The real numbers:

If you figure out what the "just enough" solar panel count would be for your max power needs during the shortest day of the year in full sunlight at whatever angle(s) you'll be able to manage, you'll need five to seven times that many to make sure that on non-sunny days you're good to go.

This is because solar panels produce between 15% and 20% of rated capacity on non-sunny days. Non-sunny days are not "dark", they are only "dim." It is a very rare day indeed where it is so dark as to drive a solar panel below 15% output (major snowstorm which has the atmosphere nearly opaque, that kind of thing.) But dim days can come in very long strings, so that's the target to aim at.

For a reliable system that will never let you down, you do tend to need considerably more space than you would initially think. But it is possible, given that you have the space (lots) and the budget (also lots) required. Panel-wise, it's a quantity issue.

But there's a wolverine in the woodpile: Batteries. To be blunt, they suck, as in, expensive to replace and very short lifetimes compared to the rest of the system.

Until or unless ultracaps reach a point where they are on par with batteries for the service you need, reasonable full-on solar installations remain quite expensive.

Installations that use batteries are regarded highly by their owners only until the first battery replacement. Then their wallets straighten them right out.

I have a lowish-power setup, with an unfortunate number of ultracaps (because capacity is very low, about 1/10th that of a battery right now) as the energy storage medium. I did it both to give my ham gear a constant supply, and to explore what would actually work. It took a custom controller design -- ultracaps don't act even remotely like batteries -- and it took me quite some time to put it all together and make it work like I wanted it to. There are way more panels than you'd expect because of that 15% number (my panels are cheap ones), and there are way more ultracaps than I wanted to expend room for, but I did have the room, so I kept at it. It works great, and it isn't going to need service for decades unless there is an actual component failure or a severe weather event (large hail, for instance.)

Trying to do this for a full house load? A typical US house? Not yet, I'm afraid. There will be tons of compromises to make in appliances, lights, and lifestyle, and in the end, you're not likely to have the same lifestyle you had prior to your switchover.

The battery problem will probably be solved. One way or another. Eventually. I have no idea if solar panel efficiency will get up into a range where the costs and space will fall within the range needed to go truly off grid. That's a physics question in an area where I have nowhere near enough knowledge. But right now? No.

Which brings us to on-grid, grid power use mitigation. Now that is an interesting area, and we can leave batteries right out of it, as peak power also comes during peak power use (right now... electric cars may change that.) But it involves all kinds of compromises for the utilities if it is adopted in any kind of mass manner. They will need power storage, as I understand it at the moment.

Full-on solar is a great, great thing with huge potential (ha, a pun, hooray), but it's not a panacea by any means except in very rare sets of circumstances that involve very large amounts of money and large areas of space for the panels.

If you trust all that, and you believe it isn't vulnerable to the NSA and hackers, that's your call to make.

What about when you need a huge bunch of CPUs to compute something? That's an aspect of "the cloud" that actually seems reasonable. As long as you don't put anything you want kept secure out there, of course.

the first responsability of the CEO is to protect the money of the shareholders and make it profitable

Exactly right. Add just a smidgen of shortsightedness and some pressure from the board, and you have the perfect storm of next-quarter-itis.

After a few quarters like that, the CEO takes off for the next company, as the company tries to put out the fires they left behind them -- fired experts, cheapened and crippled products, new hires that don't know much about the domain, insufficiently-tested but out-the-door-anyway products...

Yeah, responsibility to the shareholders. Which means: Short term thinking and cannibalistic profiteering. That's the US corporate mantra, right there.

+1, informative

thank you

i was talking about a more local electrical arrangement

but yes, long distance, that's a complicated topic, what distance are you really talking about and what other interconnections do you need? dc does have advantages in many cases, especially very long distance

but now we are very far away from the topic of a guy charging his laptop and running some LED lights

The advantage of AC has always been that it is easy to change the voltage up and down with a transformer; DC requires more equipment and some losses to convert.

That being said, transferring AC power between separate grids requires making sure the phase of the power transmitted matches from the two grids (so that the power from the two grids doesn't cancel or ring), which is difficult and expensive. This is not a problem for DC, so DC lines are used in cases such as where power is transferred from another grid to increase the capacity of an existing grid, or between countries that use different frequency power.

