happen for this to be achievable in an existing or new home? Or as a default for new homes? I camp a bit and spend more than enough time dealing with 12V lighting, recharging drone batteries from car/aux batteries, etc. Always end up wondering how much of my house actually needs AC, where in the house that occurs (fridge, ducted heating/cooling unit?) and what could get by without it. More and more of my power tools are battery based too. Would AC to the kitchen and garage be enough?
- da_big_ghey 5y ago
  Motors, compressors still are more efficient on AC, for place like American South where air conditioning represent largest segment from electricity expense AC grid remains making sense.
  - stephen_g 5y ago
    Yes, but the very most efficient AC motors and compressors motors use variable frequency drives, and you can design a VFD powered by either AC or DC. I still do think AC is still advantageous in a lot of ways for power grids though, just not on that particular point.
monitron 5y ago
We're currently in the process of designing a house that we hope to build early next year. One thing that I dream of doing is lighting the entire house with LEDs wired in a low voltage DC "network." Even better if they're addressable, dimmable, even RGB recolorable. Power over Ethernet would be a pretty cool way of doing it if it was practical...that way you get the data to control the lights as well as the power to run them. Does anything like this exist in a way that won't get me fired by the builder for even mentioning it?
- lazide 5y ago
  Low voltage electrical is entirely doable and no issues code wise. If you have them run low voltage conduit to wherever you want, you should be good to go. Just be aware many jurisdictions have minimum lighting requirements that your low voltage lights may not meet, but you could always just leave those lights off
- wyager 5y ago
  Low voltage residential wiring is not very efficient for most applications because the conductors have to be so much larger.
  - dreamcompiler 5y ago
    That's true for incandescent lights. It's not true for LEDs because they need ~10x less power.
- asddubs 5y ago
  low voltage is just not a good way to send high amounts of current over even moderately long distances, because low voltage means higher current, which means higher losses to resistance in your wiring, which means you will need much much thicker wiring.
- danielsju6 5y ago
  Ubiquiti has POE panel LEDs https://unifi-led.ui.com/ https://unifi-led.ui.com/ Obviously geared towards offices. I’m sure there are other options. I’m also looking at whole house USB-PD, https://voltekinc.com/dc-power-advantage/ https://voltekinc.com/dc-power-advantage/
- pomian 5y ago
  Look into country cabins, boats and campers. Especially the first though. Many are built with only solar for power. They have 12 volt wiring for 12v lights, and 12v outlets. The only AC is if someone plugs in an inverter to a 12v outlet. If course there are many builds with a main inverter next to the ' battery shack', and often 110 AC wiring from that. But there is a lot of information about pure 12v systems, and it is very doable. The problem is if you are not doing it yourself and are in a city, to find a contractor. If you do a dual setup - I suggest using a different colour of wiring, for the 12v system. ;)
wyager 5y ago
This doesn’t make any sense. Power transmission with DC still requires high voltage for any reasonable efficiency. Then you have to convert it back down to a residential voltage (still probably >100V for conductor material efficiency) and then devices have to convert that down to low voltage. So you’re not actually saving any conversion steps. On top of that, you have to use DC-DC power electronics, which are much more expensive than transformers etc. at high power levels. There is an argument for using DC over AC but avoiding conversion losses is not a compelling part of it.
- bob1029 5y ago
  > On top of that, you have to use DC-DC power electronics, which are much more expensive than transformers etc. at high power levels. Is this actually true though? I just bought a reel of 30 high power mosfets from digikey for ~$450. Each of these bad boys can rock ~1kW continuous switched output/input. Magnetics for the HV boost section of a 30KW DC-DC converter circuit are a mild additional cost. Compare this to how much money you would have to spend for a more traditional copper & iron monstrosity of similar rating (well over $1000). Weight is also a huge factor when you start talking about megawatts.
baybal2 5y ago
Almost every type of DC-DC conversion requires some intermediate AC conversion anyway. And surprise, a lot of DC-DC topologies require a transformer too. Transformers still soundly beat solid state conversion on cost, and efficiency at above the wall outlet voltages. You can't run away from that entirely. If you were to give a free hand to a good EE to redesign the electric grid from scratch, I doubt the result will differ much from what the world has already.
- dreamcompiler 5y ago
  But that intermediate AC is square (not sinusoidal) which means the transistors spend almost no time in the linear range, which means they generate very little heat. And the frequency is much higher than 60Hz too. It's a very different kind of AC, with much more controllable and more efficient electronics. Transformers still have their place but they're still basically big dumb (uncontrollable) chunks of copper and iron.
  - bob1029 5y ago
    > which means they generate very little heat This is incredibly important to note. Buck-boost converters enjoy efficiencies beyond 90% in even the most pedestrian implementations. This makes their efficiency directly competitive with transformer-based designs (95-99%).
chriscjcj 5y ago
Meanwhile, we can't even manage to phase out the penny. Sorry to be so pessimistic on my first post, but I don't see this happening for a long, long time.
__MatrixMan__ 5y ago
If it means less time spent in a mess of wires trying to figure out which adapter brick is squealing, I'm all for it.
- dheera 5y ago
  But please, please, PLEASE design a better connector than fragile USB-C. 120VAC plugs e.g. standard IEC computer power plugs can be hit with bricks and rammed into furniture while they are plugged in and they won't get damaged. All forces of impact get transferred to the chassis, not the PCB. That's good design. I break about a USB-C cable a week because they just aren't designed for the ruggedness that consumer use cases demand, which are typically higher than military.
  - yoz-y 5y ago
    > I break about a USB-C cable a week I don’t know… that seems excessive, even people I’ve known to handle all of their stuff like it’s free have managed to go mostly through 1-2 cables a year.
    - dheera 5y ago
      I mean, the people who design this stuff don't do any user research, they sit in offices and think everyone else sits in offices. Reality is if you go out at all you've probably figured out that phones only come with 1/2 day of real battery life (because they do the damn factory tests with full bars of reception, not real world 1-bar reception), and you needed to charge a phone stuffed in one pocket with a battery in the other pocket, connected by a USB-C cable, and bike, ski, run, hike, climb rocks, whatever it is. Or had to use a laptop in a bus where an asshole plops their heavy ass next to you and you accidentally ram your laptop and USB-C connector into the side wall. Or because pants are designed with only 2 instead of 3 front pockets, one is occupied by wallet and another by a big fat keyring, you have no cohice but to put phone in your back pocket and battery in the other back pocket with a wire between the two and sit on it while plugged in. Or had to stuff your charging phone and battery into a jacket, crumple the whole thing and stuff it into a TSA bin. Or children bite your cables. Or dogs. Or the phone was in the car with a suction cup holder and fell off ramming its USB-C cable into some hard part of the car floor. THIS is daily consumer life. If one hasn't experienced the above, they probably sit in an office all day and work out in a gym and are oblivious to the realities of active lifestyles and how they are highly incompatible with physically weak connectors like USB-C.
