A matter of scale, distance & speed. (assuming we are talking about electrically driven engines like ion drives or the proposed EM engine.)

If nothing else, the sun gets weaker the further away you get. Out at the edges of the solar system it's almost negligible.

Given that mass directly effects net thrust & fuel range, smaller craft working in the inner solar system may well be better off sticking with solar over a bulky reactor.

Larger and or longer ranged ships should start to favour fusion reactors and such.

Unless of course they manage to miniaturise the fusion apparatus, or perhaps harness quantum effects like matter/anti-matter. etc. etc.

Surface area to volume ratio also starts to shaft solar power the bigger the ship gets too. The panels would have to get exponentially bigger along with the ship/engines.

I couldn't tell you exactly where, but there will be natural tipping points between the practicality of one over the other.

Edit: The calculation would mostly be the ratio of energy produced to mass of the generating apparatus. The point where a fusion reactor (inc it's fuel) can produce more required power per unit of mass than solar cells (and associated gubbins), is the point where it becomes more efficient for most spacecraft.

Though solar still has a clear advantage where indefinite operational duration is a factor. (fusion requires fuel, albeit in small quantities)

Can you build a solar powered long-distance spacecraft? Or would fusion be better?

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*related=http://videosift.com/video/solar-powered-water-wheel-cleans-baltimore-harbor#comments

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I havn't dived enough into it. I saw the "if we covered only this blip of the us, we could power the entire nation" argument a while ago and this is what I got from a quick google search. Not in a position to explore solar power myself as a means so I haven't been paying that much attention to it.

What part of "do not have a choice" do I not understand? How about the subject of the 'choice' you are denied. Now that you have clarified that you don't have a choice about how the electric company pays you, or how solar works, I'll reiterate, you still DO have a choice about how to use the power you generate. Making better use of that choice would serve you well, but you seem intent on claiming it's all out of your control (and that you're forced 'at gunpoint' to sell all your production cheap and buy it back expensive rather than find a way to use it directly). I'm intent on making the best use of the choices available to me (and I bet to you) in order to make intelligent choices about my energy, choices that have saved me thousands to date, and should save me tens of thousands in the long run, and save uncounted tons of CO2 from being produced. You have instead invested in a system that now serves your needs terribly, and now want to tell others how solar is not economically viable or green, both of which are absolutely backwards from my experience and research.

You were not kidnapped, you walked into that guys home and put his gun to your own head. I wonder if you've even investigated 'net metering' in your area, it could make your system work for even you.

OK, so energy cost VS energy produced is ALL you want to compare. Then you MUST include all energy costs to be reasonable, including the energy cost of cleanup of coal waste failures (that right there already totally tips any scale against coal, it can't come close to making the energy that cleanup takes), the energy used in upkeep of coal waste storage for centuries, the energy costs of habitat destruction/reconstruction by coal mining itself, the mining itself, transportation of the coal, power plant operation (construction, upgrading, and maintenance), and the cost of mitigating the 20-40 times the amount of CO2 pollution, health issues, loss of sunlight (solar dimming is real), etc. The list of energy costs goes on and on for coal, while the list for the energy cost of solar panel production and use in some cases is damn near zero (where it's made with leftover chip wafers in solar powered factories it barely takes any extra energy at all, but I do understand that most aren't made that way now).

Double return VS coal, because you get twice as many KWH per dollar with solar PV, or better.

Again with the 'spend more energy to produce one KWH of PV than with coal', show me some data. Everything I can find shows you're 100% wrong if you look at the lifespan of panels which become energy neutral in well under 3 years on average (some much sooner) and last 20-30 years, while coal continues to need more energy to produce more (filthy) energy. Perhaps in the extremely short term you have a point about cost/production, but any time period over 3 years puts PV ahead of coal in energy costs/energy produced, and in their 20-30 year lifetime they do much better.

Coal made power is NOT cheaper than solar made power. If it was, I would not save money with a solar system. I have already saved money with solar VS buying the same amount of coal produced power, therefore solar PV is cheaper than coal. Period. If it wasn't, our electric companies would not be 'farming solar' here as fast as possible, they would be building more coal plants.

Some people support coal because they have been misinformed about alternatives. That's why I have continued our discussion here, because your information is wrong based on my personal experience and research, and I fear you might convince someone to not even look into solar enough to see how wrong you are, how much money they could save (if they do it properly), and how much pollution they could not create.

Um...I DO grow my own vegetables in my backyard too. It's cheaper, and I get far better produce with zero carbon footprint. Another statement you've made that I take personal exception with. It's not a HUGE effort, but is some effort, but the returns are great and totally worth it. I think many people stopped subsistence farming because they're lazy, overworked, and/or live without any place to farm. I've been doing it since I was 12 and ate my first self grown corn, and I've never had reason to question that decision. I've read about people spending $50 to grow $5 in tomatoes...I'm not one of them. I spend $50 on manure to grow >$1000 in produce yearly, and have enough to give >1/2 of it away.

Not a single one of your examples are 'more viable' than PV in every situation, and private owned home solar doesn't take public dollars away from public power projects. I looked into wind-it's way more expensive for the same generation power along with numerous other issues, nuke-also far more expensive with other long term major issues, solar thermal-hardly working as hoped yet in the few, hyper expensive plants in existence, wave-not yet but fingers crossed, hydro-DISTEROUS for the environment and short lived. (You left out geothermal, which is excellent where it's possible.)
Also, most of your examples are not viable for residential use (what we're talking about here), as you said are more expensive (so are bad economic choices), and/or have other serious ecological issues that PV does not.