Capacitance between the AC phases (usually 3 phases are transmitted at once over a line) or between the line and the surrounding soil or water causes losses that are not a problem with DC. Therefore, undersea high voltage lines tend to be DC.

Overall line loss is also lower per 1,000 km, so very long distance transmission lines sometimes use DC.

http://www.quora.com/When-and-...

thank you, dc genuinely has greater fire hazard implications than ac

as for health, it is a bit more nuanced and complex than i said:

Direct current (DC), because it moves with continuous motion through a conductor, has the tendency to induce muscular tetanus quite readily. Alternating current (AC), because it alternately reverses direction of motion, provides brief moments of opportunity for an afflicted muscle to relax between alternations. Thus, from the concern of becoming "froze on the circuit," DC is more dangerous than AC.

However, AC's alternating nature has a greater tendency to throw the heart's pacemaker neurons into a condition of fibrillation, whereas DC tends to just make the heart stand still. Once the shock current is halted, a "frozen" heart has a better chance of regaining a normal beat pattern than a fibrillating heart. This is why "defibrillating" equipment used by emergency medics works: the jolt of current supplied by the defibrillator unit is DC, which halts fibrillation and gives the heart a chance to recover. ...

One of the reasons that AC might be considered more dangerous is that it arguably has more ways of getting into your body. Since the voltage alternates, it can cause current to enter and exit your body even without a closed loop, since your body (and what ground it's attached to) has capacitance. DC cannot do that. Also, AC is quite easily stepped up to higher voltages using transformers, while with DC that requires some relatively elaborate electronics. Finally, while your skin has a fairly high resistance to protect you, and the air is also a terrific insulator as long as you're not touching any wires, sometimes the inductance of AC transformers can cause high-voltage sparks that break down the air and I imagine can get through your skin a bit as well.

http://physics.stackexchange.c...

this experiment is fine if you're doing little LED lights and laptops, but if you're running something like air conditioning or a washing machine you're building a fire hazard and a mortality risk

the decision to use AC over DC was not random nor taken lightly, there are many factors involved (heck, it was a major engineering, corporate, and PR war between Edison and Westinghouse: https://en.wikipedia.org/wiki/... ), but the right decision was made

for our modern world where some people only care about their laptop and smartphone, it does indeed seem silly and wasteful to convert to AC then back to DC, especially if you've ever tried charging electronics in a car. but there are of course many other uses for electricity, and the navel gazing small electronics crowd is but a minor topic

but i do see a time in the future as more people use local solar and other renewables, that a small DC subsystem is made available in the house for electronics like computers

AGL != MSL

Eh, it's kind of like your Android phone not making root readily available. It's there to protect the unwashed masses from themselves. Serious hobbyists (or bad actors) don't have much difficulty getting around the restrictions. I don't think anyone seriously thinks that "geofencing" software will keep a terrorist from flying a drone into restricted airspace. What it will do is keep the "hold my beer and watch this!" crowd from flying their drone into the glide path of a 747.

It is to many people, particularly those that came of age after the internet went mainstream, as well as those that are older and less technically adept.

Like it or hate it, Facebook is the Internet to a lot of people. Try having a brick and mortar business these days without a presence on Facebook. There are countless people that will go looking for something on Facebook long before they think of a simple Google search. Why do you think Google has invested so much effort into social media despite their many failures? They're terrified of people like this.

At the rate things are going the "dark web" isn't going to be warez, criminals, and black hats; it's going to be anything that's not on Facebook and Twitter.

I was actually thinking about their "complex" (understatement) relationship with the Kurds.

The EU isn't a defensive alliance; that's what NATO is for and Turkey is already a NATO member. One that's keeping us from forming a coherent policy against ISIS, incidentally, since our natural allies in the region and only proven effective anti-ISIS force happen to be Turkey's sworn enemy.

When USENET, IRC, and other mediums that were hard to censor were the rule rather than the exception? Now the "go to" places are all for profit enterprises, Facebook, Twitter, Google, et. al. They may profess to follow Western ideals, they may even actually believe in them, but when push comes to shove they'll always do what's necessary to enrich the bottom line.

As an aside, I wonder why the EU is hesitant to consider admitting Turkey? Or why the United States insists on advocating in favor of such a course of action.

Not even close my Suomalainen friend. Not even close. :)