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1. The energy density of sunlight hitting the Earth is about 1360 Watts/m^2.
2. The atmosphere absorbs enough of that so the amount hitting the ground is about 750-850 Watts/m^2. Figure about 800 W/m^2.
3. A 22% efficient panel can then pull in 176 W/m^2.
4. But that's peak - you'll only get that much at noon on summer solstice with clear skies. You have to factor in night, movement of the sun, weather, dust buildup, weather, etc (capacity factor). The average capacity factor for fixed mount PV solar in the U.S. is about 0.145, with the desert Southwest peaking at around 0.195. So that brings your average PV solar power generation down to just 25.5 W/m^2 (34 W/m^2 in the desert Southwest).

   That means installation large enough to power the average home (10399 kWh/yr / 8766 hours/yr = 1186 Watts) is about 1866 W / 25.5 W/m^2 = 73 m^2 or a 12.8 kW system (55 m^2 in the desert Southwest, 9.7 kW). Although that's based on an average - you'll have a shortage of power in winter, so will probably need an even bigger PV installation to get you off the grid year-round.
   
   That quantity of PV panels costs several tens of thousands of dollars. On the other hand, a reflector/concentrator that size can be made for a few tens of dollars. Though the added bulk will increase the mounting and maintenance costs. So you can see where the guy in TFA is going with this. (I left out cost of mounting and voltage regulation circuitry since I figured it'd be about the same for both cases.)
   
   The other option is to just allow plants/algae to collect solar energy. They use it to convert sunlight, CO2, and H2O into sugar, starches (sugar molecules glued together), and wood (starch molecules glued together). You can then use those as fuel. The efficiency is much lower (around 1% or less). But plants grow and reproduce on their own, so manufacturing cost is zero (negative in cases like weeds where we're actively trying to prevent the plants from growing). You only have to pay for harvesting and processing. Human global energy consumption is about 170,000 TWh per year, which at 8766 hours/yr is 19.4 TW. The rate at which energy is stored chemically by photosynthesis worldwide is estimated to be several hundred TW.

Go on, do the math. And by that I mean the full chain, for both. Getting the fuel, transporting it, storing it, and so on, and so forth. It does happen that if you do that, the "green" suddenly isn't so green any longer.

[citation needed]

This is all hard to follow, but I take it that AC is trying to say that the transport and storage of fuels to be used for EV somehow make them less green than the transport and storage of fuels, then burning them in vehicles designed to burn those fuels?

Well, if that is the case, we always have to remember that the electrics tend to get pretty good MPGe. the Nissan Leaf gets an equivalent 112 mpg https://www.autobytel.com/top-...

In addition, we can charge the EV via a home solar system, negating the transport and storage issue altogether. https://news.energysage.com/so...

But the way I like to look at it is let us assume instead of the present situation, Electric cars are dominant.

So someone comes along with this idea that we should all convert to internal combustion engines with all of their complexity, and install a nationwide system of trains and trucks to deliver fuel to neighborhood refueling stations - to create an infrastructure of an immense amount of transport of flammable materials.

All this to replace plugging our vehicles into an electric outlet. All to replace a multiplicity of energy sources. Solar/wind/nuc/coal/hydro can produce the energy for EVs; with a very specific energy source of petrofuel - with a very minor ethanol component.

Whoever came up with that idea would be laughed out of town.

Yet we have people defending that very system as somehow superior.

http://www.dry-it-out.com/cool...

A 10m x 10m room x 2m ceiling requires 12KW to cool it. I made the numbers easy to simulate an entire house and give 100sq meters of panel.

https://dothemath.ucsd.edu/201...

A standard solar panel produces about 250-300W per square meter in such regions. Therefore you'd need about half your roof space to cool just one room, and nothing else. Call it a two-storey house (upstairs and downstairs) and you can *just* about cool the house if you do nothing else with it.

https://news.energysage.com/12...

"As of January 2018, the average cost of solar in the U.S. is $3.14 per watt ($37,680 for a 12 kilowatt system). That means that the total cost for a 12kW solar system would be $26,376 after the 30% Federal ITC discount"

You would literally be spending something on the order of $35k just to cool your house. That's an annual wage. If you can't afford the air-con (notice that the article is just as much about "poorer countries can't afford air con, hotter countries cost even more to air con), $35k on top of the investment to power it is a huge amount.

https://www.ovoenergy.com/guid...

That would buy 437,500 KWh of electricity in India, for example, which would keep that same 12KW powered for.... 99 years.

What you're asking is "Why can't people just spend 100 years of their cooling electricity usage in one hit so that they don't have to pay for any more cooling? On top of the price of the cooling system, and not including maintenance, replacement, fitting, etc. of either."

That's ridiculous. You're just pulling numbers out of your ass.

https://news.energysage.com/ho...

"In 2018, most homeowners are paying between $2.71 and $3.57 per watt to install solar, and the average gross cost of solar panels before tax credits is $18,840. Using the U.S, average for system size at 6 kW (6,000 watts), solar panel cost will range from $11,380 to $14,990 (after tax credits)."

Even that is incredibly cheap; I'm in Canada and here you're looking at $25-30k minimum. Sure that can be reduced with "tax credits" but that doesn't make the system "cheap"; it just means you're getting everyone else to pay for your electricity.

I mean, have you even looked at the price per watt in recent years?