Johnny555 5y ago
An LED doesn't run on 24V DC, what's the difference in efficiency between an LED lamp that runs off 120V AC and one that runs off 24V DC?
- axiolite 5y ago
  > An LED doesn't run on 24V DC It can. Cree's JR5050 24‐V LEDs run on 24V. They have 30V and 36V versions as well.
  - petschge 5y ago
    That is because that package internally steps down that voltage. Any LED that produces light in the visible range will have a bandgap in the 1 to 2 Volt range. Feeding it a higher voltage than that would lead to disastrous current run away. The package that contains the LED and the current limiter and whatever other electronics are in there might of course accept 24V DV, or 110V AC or 230V AC or 17.4V at 4kHz. But the question that your parent comment was asking is: For which of those choices is the conversion most efficient to get to the voltage and current that the LED actually needs in the end.
    - dheera 5y ago
      LEDs are usually current-controlled, not voltage controlled. You might have several LEDs in series and they might very well have a voltage drop across all of them of 24V or even much higher when maintaining an operational amount of current.
      - bluGill 5y ago
        The could, but in general you would prefer to wire them in parallel so that nobody notices when one burns out - it just gets a little dimmer.
      - petschge 5y ago
        I know. But at the maximum rated current the voltage drop across the LED is going to be only marginally higher than the band gap. Definitely not 24 Volts. So the question becomes what do you do with the excess voltage. If you are smart you don't just burn it in a resistor. And at that point the question is exactly what the OP asked: For which input voltage do you minimize total losses.
malchow 5y ago
Solar energy is cheap, as in $0.03/kWhr. (PG&E charges you $0.30/kHWhr.) The best inverters convert solar DC to household AC at 97.6 % efficiency. [1] Adding more solar is a question of adding another panel. The inversion loss is a small price to pay for safe power. [2] DC is probably not coming back as a way to wire houses and buildings. [1] https://www4.enphase.com/sites/default/files/downloads/support/IQ7-IQ7plus-DS-EN-US.pdf https://www4.enphase.com/sites/default/files/downloads/suppo... [2] https://www.businessinsider.com/tesla-solar-panel-fires-become-nightmare-some-homeowners-2019-10 https://www.businessinsider.com/tesla-solar-panel-fires-beco...
- antisthenes 5y ago
  DC might come back as a separate in-tandem network specifically for ceiling LED lighting. It's more convenient to simply plug into a low voltage DC current wiring with a LED fixture than to install a AC-DC converter. It's certainly something I've entertained doing for my own place.
- deleted 5y ago
  [deleted]
- KaiserPro 5y ago
  the thing to really highlight here is that having microinverters on the back of each panel increases overall efficiency when even a single panel is partially covered (either by leaves, poop, or damage) otherwise you chain a bunch of panels together in series and track the max power point there. This means that you don't quite optimise for each panel
gwbas1c 5y ago
If you read to the end... This kind of system only makes sense where there aren't major appliances. (Think RVs, off-grid cottages, and developing countries.) I wonder what would happen if we redesigned the grid today? Would it be AC or DC? If AC, would it be a higher frequency? (Smaller transformers) Is modern DC-DC voltage conversation easier than AC-DC? What voltages would we use?
- bluGill 5y ago
  It would be both AC and DC. Different applications do best for different things. DC for long distance, AC for medium distances, and DC very short distances - exactly what we do today. Probably we would use a higher frequency, but that is the only change worth considering. Transformers are efficient and easy, and the things that need high power tend to want AC anyway (though they are moving to VFD which can use DC). The biggest factor is AC is a lot safer. Switches and branch protection devices (fuses) work best on AC. For low voltage DC we can make them work, but for high voltages we don't - instead we put in the protection on an AC side, then convert that to DC.
fortran77 5y ago
> Last but not least, low-voltage DC grids (up to 24V) are considered safe from shock or fire hazard This is absolutely untrue. You may be safer from shocks, but it's a much _worse_ fire hazard. The currents need to be higher at lower voltages. Higher voltages need less current for the same power, decreasing the fire risk.
nikisweeting 5y ago
There is a line that’s incorrect in the article: > AC won, mainly because of its higher efficiency when transported over long distances. AC is not actually more efficient at long distance transmission, it’s less efficient due to the skin effect. AC is just easier to convert.
- bombcar 5y ago
  Yeah I seem to recall that many extremely high voltage long distance lines are actually DC
  - Robotbeat 5y ago
    Indeed. This is because you get phase differences (due to finite speed of signal in wire, even though it's near c) over those distances. Converting to DC and then back to AC at the destination avoids any concern about phase mismatch.
    - lbriner 5y ago
      It isn't just that. afaik, a much larger issue is related to capacitive and inductive losses of AC. Even on the railways, an adjacent 25KV overhead line can induce a few hundred volts into the adjacent "dead" line, which is why they must be earthed before you can work on them.
  - fuoqi 5y ago
    There are two main reasons for using DC for long distance power lines: 1) The line connects two synchronized grids. It's much easier to convert electricity to DC and back to AC on receiving end, than to synchronize grids or to implement something similar with AC. 2) The line runs under sea water for a significant distance. Due to the conductivity losses DC is more efficient in such contexts that AC.
- dehrmann 5y ago
  Yeah, this is a huge myth I hear repeated all the time. AC won because losses are lower at higher voltage and yes, AC transformers (which are necessitated by high voltages) are easy to make.
Robotbeat 5y ago
