Yeah, I posted it to the wrong sub.
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Even 95% is on the low side. Most residential-grade PV grid-tie inverters are listed as something like 97.5%. Higher voltage versions tend to do better.
Yeah, filters essentially store power during one part of the cycle and release it during another. Net power lost is fairly minimal, though not zero. DC needs filtering too: all those switchmode power supplies are very choppy.
NZ's Parliament was regularly described as "more Westminster than Westminster" until we moved to MMP in the 90s.
It has its bugs but it's far better than FPP and many alternatives.
You can't really have effective copy protection on any disc that can be played in a basic CD player; they're just too simple.
So Sony's approach was to put an autorun installer for a 'music player' on the disk too. If installed, it attempted to lock your CD drive from being used by any other software and couldn't be easily uninstalled. And they pirated open-source software (yes, that's possible) to build it.
SMH My Head.
Try the Sony BMG Rootkit, contained on music CDs:
In 2005 it was revealed that the implementation of copy protection measures on about 22 million CDs distributed by Sony BMG installed one of two pieces of software that provided a form of digital rights management (DRM) by modifying the operating system to interfere with CD copying. Neither program could easily be uninstalled, and they created vulnerabilities that were exploited by unrelated malware. One of the programs would install and "phone home" with reports on the user's private listening habits, even if the user refused its end-user license agreement (EULA), while the other was not mentioned in the EULA at all. Both programs contained code from several pieces of copylefted free software in an apparent infringement of copyright, and configured the operating system to hide the software's existence, leading to both programs being classified as rootkits.
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Well, that's certainly the answer.
I wouldn't have thought you'd want to put a building quite that close to the waterfront even in a Fjord, but apparently they did.
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I don't think the US/Canada usually does that style of power pole, with three phases on a crossarm and no neutral below.
Barriers on what looks like a pretty low-traffic low-risk road too.
I would think somewhere Scandinavia or central Europe. NZ wouldn't put barriers like that up.
Rock wall near bottom of picture screams old.
I'm not sure there are any power grids past the tens-of-megawatt range that aren't just a 2/3/4 terminal HVDC link.
Railway DC supplies usually just have fat rectifiers and transformers from the AC mains to supply fault current/clearing and stability.
Ships are where I would expect to start seeing them arrive, or aircraft.
Almost all land-based standalone DC networks (again, not few-terminal HVDC links) are heavily battery backed and run at battery voltage - that's not practical once you leave one property.
I'm sure there are some pretty detailed reports and simulations, though. A reduction in cost of multi-kV converters and DC circuit breakers is essential.
PV inverters often have around 1-2% losses. This is not very significant. You also need to convert the voltage anyway because PV output voltage varies with light level.
Buck/boost converters work by converting the DC current to (messy) AC, then back to DC. If you want an isolating converter (necessary for most applications for safety reasons) that converter needs to handle the full power. If it's non isolating, then it's proportional to the voltage step.
Frequency provides a somewhat convenient method for all parties to know whether the grid is over- or under- supplied on a sub-second basis. Operating solely on voltage is more prone to oscillation and requires compensation for voltage drop, plus the information is typically lost at buck/boost sites. A DC grid would likely require much more robust and faster real-time comms.
The AC grid relies on significant (>10x overcurrent) short-term (<5s) overload capability. Inrush and motor starting requires small/short overloads (though still significant). Faults are detected and cleared primarily through the excess current drawn. Fuses/breakers in series will all see the same current from the same fault, but we want only the device closest to the fault to operate to minimise disruption. That's achieved (called discrimination, coordination, or selectivity) by having each device take progressively more time to trip on a fault of a given size, and progressively higher fault current so that the devices upstream still rapidly detect a fault.
RCDs/GFCIs don't coordinate well because there isn't enough room between the smallest fault required to be detected and the maximum disconnection time to fit increasingly less sensitive devices.
Generators are perfectly able to provide this extra fault current through short term temperature rise and inertia. Inverters cannot provide 5-fold overcurrent without being significantly oversized. We even install synchronous condensers (a generator without any actual energy source) in areas far from actual generators to provide local inertia.
AC arcs inherently self-extinguish in most cases. DC arcs do not.
This means that breakers and expulsion type fuses have to be significantly, significantly larger and more expensive. It also means more protection is needed against arcs caused by poor connection, cable clashes, and insulation damage.
Solid state breakers alleviate this somewhat, but it's going to take 20+ years to improve cost, size, and power loss to acceptable levels.
I expect that any 'next generation' system is likely to demand a step increase in safety, not merely matching the existing performance. I suspect that's going to require a 100% coverage fibre comms network parallel to the power conductors, and in accessible areas possibly fully screened cable and isolated supply.
EVs and PV arrays get away with DC networks because they're willing to shut down the whole system in the event of a fault. You don't want a whole neighborhood to go dark because your neighbour's cat gnawed on a laptop charger.
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Has it occurred to you that sometimes there's actual evidence backing up the things you ridicule?
You can go measure the acidity of rain in your back yard if you want.
The sunlight in NZ is far, far harsher than if you go a few thousand kilometres towards the equator, where it should be hotter. We have some of the world's highest rates of skin cancer. Are you implying that crisis actors are faking having skin cancer?
Secondhand stuff can be really cheap if you know where to look, but the drawbacks are usually power and noise.
Here in NZ they do a factory reset on your calculator at the start of every exam.