Coal Power Is More Diffuse Than Solar Power

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Solar power being not particularly diffuse
Solar power being not particularly diffuse in South Australia.

One thing I find very odd about the world is that even today when solar panels are being installed from Canada to Tasmania and powering everything from laptops to fish tank filters to cars, there are still people who appear to wake up in the morning and decide that their mission for the day is to tell the internet that solar is too diffuse a source of energy to be practical. And while I have to admire the persistence of some of these people, I really can’t say I’m a big fan of their logic, their habit of rejecting evidence they don’t like, or their general lack of comprehension of the reality of how solar power is currently used in the world.

I will take it as read that the world’s most widely used source of electricity, coal power, is not too diffuse to be practical. If it was, we obviously wouldn’t be in the unfortunate position of using so much of it. So I will compare solar with coal and consider different ways of looking at how concentrated they are as sources of electricity.

Currently I am sitting in Adelaide in South Australia. The nearest coal mine to me is over 450 kilometers away as the crow flies or 561 kilometers as the crow drives. If I was to put a giant rubber ring around the state’s population center and then uniformly stretch it out until it included the closest source of coal it would cover over 640,000 square kilometres, giving my state’s coal power an average output of about 0.00033 watts per square meter. Meanwhile, just meters above my head, solar photons are silently banging against the roof right now and not at all annoying me with their non-loudness. The roof right above me is currently being hit with about 1,000 watts of sunshine per square meter. With 15% efficient solar panels that would come to an average output of about 30 watts per square meter at this location. This makes rooftop solar about 90,000 times less diffuse a source of electricity than the state’s coal power.

However, I doubt many people will think this is the right way to go about comparing them. I certainly don’t think that the people who say solar power is too diffuse to be practical will care that coal power often comes from a vast distance away while solar power is right here. So instead I will look at electricity produced per square meter of land dedicated to its production.

On a typical display this represents 6,500 watts per square meter.
On a typical display this represents about 6,500 watts per square meter.

Recently I wrote about how the Hazelwood coal power plant and its mine produced an average of about 32 watts per square meter, which is much lower than wind farms. Hazelwood is located in a very cloudy location for Australia, but if I covered its entire 3,554 hectares with commercially available, 20% efficient, Sunpower solar panels, it would produce kilowatt-hours equal to about 85% of Hazelwood’s current average output. If these solar panels were instead installed in a better location in the same state they would exceed Hazelwood’s average output and in a great deal of Australia they would almost double it.

Clearly solar power can’t be considered too diffuse if it is possible for its average output per square meter to exceed that of coal power plants. But this isn’t actually the right way to go about comparing coal and solar. This is because in Australia we almost never put solar panels on the ground. Apart from 10 megawatts in Western Australia and a few installations done by people who are afraid of heights, almost all of Australia’s approximately 2.2 gigawatts of solar capacity is mounted on roofs and doesn’t remove any land from its original use. This means that Australian solar power produces more than 50 times as much electricity per square meter of dedicated land than coal power.

While Australians are very disinclined to put solar panels on the ground, this is less true in places such as Europe and India but this still does not make solar power too diffuse to be practical. In the case of India, almost all of their solar capacity consists of low efficiency, thin-film solar panels mounted on the ground which produce much less electricity per square meter than any coal plant operating at its originally intended capacity. But despite this, India is now building solar farms that will produce electricity at a cost of about 12 cents a kilowatt-hour which is competitive with electricity from new coal plants. So while Indian solar takes up more land than coal per kilowatt-hour produced, it’s obviously not too diffuse to compete with it even when coal power is not paying anything close to the full cost of the harm it causes.

While looking at the area of land required is one way to consider how diffuse a source of electricity is, another is to study the average number of kilowatt-hours produced per kilogram of mass required. A rooftop solar system with 15% efficient panels that receives a not-particularly impressive average of 4.5 hours of sunlight a day will produce about 400 kilowatt-hours per kilogram of its total system weight over its lifetime. Whereas coal power, due to the massive amount of coal it burns, will only produce about 2 kilowatt-hours per kilogram of mass required. This makes electricity from rooftop solar approximately 200 times more concentrated a source of electricity than coal power. If the mass of the oxygen required to combust the coal is included then rooftop solar is about 400 times more concentrated.

So despite what you may occasionally see scrawled on the internet, in Australia and many other regions, solar power is a much more concentrated source of electricity than coal in terms of the amount of land it requires. And in India where solar power is more diffuse than coal in terms of land used, it is still competitive with new coal even when coal doesn’t pay anywhere near the full cost of its externalities. And in terms of kilowatt-hours produced per kilogram of mass required, solar power is a far more concentrated source of electricity than coal anywhere in the world and the only thing that can change that is if you make me include the mass of the sun in my calculations.

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51 thoughts on “Coal Power Is More Diffuse Than Solar Power

  • Your logic doesn’t add up for years and including now you have been using coal generated energy to your benefit , then one day your woke up and said solar power was going to save the planet, I find this not logical.

    • Horses to cars.

      Typewriters to computers.

      Film to digital.

      Those transitions were likely beyond your comprehension as well….

      • I think I may have to start paying royalties to Bob the Angry Flower what with the number of times that particular cartoon is relevant in comment threads.