So, I used to be "team DC" as well, but after learning up a bit, I realized there are still a lot of advantages to AC in the 21st Century. One reason DC power is more viable nowadays is (as others here have mentioned) the use of DC-DC converters. They internally actually use AC to do the conversion (usually at much higher frequency to save weight and cost on inductive elements). But they're not super cheap (not cheaper than transformers) and they can also be inefficient. But part of my problem with this article is it kind of sandbags the efficiency. We can get pretty high efficiency inverters and rectifiers. >90% is common and 95-98% is feasible (and not uncommon). Low voltage DC (like 12V) requires MUCH thicker cables for the same power, which means a lot more copper (and copper mining). Typical line voltage can be very lightweight. With DC, nothing is really at the same voltage, so you need DC-DC converters all over anyway, so you're not saving anything (although not losing much, either!). Another important thing that really drives some of the advantages is: breakers, relays, and (much less important) current measurements of existing cables. All these are feasible for both DC and AC, but cheaper and easier with AC. AC is self-extinguishing as it crosses zero 120 times a second. That means you can switch a circuit on or off when the applied voltage is very low, meaning you can use cheaper and lighter power electronics. Plus, at a given voltage, there's a safety advantage as arcs will more easily stop with AC. I actually think it's funny to see this in a "low tech" blog. DC ubiquity is something really only practical for significant use (i.e. beyond automotive or RV) with modern 21st century power electronics.
- lovemenot 5y ago
  >> With DC, nothing is really at the same voltage, so you need DC-DC converters all over anyway, This may be the case now, but it's just through historical lack of standardisation, resulting from AC having been the one true standard. It's not inherent to DC. USB PD is attempting to address this issue. It is standardising voltages for DC-powered devices.
  - SilverRed 5y ago
    Even internally there is no standard. You may put 12V in your user facing input and the device then splits that in to 12v, 5v, 3.5v for all the different components which run at different voltages.
dehrmann 5y ago
What I'd love is a standardized DC outlet wired into homes that can power anything from a phone to a desktop computer.
- musingsole 5y ago
  USB-C?
  - dheera 5y ago
    USB-C sucks, I break a USB-C cable a week. They're physically too weak. I've very rarely broken 120VAC plugs or cables. Also you can't exactly have a USB-C PD power strip of 10+ plugs without it costing a fortune because of all the negotiation needed per-port. Now they're onto some GaN bullshit just to make the PD adapters smaller. The standards are a shitshow, there are incredible number of non-compliant USB-C cables. 802.3at PoE is slightly better, you can get 24+ ports for a couple hundred bucks, most cables advertised to meet PoE specs do in fact meet them. But really the best would be straight up 48V on 2 rails and a bunch of plugs. No negotiation, no bullshit, no GaN, just 2 wires. Equipment, cabling, power strips would be dirt cheap. Individual devices can have very compact, efficient buck converters to get the voltage they actually need.
    - dreamcompiler 5y ago
      I have a bunch of USB-C PD boards. Each one is about 1x2 cm and costs around $1. That's small enough. And good cables exist.
      - dheera 5y ago
        > Each one is about 1x2 cm and costs around $1. Well, I don't. The 100W PD plugs I own cost typically $60 or more. Put yours on Amazon if they can do 100W and I'll happily buy them. And if it doesn't support full 100W it's a PITA because that's more thing the user has to think about.
    - spockz 5y ago
spoonjim 5y ago
I would love 12VDC wired around my house with step down converters for each room. It would allow Our kids to plug in and unplug most of their things themselves (music players, lights, etc).
- dheera 5y ago
  I'd go for 48VDC. 12V would need some fat wiring to avoid incurring voltage drops for normal amounts of loads. 48V is nice because you can use much thinner wiring, and it's about the highest "safe" voltage to accidentally touch with normal dry skin.
  - spoonjim 5y ago
    48V would definitely be a big ouch or worse for a kid sticking a wet finger inside or something. 12V is completely safe in all circumstances.
    - liotier 5y ago
      Telco employee here... Colleague swapping a card touched 48V - knocked out for a little while, came back and was taken to the hospital for check-up and recovery. 48V at typical rack amperages is no joke.
Animats 5y ago
"Early DC power stations had a dynamo for every light bulb. Source unknown." I have no idea where they got that picture either. Edison's Pearl St. station did not work that way, and that was the first power station. The generator shown is Edison's famous "long-waisted Mary Ann". But Edison never built a one generator per bulb power station. He was able to calculate ROI [1]. This is probably some conceptual drawing of what would have been necessary had the "subdivision of the electric light" (a hot issue around 1889)[2] had not been accomplished. "In other words, a DC electrical system could make a solar PV system more energy efficient." Not clear that it matters much in terms of raw conversion efficiency. Solar inverters are now up around 96-98% efficiency. If you're going to have batteries, you need something that handles battery charging, discharging, and some constant output, and while you can get all that stuff for 12VDC or 24VDC, it's not any more efficient than outputting 120VAC. The real argument they're making is to save power by using small boat or RV sized appliances. They're available, efficient, undersized, and about 3x as expensive as line-powered units.[3] [1] https://www.hup.harvard.edu/catalog.php?isbn=9780674423640 https://www.hup.harvard.edu/catalog.php?isbn=9780674423640 [2] https://www.nature.com/articles/040152a0.pdf https://www.nature.com/articles/040152a0.pdf [3] https://www.thecabindepot.com/collections/appliances https://www.thecabindepot.com/collections/appliances
IlliOnato 5y ago
I read the whole article with sympathetic interest, until the conclusion: > One way to solve the problem of high power devices is simply not to use them -- this is the approach that's followed in sailboats, motorhomes and caravans > Obviously, this strategy implies a change in our way of life. It would mean that electricity is used only for lighting, electronics and refrigeration, while non-electric alternatives are chosen for all other appliances. Not coincidentally, this is quite similar to how DC grids were operated in the late nineteenth century, when the only electric load was for lighting -- first arc lamps and later incandescent bulbs. > Thus, no dishwasher, but doing the dishes by hand. No washing machine, but doing the laundry in a laundromat or with a manually operated machine. No tumble dryer, but a clothes line. No convenient and time-saving kitchen appliances like electric kettles, microwaves and coffee machines, but a traditional cooking stove operated by (bio)gas, a solar cooker, or a rocket stove. No vacuum cleaner, but a broom and a carpet-beater. No freezer, but fresh ingredients. No electric warm water boiler, but a solar boiler and a small wash at the sink if the sun doesn't shine. No electric car, but a bicycle.
- function_seven 5y ago
  I get unreasonably angry when Victorian cosplayers think they've found the solution to our wasteful modern life. Simply eschew modern conveniences and spend hours each week beating your clothes against a rock! Simple, instead of grocery shopping twice a month, ditch that wasteful freezer and walk to the farmers' market down the block before dinner each night. Was it cloudy yesterday? Simple!, take a whore-bath¹ at the sink and be thankful your meetings are on Zoom these days :) Ok, ok, those are caricatures of the final paragraphs, but that's what I hear when the word "simple" is abused that way. [¹] Or, "PTA", which isn't much nicer. Any ideas on what to call this that's less vulgar, but still derisive?
  - tootie 5y ago
    It's frequently much more energy intensive too. Cars are a lot more efficient than horses and dishwashers are more efficient than hand washing.