Money is the only reason to stick with coal or nuclear, and that's only because the companies that use it get away with not paying for most of the true long term costs, and even with that it's now FAR more expensive to buy that coal/nuke power than it is to make your own with PV, leaving NO real reason to stick with coal or nuclear....so what are you talking about?

Great timing on this video. I just ordered an HD DLP last week. I should have it in 6-8 weeks, as I live in a 3rd world country now.

I was shocked they had highly rated SD DLP projectors for LESS THAN $100. I went with the $600 true HD version though with 20x more light output.

But this video also really helps me further conceptualize and realize my solar powered death ray. I want to have a 10,000 one inch mirrors hooked to independently, hyper accurate micro-servos, then have the whole array on a large servo controlled panel that angles towards the sun. With the right control logic, you can have 10,000x the power of the sun focused onto a single, movable, virtual target 1 inch in size. Hot.

Hear, hear...A lonely voice of sanity, crying-out in a wilderness of the self-deluded...

I'd offer...Who gives a fiddler's fuck whose missile hit whose fight club incubator? Missiles found stacked neatly at two United Nations Relief and Works Agency school buildings to-date, and as far as that shit goes who is to say it wasn't the UN who brokered the bomb deal and sent the blue-helmet fucks to deliver 'em?

I have a suggestion: Israels' a big boy now (the 'dybbuk' have come a long way since 1947)... How about the rest of the world back the way back from The Never Ending Storyline of Real-Jew/Fake-Jew vs Persians (2700+ years and counting??) and let all interested parties duke it the fuck out? Oh and by all means, think of the children, consume more news-corp spin, and go out and get yourselves some solar-powered Vitamin D maybe??

I know...Let's identify and list 24/7-365 the names and addresses on news-tickers worldwide of the DAMAGED WHITE PEOPLE who manufactured the ordinance and continue to bank Hanover Phist on regional conflicts worldwide (while stealing $$ from the planet's wage-slaves) and eliminate ALL THOSE motherfuckers??


...'and the world, will be a better place'

I feel like most if not all of these are rhetorical, and you don't really want answers to your queries, but I'll offer some anyway....
I'm not attacking you, but will attack your position that AGW is a fraud.
I have done the MOST impactful thing one can do to minimize one's footprint, I didn't have children. I also grow most of my own food (but I do still eat meat, mostly chickens), I have solar power and water, and I drive far less than 5K miles per year. All that said, I am still probably contributing to the CO2 rise when all the math is done, but far less than most first worlders, and not at all when I'm gone.
You can't really be asking for a physics class here in the comment section, can you? Put simply, CO2 reflects more heat back towards the earth, trapping it in our 'system', making it hotter. It's not the only gas that does this, but it seems to be the most prevalent. The models prove to be imperfect because most of them don't take everything into account, for instance global dimming is rarely included in the math. While CO2 fluctuates naturally, the amount and rate of change due to human production is faster and greater than seen in nature, exponentially so. That means there's no time to adapt to the new environment and greater rate of species failure than in a natural extinction event.
I'll just point out that these articles still try to claim that warmer temperatures will create better growing conditions for crops, a claim that has already been proven wrong, as the problems with extreme weather and drought far outweigh the minimal benefits. That's enough right there for me to discount them, as is the fact that they come from sites dedicated to 'denying'. I didn't need to read any farther.
I, for one, do read the data and interpret it myself...and I come to the conclusion that most climate scientists are minimizing the issues, not exaggerating them, and that 'deniers' consistently ignore any data that doesn't fit their pre-conceived self-serving result.
It seems odd to me that the same people that want to rely on the slippery slope argument when dealing with social issues can't understand how far we've gone down that slope with our climate and deny there's a slope at all, no matter what the evidence shows.

Haha.. a .gov link is about as unreliable as you can get!

I live in the Bay Area. Go to Whole Foods around here, and you can see that it runs on solar power. Go to the DMV or to city hall or any of the other state-run facilities and you can see that they don't (but instead are major contributors to the waste and pollution they purportedly "regulate"). Anyone who really cares about the environment should no doubt become an anarchist and work towards abolishing the state. All of them.

(Surprisingly, in Texas, too, the state is a bit less "crony" when it comes to their energy companies. That is to say, citizens actually have a CHOICE between several energy companies they can use. A friend who recently moved there -- and who is one of those few people who genuinely cares about the environment regardless of the "science" -- told me how pleased she was that she could select a provider that uses wind power to generate the electricity.)

Still, scientific consensus is dubious.

(Note that the 97% statistic remains unclear as to whether it is 97% of 75? or of 65? Or less? The fact that the 97% consensus paper is false, however, does not mean that "climate change" is or is not happening. Only that that is a bogus statistic.)

Comment hidden because you are ignoring dag. (show it anyway)

I think if was a clean energy solution - it would probably fly. Solar powered condoms?

They're not actually solar powered lights, at least, not in the sense that we think of them. They're more like light tubes than actual lights.

Anyway this is a *dupeof=http://videosift.com/video/DIY-lights-from-2-liter-soda-bottles-with-NO-electricity

was kinda wondering when people were gonna tell africans about solar power.... they burn nasty fuels for light when the power company cuts off their power... i hear they have a lot of sun there. i bought a solar garden light for $2.50.. i bet it cost less to make.

soon...

From Doonesbury website:

"They're a smaller country, and they've got lots of sun. Right? They've got a lot more sun than we do."
—Fox News commentator Shibani Joshi, on why Germany's solar power industry is doing better than ours