Sorry, your link is very misleading

The cost of solar panel (plus installation) comes to $2.71 ~ $3.57 per watt

Plus, the average gross cost of solar panels before tax credits is $18,840

That's $18,840 extra cost a new home owner must cough up, in California

https://insideevs.com/tesla-re...
https://news.energysage.com/wh...
Dude, just because you work for Communist CHina does not mean that you have to be this stupid. Plenty of search engines to show you that you are wrong.

So how does that view fit in with the fact that the tariffs will reduce to elimination over the next 4 years?

Its about cancelling out the 30% federal solar tax credit, also known as the investment tax credit (ITC), which was extended in 2017 with gradual decreases each year until phase out in 4 years (100% phase-out for residential, 90% phase-out for commercial).

Funny how all that lines up.

PS and I've seen arguments that renewables can't supply much of our energy because of bad forecasts like these. We knew those arguments were wrong and now with renewables making up large percentages of energy usage in many countries we've been proven right. Both wind and solar can each provide as much energy as the world uses.

Oh boy, is the coal brigade ever going to swarm all over you!

But yer not wrong. Obviously the coal and increasingly the petrochemical industries are finding useful idiots who are stuck in the 1960's with regards to their understanding of energy production.

Meanwhile I can see the wind turbines not too far away providing enough power that they are moving beyond just peaking. And the solar installs are popping up everywhere, with many eschewing the grid period.

We can see solar installations in Alaska, previously cited as a useless place for solar, but it turns out they can save a lot of money and safety factor by saving the diesel fuel for winter when the sun don't shine. Kinda weird looking at circular solar arrays though.

People can go to Harbor Freight and buy solar panels. A 100 watt one is $149.00 at the moment.

Solar systems are now about $3.17 per installed watt to start with. That's a 10 percent drop from 2016. http://news.energysage.com/how... That makes a 10 KiloWatt system cost around $22K.

And if you aren't building in a place already served by mains power, you might be surprised how much installing the mains power will set you back. Old commie FDR's Rural Electrification Project isn't around any more, so you pay for the poles, the wires, and the transformers and installation of each out of your own pocket

Times change, and we don't use steam locomotives to get around any more, or DC mains, and outside of the Amish, horse drawn buggies are used for entertainment.

Now the unemployed coal miners that we are supposedly going to put back to work mining coal, a Government assisted project worthy of old commie FDR - howbow we set the lads up with work involving production of newer energy sources and the equipment involved with it? The rest of the world moves forward while many of us seem dead set on heading back to the late 1940's.

'I winter in Germany, solar output is almost non-existant.'

Get a brush until climate change takes care of the snow.

"Do solar panels work in the winter?

A common myth is that solar panels do not work during winter, but in contrary, the cold temperature will typically improve solar panel output. The white snow can also reflect light and help improve PV performance. Winter will only hurt solar production if the panels are covered with snow."
http://news.energysage.com/sol...

"Check your idiot assumptions 1st"

I think you've confused panel power output with power per square meter. The former is a measure of capacity, the latter is a measure of efficiency. Solandri's computation needs w/m^2 and 160 w/m^2 appears to be reasonable for typical current panels. see http://news.energysage.com/wha... (BTW -- Solar World Panels don't appear to be especially efficient -- at least not if you believe energysage.com)

The U.S. isn't any better

A few numbers
http://news.energysage.com/how...

In 2017, most homeowners are paying between $2.87 and $3.85 per watt to install solar, and the average gross cost of solar panels before tax credits is $16,800. Using the U.S, average for system size at 5 kW (5000 watts), solar panel cost will range from $10,045 to $13,475 (after tax credits).

Last I looked a Dollar a watt was breakeven with net metering in place and no incentives.

Some parts of the USA are prone to get hail which causes recurring damage on roofs. Fortunately I no longer live in one of those areas. Insurance companies really don't like paying for hail damage on roofs.

Indeed, mine finally ended up switching to a depreciated value plan for that kind of damage. Don't know if Europe has any of that problem. Either Hail, or insurance companies.

Allegedly, modern solar panels are more resistant to hail damage than typical composite asphalt roofing material (and probably better than wood shingle/shake or spanish tile roofing too) so if over a few year period, it helps save a roof repair (or two), that might be a thing on the plus column for these new fangled solar roofs...

I'm interested in what this solar roof would be like, but if it is like a metal roof, I don't know if that would be any more problem free. Metal roofs can have quite a few problem in residential installations (e.g., condensation, noise, ice dams), so it isn't a panacea. Also the current generation of metal roofs are generally painted with IR reflective coatings, but current generation solar panels are generally transparent to IR. I don't know about solar roofs and there may be some attic heat issues that might be specific issues with a solar roof if they aren't much different than current generation solar panels.

This study which obviously isn't on whatever roofing Tesla/SolarCity plans, does indicate there is some savings, and I suppose if they designed their system right, they could do even better.

I'm looking into putting some radiant barrier foam panels under my roofing material when I get that done, mostly because panels aren't an option for me, and my power provider is TVA nuclear and hydro, so it's marginal in terms of utility, let alone costs, or tax savings, but cutting the heat to my attic where my HVAC is could be worth it.

I could just do it in the attic, but I'm not sure how much that'll help. Or if it'll be more difficult, since there's of substructure under there that will complicate things. At least I can have a uniform set up if I put it under the shingles, though I will have to worry about the sun-exposed South side.