CyberRabbi 5y ago
Seems like distributing power at low voltages, whether DC or AC will result in lower efficiency so it seems like using low voltage DC for higher efficiency distribution is a bit of a wash. It’s likely AC conversion efficiency will increase over time anyway.
skybrian 5y ago
I'm not sure I care whether it's AC or DC, but it might be nice to have some parallel off-the-grid wiring that comes from a solar-charged battery and will run during a power outage. What would work best for this?
- Karrot_Kream 5y ago
  This gets complicated and depending on your local regulations, may involve an electrician to certify the work. It's similar to the wiring that goes into adding a generator to your home. If you want something a bit less sophisticated but works nonetheless, you can try to wire solar cells, charge controller, and other stuff to a battery, and then just use the battery directly to power devices. Maybe even have two batteries, one being charged, and one being used. I've had friends do this setup in places where they've been renting.
- bob1029 5y ago
  I've been looking at stuff in this space and there are a few options on the market (most out of stock at the moment). Check out options like the Yeti 6000x. You can buy a transfer switch to go with it for powering a few circuits. The 6kwh battery could run things like your fridge and computers for at least a day.
- bluGill 5y ago
  Why parallel as opposed to the same wires? There are good answers for this, but for most people what is best second circuit box that runs just the fridge and a few important lights (in my case the well for water). This way you use the same appliances for everything. A parallel circuit implies when the power is out you have to use something different. As I type this my house is running from a backup generator. The power company has their repair crew in route to whatever the issue is. I'm looking into how/if I can add solar to the system as well.
- stephen_g 5y ago
  I’m looking at building a system based on a Victron Multiplus II inverter/charger - first an off-grid system for a friend who has bought a large property with no power line hookup, and then my own system at home. It’ll just hook into my existing wiring. They have an automatic transfer switch built in for anti-islanding (your mains entry goes through it), so it disconnects you from the grid if it goes down but your local side still operates. I think it can also have two AC outputs, one for loads powered by either grid or battery, and one that is only on when the grid is present (if you have a grid). You can use any type of battery so you’re not locked in (LiFePO4 are some of the best at the moment). I have an AC solar inverter and 5kW of panels on my roof, which would be about enough, but I’m going to add another four panels (bit less than 1.5kW) that are DC-coupled through an MPPT charter (Victron SmartSolar MPPT) to solve the bootstrap problem for prolonged outages (which are very rare here, but still). Not sure if that’s the normal term, but I mean where the batteries run out, so without the grid to put some charge in them, the inverter/charger can’t produce an AC waveform for the PV inverter to lock to, so the PV inverter won’t switch on. Having some solar on the DC charger lets that work.
zurn 5y ago
Many of the loads discussed, eg washing machines, are also reasonable matches a local solar power source, as it's much cheaper to buffer hot water than have large batteries. (Water heating dominates the energy used in those, the mechanical sloshing around takes trivial power compared to it).
- lbriner 5y ago
  And what do you do for the 6 months of the year when there is not enough solar to heat water to a suitable temperature?
  - bluGill 5y ago
    Depends on where you live, but generally this is enough solar, you just need enough well insulated storage to last a few weeks.
  - zurn 5y ago
    People living in arctic areas with multi-month polar night generally already have some other heating energy source, as it gets a bit chilly. But in the summer they can have 24/7 solar energy! There's not many people living in these areas though like the sibling comment points out.
awesomeusername 5y ago
To all the detractors here. I lived on a boat for many years which was 12v only and didn't have the mod cons. You adapt pretty quick then hardly think about it. So everyone saying how it's fantasy to expect peoples behaviour to change, just remember if you haven't tried it you are likely highly over estimating how much effort it is, and not aware of many of the unexpected advantages.
- pomian 5y ago
  I agree. We also built and lived on a sea going boat. You learn a lot about infrastructure to make yourselves independent. As early as the late 70's, we had solar connected to a 12v DC system. That allowed us to run lights, radios, navigation equipment, refrigeration or heating, for as long as we were at sea. Sustainable for over 2 -3 years - Battery life was the limit. {Well, obviously food and water at sea were also a limit.) 2021. That system is still running! everything you need is in there.
- skybrian 5y ago
  Sure, the wires won’t be very long in a boat, though?
- hollerith 5y ago
  "mod cons" is probably British for "modern conveniences".
klondike_ 5y ago
DC wiring is already standard in many office buildings in the form of power over Ethernet (PoE). It powers access points, lighting, and infrastructure, and high power variants can do 100W+. Since it's under 50V, the IT guy can install it without a qualified electrician. High power loads like motors and heaters will continue to require AC but I see no reason why small loads can't use PoE. I would love to see it take off for residential use, especially for IoT stuff.
- jwr 5y ago
  PoE is great, but it's really a crutch: a workaround for when you can't run additional wiring. Its main advantage is that you don't have to use additional wiring. The only reason PoE makes sense at all is because it uses 48V, but due to the flimsy cables the losses are still 15-20%. Not great.
- throw0101a 5y ago
  > It powers access points, lighting, and infrastructure, and high power variants can do 100W+. 802.3bt Type 4 allows for sending 100W down Cat 6A cables, but only 71W is available at the other end. That's highly inefficient. * https://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_implementation https://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_i...
  - upofadown 5y ago
    The loss is proportional to the length and ethernet cables are usually much shorter than the maximum length allowed by the standard.
c_o_n_v_e_x 5y ago
The contrast of articles currently on the HN front page is amusing. We have this article that discusses changing home design in order to limit cabling losses (crazy) and not using "high power" appliances that we associate with modern life... and another article discussing Livermore labs achieving net positive fusion, a milestone that seemingly hints we're on the cusp of a carbon free renaissance of power generation. Schrodinger comes to mind
rob_c 5y ago
Well yes, but frankly given the small losses due to modern conversion systems being so efficient I think we're worrying about catching that last small%age if energy losses. As much as I personally hate them, would it not be better to install 120% of solar cells required to match the load upfront. Given the energy is free at generation write off this small inefficiency as being built into the system. It's not like the sun will come after you for capturing more than your fair share. This feels like a problem for 2100 imo once we've moved to much lower carbon supplies.

86 points by lispython 5y ago

What might realistically happen for this to be achievable in an existing or new home? Or as a default for new homes? I camp a bit and spend more than enough time dealing with 12V lighting, recharging drone batteries from car/aux batteries, etc. Always end up wondering how much of my house actually needs AC, where in the house that occurs (fridge, ducted heating/cooling unit?) and what could get by without it. More and more of my power tools are battery based too. Would AC to the kitchen and garage be enough?

da_big_ghey 5y ago
Motors, compressors still are more efficient on AC, for place like American South where air conditioning represent largest segment from electricity expense AC grid remains making sense.
- stephen_g 5y ago
  Yes, but the very most efficient AC motors and compressors motors use variable frequency drives, and you can design a VFD powered by either AC or DC. I still do think AC is still advantageous in a lot of ways for power grids though, just not on that particular point.

monitron 5y ago

We're currently in the process of designing a house that we hope to build early next year. One thing that I dream of doing is lighting the entire house with LEDs wired in a low voltage DC "network." Even better if they're addressable, dimmable, even RGB recolorable. Power over Ethernet would be a pretty cool way of doing it if it was practical...that way you get the data to control the lights as well as the power to run them. Does anything like this exist in a way that won't get me fired by the builder for even mentioning it?

lazide 5y ago
Low voltage electrical is entirely doable and no issues code wise. If you have them run low voltage conduit to wherever you want, you should be good to go. Just be aware many jurisdictions have minimum lighting requirements that your low voltage lights may not meet, but you could always just leave those lights off
wyager 5y ago
Low voltage residential wiring is not very efficient for most applications because the conductors have to be so much larger.
- dreamcompiler 5y ago
  That's true for incandescent lights. It's not true for LEDs because they need ~10x less power.
asddubs 5y ago
low voltage is just not a good way to send high amounts of current over even moderately long distances, because low voltage means higher current, which means higher losses to resistance in your wiring, which means you will need much much thicker wiring.
danielsju6 5y ago
Ubiquiti has POE panel LEDs https://unifi-led.ui.com/ https://unifi-led.ui.com/ Obviously geared towards offices. I’m sure there are other options. I’m also looking at whole house USB-PD, https://voltekinc.com/dc-power-advantage/ https://voltekinc.com/dc-power-advantage/
pomian 5y ago
Look into country cabins, boats and campers. Especially the first though. Many are built with only solar for power. They have 12 volt wiring for 12v lights, and 12v outlets. The only AC is if someone plugs in an inverter to a 12v outlet. If course there are many builds with a main inverter next to the ' battery shack', and often 110 AC wiring from that. But there is a lot of information about pure 12v systems, and it is very doable. The problem is if you are not doing it yourself and are in a city, to find a contractor. If you do a dual setup - I suggest using a different colour of wiring, for the 12v system. ;)

wyager 5y ago

This doesn’t make any sense. Power transmission with DC still requires high voltage for any reasonable efficiency. Then you have to convert it back down to a residential voltage (still probably >100V for conductor material efficiency) and then devices have to convert that down to low voltage. So you’re not actually saving any conversion steps. On top of that, you have to use DC-DC power electronics, which are much more expensive than transformers etc. at high power levels. There is an argument for using DC over AC but avoiding conversion losses is not a compelling part of it.

bob1029 5y ago
> On top of that, you have to use DC-DC power electronics, which are much more expensive than transformers etc. at high power levels. Is this actually true though? I just bought a reel of 30 high power mosfets from digikey for ~$450. Each of these bad boys can rock ~1kW continuous switched output/input. Magnetics for the HV boost section of a 30KW DC-DC converter circuit are a mild additional cost. Compare this to how much money you would have to spend for a more traditional copper & iron monstrosity of similar rating (well over $1000). Weight is also a huge factor when you start talking about megawatts.

baybal2 5y ago

Almost every type of DC-DC conversion requires some intermediate AC conversion anyway. And surprise, a lot of DC-DC topologies require a transformer too. Transformers still soundly beat solid state conversion on cost, and efficiency at above the wall outlet voltages. You can't run away from that entirely. If you were to give a free hand to a good EE to redesign the electric grid from scratch, I doubt the result will differ much from what the world has already.

dreamcompiler 5y ago
But that intermediate AC is square (not sinusoidal) which means the transistors spend almost no time in the linear range, which means they generate very little heat. And the frequency is much higher than 60Hz too. It's a very different kind of AC, with much more controllable and more efficient electronics. Transformers still have their place but they're still basically big dumb (uncontrollable) chunks of copper and iron.
- bob1029 5y ago
  > which means they generate very little heat This is incredibly important to note. Buck-boost converters enjoy efficiencies beyond 90% in even the most pedestrian implementations. This makes their efficiency directly competitive with transformer-based designs (95-99%).

chriscjcj 5y ago

Meanwhile, we can't even manage to phase out the penny. Sorry to be so pessimistic on my first post, but I don't see this happening for a long, long time.

__MatrixMan__ 5y ago

If it means less time spent in a mess of wires trying to figure out which adapter brick is squealing, I'm all for it.

dheera 5y ago
But please, please, PLEASE design a better connector than fragile USB-C. 120VAC plugs e.g. standard IEC computer power plugs can be hit with bricks and rammed into furniture while they are plugged in and they won't get damaged. All forces of impact get transferred to the chassis, not the PCB. That's good design. I break about a USB-C cable a week because they just aren't designed for the ruggedness that consumer use cases demand, which are typically higher than military.
- yoz-y 5y ago
  > I break about a USB-C cable a week I don’t know… that seems excessive, even people I’ve known to handle all of their stuff like it’s free have managed to go mostly through 1-2 cables a year.
  - dheera 5y ago
    I mean, the people who design this stuff don't do any user research, they sit in offices and think everyone else sits in offices. Reality is if you go out at all you've probably figured out that phones only come with 1/2 day of real battery life (because they do the damn factory tests with full bars of reception, not real world 1-bar reception), and you needed to charge a phone stuffed in one pocket with a battery in the other pocket, connected by a USB-C cable, and bike, ski, run, hike, climb rocks, whatever it is. Or had to use a laptop in a bus where an asshole plops their heavy ass next to you and you accidentally ram your laptop and USB-C connector into the side wall. Or because pants are designed with only 2 instead of 3 front pockets, one is occupied by wallet and another by a big fat keyring, you have no cohice but to put phone in your back pocket and battery in the other back pocket with a wire between the two and sit on it while plugged in. Or had to stuff your charging phone and battery into a jacket, crumple the whole thing and stuff it into a TSA bin. Or children bite your cables. Or dogs. Or the phone was in the car with a suction cup holder and fell off ramming its USB-C cable into some hard part of the car floor. THIS is daily consumer life. If one hasn't experienced the above, they probably sit in an office all day and work out in a gym and are oblivious to the realities of active lifestyles and how they are highly incompatible with physically weak connectors like USB-C.

Johnny555 5y ago

An LED doesn't run on 24V DC, what's the difference in efficiency between an LED lamp that runs off 120V AC and one that runs off 24V DC?

axiolite 5y ago
> An LED doesn't run on 24V DC It can. Cree's JR5050 24‐V LEDs run on 24V. They have 30V and 36V versions as well.
- petschge 5y ago
  That is because that package internally steps down that voltage. Any LED that produces light in the visible range will have a bandgap in the 1 to 2 Volt range. Feeding it a higher voltage than that would lead to disastrous current run away. The package that contains the LED and the current limiter and whatever other electronics are in there might of course accept 24V DV, or 110V AC or 230V AC or 17.4V at 4kHz. But the question that your parent comment was asking is: For which of those choices is the conversion most efficient to get to the voltage and current that the LED actually needs in the end.
  - dheera 5y ago
    LEDs are usually current-controlled, not voltage controlled. You might have several LEDs in series and they might very well have a voltage drop across all of them of 24V or even much higher when maintaining an operational amount of current.
    - bluGill 5y ago
      The could, but in general you would prefer to wire them in parallel so that nobody notices when one burns out - it just gets a little dimmer.
    - petschge 5y ago
      I know. But at the maximum rated current the voltage drop across the LED is going to be only marginally higher than the band gap. Definitely not 24 Volts. So the question becomes what do you do with the excess voltage. If you are smart you don't just burn it in a resistor. And at that point the question is exactly what the OP asked: For which input voltage do you minimize total losses.

malchow 5y ago

Solar energy is cheap, as in $0.03/kWhr. (PG&E charges you $0.30/kHWhr.) The best inverters convert solar DC to household AC at 97.6 % efficiency. [1] Adding more solar is a question of adding another panel. The inversion loss is a small price to pay for safe power. [2] DC is probably not coming back as a way to wire houses and buildings. [1] https://www4.enphase.com/sites/default/files/downloads/support/IQ7-IQ7plus-DS-EN-US.pdf https://www4.enphase.com/sites/default/files/downloads/suppo... [2] https://www.businessinsider.com/tesla-solar-panel-fires-become-nightmare-some-homeowners-2019-10 https://www.businessinsider.com/tesla-solar-panel-fires-beco...

antisthenes 5y ago
DC might come back as a separate in-tandem network specifically for ceiling LED lighting. It's more convenient to simply plug into a low voltage DC current wiring with a LED fixture than to install a AC-DC converter. It's certainly something I've entertained doing for my own place.
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KaiserPro 5y ago
the thing to really highlight here is that having microinverters on the back of each panel increases overall efficiency when even a single panel is partially covered (either by leaves, poop, or damage) otherwise you chain a bunch of panels together in series and track the max power point there. This means that you don't quite optimise for each panel

gwbas1c 5y ago

If you read to the end... This kind of system only makes sense where there aren't major appliances. (Think RVs, off-grid cottages, and developing countries.) I wonder what would happen if we redesigned the grid today? Would it be AC or DC? If AC, would it be a higher frequency? (Smaller transformers) Is modern DC-DC voltage conversation easier than AC-DC? What voltages would we use?

bluGill 5y ago
It would be both AC and DC. Different applications do best for different things. DC for long distance, AC for medium distances, and DC very short distances - exactly what we do today. Probably we would use a higher frequency, but that is the only change worth considering. Transformers are efficient and easy, and the things that need high power tend to want AC anyway (though they are moving to VFD which can use DC). The biggest factor is AC is a lot safer. Switches and branch protection devices (fuses) work best on AC. For low voltage DC we can make them work, but for high voltages we don't - instead we put in the protection on an AC side, then convert that to DC.

fortran77 5y ago

> Last but not least, low-voltage DC grids (up to 24V) are considered safe from shock or fire hazard This is absolutely untrue. You may be safer from shocks, but it's a much _worse_ fire hazard. The currents need to be higher at lower voltages. Higher voltages need less current for the same power, decreasing the fire risk.

nikisweeting 5y ago

There is a line that’s incorrect in the article: > AC won, mainly because of its higher efficiency when transported over long distances. AC is not actually more efficient at long distance transmission, it’s less efficient due to the skin effect. AC is just easier to convert.

bombcar 5y ago
Yeah I seem to recall that many extremely high voltage long distance lines are actually DC
- Robotbeat 5y ago
  Indeed. This is because you get phase differences (due to finite speed of signal in wire, even though it's near c) over those distances. Converting to DC and then back to AC at the destination avoids any concern about phase mismatch.
  - lbriner 5y ago
    It isn't just that. afaik, a much larger issue is related to capacitive and inductive losses of AC. Even on the railways, an adjacent 25KV overhead line can induce a few hundred volts into the adjacent "dead" line, which is why they must be earthed before you can work on them.
- fuoqi 5y ago
  There are two main reasons for using DC for long distance power lines: 1) The line connects two synchronized grids. It's much easier to convert electricity to DC and back to AC on receiving end, than to synchronize grids or to implement something similar with AC. 2) The line runs under sea water for a significant distance. Due to the conductivity losses DC is more efficient in such contexts that AC.
dehrmann 5y ago
Yeah, this is a huge myth I hear repeated all the time. AC won because losses are lower at higher voltage and yes, AC transformers (which are necessitated by high voltages) are easy to make.

Robotbeat 5y ago

So, I used to be "team DC" as well, but after learning up a bit, I realized there are still a lot of advantages to AC in the 21st Century. One reason DC power is more viable nowadays is (as others here have mentioned) the use of DC-DC converters. They internally actually use AC to do the conversion (usually at much higher frequency to save weight and cost on inductive elements). But they're not super cheap (not cheaper than transformers) and they can also be inefficient. But part of my problem with this article is it kind of sandbags the efficiency. We can get pretty high efficiency inverters and rectifiers. >90% is common and 95-98% is feasible (and not uncommon). Low voltage DC (like 12V) requires MUCH thicker cables for the same power, which means a lot more copper (and copper mining). Typical line voltage can be very lightweight. With DC, nothing is really at the same voltage, so you need DC-DC converters all over anyway, so you're not saving anything (although not losing much, either!). Another important thing that really drives some of the advantages is: breakers, relays, and (much less important) current measurements of existing cables. All these are feasible for both DC and AC, but cheaper and easier with AC. AC is self-extinguishing as it crosses zero 120 times a second. That means you can switch a circuit on or off when the applied voltage is very low, meaning you can use cheaper and lighter power electronics. Plus, at a given voltage, there's a safety advantage as arcs will more easily stop with AC. I actually think it's funny to see this in a "low tech" blog. DC ubiquity is something really only practical for significant use (i.e. beyond automotive or RV) with modern 21st century power electronics.

lovemenot 5y ago
>> With DC, nothing is really at the same voltage, so you need DC-DC converters all over anyway, This may be the case now, but it's just through historical lack of standardisation, resulting from AC having been the one true standard. It's not inherent to DC. USB PD is attempting to address this issue. It is standardising voltages for DC-powered devices.
- SilverRed 5y ago
  Even internally there is no standard. You may put 12V in your user facing input and the device then splits that in to 12v, 5v, 3.5v for all the different components which run at different voltages.

dehrmann 5y ago

What I'd love is a standardized DC outlet wired into homes that can power anything from a phone to a desktop computer.

musingsole 5y ago
USB-C?
- dheera 5y ago
  USB-C sucks, I break a USB-C cable a week. They're physically too weak. I've very rarely broken 120VAC plugs or cables. Also you can't exactly have a USB-C PD power strip of 10+ plugs without it costing a fortune because of all the negotiation needed per-port. Now they're onto some GaN bullshit just to make the PD adapters smaller. The standards are a shitshow, there are incredible number of non-compliant USB-C cables. 802.3at PoE is slightly better, you can get 24+ ports for a couple hundred bucks, most cables advertised to meet PoE specs do in fact meet them. But really the best would be straight up 48V on 2 rails and a bunch of plugs. No negotiation, no bullshit, no GaN, just 2 wires. Equipment, cabling, power strips would be dirt cheap. Individual devices can have very compact, efficient buck converters to get the voltage they actually need.
  - dreamcompiler 5y ago
    I have a bunch of USB-C PD boards. Each one is about 1x2 cm and costs around $1. That's small enough. And good cables exist.
    - dheera 5y ago
      > Each one is about 1x2 cm and costs around $1. Well, I don't. The 100W PD plugs I own cost typically $60 or more. Put yours on Amazon if they can do 100W and I'll happily buy them. And if it doesn't support full 100W it's a PITA because that's more thing the user has to think about.
  - spockz 5y ago

spoonjim 5y ago

I would love 12VDC wired around my house with step down converters for each room. It would allow Our kids to plug in and unplug most of their things themselves (music players, lights, etc).

dheera 5y ago
I'd go for 48VDC. 12V would need some fat wiring to avoid incurring voltage drops for normal amounts of loads. 48V is nice because you can use much thinner wiring, and it's about the highest "safe" voltage to accidentally touch with normal dry skin.
- spoonjim 5y ago
  48V would definitely be a big ouch or worse for a kid sticking a wet finger inside or something. 12V is completely safe in all circumstances.
  - liotier 5y ago
    Telco employee here... Colleague swapping a card touched 48V - knocked out for a little while, came back and was taken to the hospital for check-up and recovery. 48V at typical rack amperages is no joke.

Animats 5y ago

"Early DC power stations had a dynamo for every light bulb. Source unknown." I have no idea where they got that picture either. Edison's Pearl St. station did not work that way, and that was the first power station. The generator shown is Edison's famous "long-waisted Mary Ann". But Edison never built a one generator per bulb power station. He was able to calculate ROI [1]. This is probably some conceptual drawing of what would have been necessary had the "subdivision of the electric light" (a hot issue around 1889)[2] had not been accomplished. "In other words, a DC electrical system could make a solar PV system more energy efficient." Not clear that it matters much in terms of raw conversion efficiency. Solar inverters are now up around 96-98% efficiency. If you're going to have batteries, you need something that handles battery charging, discharging, and some constant output, and while you can get all that stuff for 12VDC or 24VDC, it's not any more efficient than outputting 120VAC. The real argument they're making is to save power by using small boat or RV sized appliances. They're available, efficient, undersized, and about 3x as expensive as line-powered units.[3] [1] https://www.hup.harvard.edu/catalog.php?isbn=9780674423640 https://www.hup.harvard.edu/catalog.php?isbn=9780674423640 [2] https://www.nature.com/articles/040152a0.pdf https://www.nature.com/articles/040152a0.pdf [3] https://www.thecabindepot.com/collections/appliances https://www.thecabindepot.com/collections/appliances

IlliOnato 5y ago

I read the whole article with sympathetic interest, until the conclusion: > One way to solve the problem of high power devices is simply not to use them -- this is the approach that's followed in sailboats, motorhomes and caravans > Obviously, this strategy implies a change in our way of life. It would mean that electricity is used only for lighting, electronics and refrigeration, while non-electric alternatives are chosen for all other appliances. Not coincidentally, this is quite similar to how DC grids were operated in the late nineteenth century, when the only electric load was for lighting -- first arc lamps and later incandescent bulbs. > Thus, no dishwasher, but doing the dishes by hand. No washing machine, but doing the laundry in a laundromat or with a manually operated machine. No tumble dryer, but a clothes line. No convenient and time-saving kitchen appliances like electric kettles, microwaves and coffee machines, but a traditional cooking stove operated by (bio)gas, a solar cooker, or a rocket stove. No vacuum cleaner, but a broom and a carpet-beater. No freezer, but fresh ingredients. No electric warm water boiler, but a solar boiler and a small wash at the sink if the sun doesn't shine. No electric car, but a bicycle.

function_seven 5y ago
I get unreasonably angry when Victorian cosplayers think they've found the solution to our wasteful modern life. Simply eschew modern conveniences and spend hours each week beating your clothes against a rock! Simple, instead of grocery shopping twice a month, ditch that wasteful freezer and walk to the farmers' market down the block before dinner each night. Was it cloudy yesterday? Simple!, take a whore-bath¹ at the sink and be thankful your meetings are on Zoom these days :) Ok, ok, those are caricatures of the final paragraphs, but that's what I hear when the word "simple" is abused that way. [¹] Or, "PTA", which isn't much nicer. Any ideas on what to call this that's less vulgar, but still derisive?
- tootie 5y ago
  It's frequently much more energy intensive too. Cars are a lot more efficient than horses and dishwashers are more efficient than hand washing.

CyberRabbi 5y ago

Seems like distributing power at low voltages, whether DC or AC will result in lower efficiency so it seems like using low voltage DC for higher efficiency distribution is a bit of a wash. It’s likely AC conversion efficiency will increase over time anyway.

skybrian 5y ago

I'm not sure I care whether it's AC or DC, but it might be nice to have some parallel off-the-grid wiring that comes from a solar-charged battery and will run during a power outage. What would work best for this?

Karrot_Kream 5y ago
This gets complicated and depending on your local regulations, may involve an electrician to certify the work. It's similar to the wiring that goes into adding a generator to your home. If you want something a bit less sophisticated but works nonetheless, you can try to wire solar cells, charge controller, and other stuff to a battery, and then just use the battery directly to power devices. Maybe even have two batteries, one being charged, and one being used. I've had friends do this setup in places where they've been renting.
bob1029 5y ago
I've been looking at stuff in this space and there are a few options on the market (most out of stock at the moment). Check out options like the Yeti 6000x. You can buy a transfer switch to go with it for powering a few circuits. The 6kwh battery could run things like your fridge and computers for at least a day.
bluGill 5y ago
Why parallel as opposed to the same wires? There are good answers for this, but for most people what is best second circuit box that runs just the fridge and a few important lights (in my case the well for water). This way you use the same appliances for everything. A parallel circuit implies when the power is out you have to use something different. As I type this my house is running from a backup generator. The power company has their repair crew in route to whatever the issue is. I'm looking into how/if I can add solar to the system as well.
stephen_g 5y ago
I’m looking at building a system based on a Victron Multiplus II inverter/charger - first an off-grid system for a friend who has bought a large property with no power line hookup, and then my own system at home. It’ll just hook into my existing wiring. They have an automatic transfer switch built in for anti-islanding (your mains entry goes through it), so it disconnects you from the grid if it goes down but your local side still operates. I think it can also have two AC outputs, one for loads powered by either grid or battery, and one that is only on when the grid is present (if you have a grid). You can use any type of battery so you’re not locked in (LiFePO4 are some of the best at the moment). I have an AC solar inverter and 5kW of panels on my roof, which would be about enough, but I’m going to add another four panels (bit less than 1.5kW) that are DC-coupled through an MPPT charter (Victron SmartSolar MPPT) to solve the bootstrap problem for prolonged outages (which are very rare here, but still). Not sure if that’s the normal term, but I mean where the batteries run out, so without the grid to put some charge in them, the inverter/charger can’t produce an AC waveform for the PV inverter to lock to, so the PV inverter won’t switch on. Having some solar on the DC charger lets that work.

zurn 5y ago

Many of the loads discussed, eg washing machines, are also reasonable matches a local solar power source, as it's much cheaper to buffer hot water than have large batteries. (Water heating dominates the energy used in those, the mechanical sloshing around takes trivial power compared to it).

lbriner 5y ago
And what do you do for the 6 months of the year when there is not enough solar to heat water to a suitable temperature?
- bluGill 5y ago
  Depends on where you live, but generally this is enough solar, you just need enough well insulated storage to last a few weeks.
- zurn 5y ago
  People living in arctic areas with multi-month polar night generally already have some other heating energy source, as it gets a bit chilly. But in the summer they can have 24/7 solar energy! There's not many people living in these areas though like the sibling comment points out.

awesomeusername 5y ago

To all the detractors here. I lived on a boat for many years which was 12v only and didn't have the mod cons. You adapt pretty quick then hardly think about it. So everyone saying how it's fantasy to expect peoples behaviour to change, just remember if you haven't tried it you are likely highly over estimating how much effort it is, and not aware of many of the unexpected advantages.

pomian 5y ago
I agree. We also built and lived on a sea going boat. You learn a lot about infrastructure to make yourselves independent. As early as the late 70's, we had solar connected to a 12v DC system. That allowed us to run lights, radios, navigation equipment, refrigeration or heating, for as long as we were at sea. Sustainable for over 2 -3 years - Battery life was the limit. {Well, obviously food and water at sea were also a limit.) 2021. That system is still running! everything you need is in there.
skybrian 5y ago
Sure, the wires won’t be very long in a boat, though?
hollerith 5y ago
"mod cons" is probably British for "modern conveniences".

klondike_ 5y ago

DC wiring is already standard in many office buildings in the form of power over Ethernet (PoE). It powers access points, lighting, and infrastructure, and high power variants can do 100W+. Since it's under 50V, the IT guy can install it without a qualified electrician. High power loads like motors and heaters will continue to require AC but I see no reason why small loads can't use PoE. I would love to see it take off for residential use, especially for IoT stuff.

jwr 5y ago
PoE is great, but it's really a crutch: a workaround for when you can't run additional wiring. Its main advantage is that you don't have to use additional wiring. The only reason PoE makes sense at all is because it uses 48V, but due to the flimsy cables the losses are still 15-20%. Not great.
throw0101a 5y ago
> It powers access points, lighting, and infrastructure, and high power variants can do 100W+. 802.3bt Type 4 allows for sending 100W down Cat 6A cables, but only 71W is available at the other end. That's highly inefficient. * https://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_implementation https://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_i...
- upofadown 5y ago
  The loss is proportional to the length and ethernet cables are usually much shorter than the maximum length allowed by the standard.

c_o_n_v_e_x 5y ago

The contrast of articles currently on the HN front page is amusing. We have this article that discusses changing home design in order to limit cabling losses (crazy) and not using "high power" appliances that we associate with modern life... and another article discussing Livermore labs achieving net positive fusion, a milestone that seemingly hints we're on the cusp of a carbon free renaissance of power generation. Schrodinger comes to mind

rob_c 5y ago

Well yes, but frankly given the small losses due to modern conversion systems being so efficient I think we're worrying about catching that last small%age if energy losses. As much as I personally hate them, would it not be better to install 120% of solar cells required to match the load upfront. Given the energy is free at generation write off this small inefficiency as being built into the system. It's not like the sun will come after you for capturing more than your fair share. This feels like a problem for 2100 imo once we've moved to much lower carbon supplies.