  • I don’t follow what you are saying, nor do I under stand your point, coal energy is a good thing it power my in house internet, hot water, stove, heater, swimming pool pump and keep the lights on at night.

    There is no other technology which can supply my 24hour energy needs. For instance solar power could not supply two of my energy need at the same time, solar could not run the stove and hot water system, and that not including the heater. Solar power does not store its energy, so I can turn the lights on in the night.

    Could you explain more clearly how solar power can supply my energy needs with out been on the power lines?

    • No, I don’t think I can explain it to you, Brian. You just don’t have adequate background knowledge. Come back when you can tell me three ways that it is possible to have power 24 hours a day without using coal.

    • Easy. Solar combined with energy storage (batteries) can supply energy 24hrs per day without power lines. Solar is of course best when connected to the grid to bring down peak power rates.

    • So because it doesn’t fix everything it is worthless?

      I guess a flu shot is worthless too because you still have to go to the dentist huh?

      Solar panels are not, in themselves, the cure all solution. They are simply one piece of the energy solution. Combine solar with wind, geothermal, tidal, offshore wind, wave and biomass and we may not even need substantial storage… but we do also have the option of storage. These will keep your house running 24/7 without reducing your standard of living. Actually, it’ll probably improve your air quality.

  • I think there is a gap in your logic. Whilst I fully agree that solar power gives high enough energy per area to be practical, I have to say that to be fair to Coal in the energy per kg calculation, you would have to consider embodied materials – the materials dug out of the ground to make the glass, aluminium plastics, silicon wafers etc. I do not have the figures, but I would guess that this figure would be much higher than the weight of the panels.

    • When it comes to embodied materials, coal loses. There’s about 500 tonnes of steel and concrete per megawatt of capacity in a coal plant. At Australian capacity levels a coal plant has about twice the of mass of solar power kilowatt-hour produced. If the embodied material of mining equipment, roads, and transportation is included the comparison becomes even worse. And the figure for coal is 200 times more mass per kilowatt-hour produced than solar, mostly all due to the mass of coal consumed. There is no way to look at embodied material can make any real change to that.

    • Then we should do the same for all the materials used to make the coal plant and extract the coal.

    • Solar panels repay the energy needed to extract and process the aluminum, silicon and other materials and turn them into electricity producers in one to three years.

      Coal plants require a constant input of extracted fuel for their entire lifetime. The cars of coal never quit rolling from mine to plant.

      And it takes a lot of energy to build the coal plants and railroads.

      Solar panels are very slick inventions. One of the most clever things mankind has ever developed. Just think, input a couple of years of energy and get 3, 4, 5 or more decades of energy back out. No dangerous wastes. No pollution. Just clean, cheap electricity.

  • What about the rooftop fires that has been going on?

    • Minor problem. Some Australian dimwit company made some installation errors.

      At least they didn’t build nuclear reactors in a tsunami zone….

    • Provide evidence of these fires. Can you show that there have been more than say three? Or that rooftop solar is a greater fire hazard than other electrical devices? Adelaide alone had 11 air conditioner related fires in 2012.

  • Considering the size of the power station and the amount of power which it generate for the population I consider it to be efficient. Now the issue of solar panels, tell me how long have you been dependent on the grid for, before you decide to sell power back to the grid with your rooftop grid connected system in order to make money?

    • So just because used need grid power to produce solar panels makes them useless? I mean it’s not like we can use grid power to make solar panels, and then use those solar panels to make electricity to make more solar panels… and then get off of using grid electricity… cuz since we used grid power to make the first ones they must all be tainted…?

  • We are calling on the Federal government to establish an enquiry as the reports flowing daily within Australia of house fires related to rooftop grid connected system. There needs to be more accountability in this area including the homeowner not maintaining all doing maintenance on their solar array or keep a constant lookout for problems that might occur, therefore is in the best interests of enquiry takes place, and established that a direct cause of these negligent fires. Whether fires resulted under government standards or the homeowner was clearly negligent, the enquiry will uncover the truth.

    In regards to your comment,

    Well I don’t know about any dimwits , but what I do know is that the Australian standards are causing the grid connected rooftop solar power house fires, yet again firemen turned up to a house with grid solar power where the houses burnt to the ground. The house could not be saved due to the intense heat and high voltage on the roof from the solar array, firemen say the blaze reach seven thousand degrees make it impossible to even to do anything, but contain an perimeter to protect other houses.

    So as you can see there is a huge problem for the firemen and the general public that’s why an enquiry needs to be established immediately into these matters.

    • Mark, what fires? Can you provide evidence that there have been more than say three house fires related to solar power in Australia? Even with about a million installations I’d be surprised if you can find that many. While any electrical applicance is a fire risk, thanks to Australian and international standards the risk from home solar is extremely low. And also, why do you think Australian fire fighters are scared of electricity from rooftop solar that might be 55 volts of DC current at perhaps 6 amps when they deal with normal Australian AC current of 240 volts and at least 10 amps all the time? Australian firefighters are not cowards or idiots and I assure you rooftop solar does stop them from doing their duty.

      • Yes certainly I can provide evidence however is not in my interest to hand over such information to people like yourself who discredit this information at hand. Just as the article replies today people still wake up in the morning and pretend these things are not happening. Therefore is not in the interest in supplying that evidence to a sceptic given a grid connected solar power is going up in fire under the Australian standard. However I can inform you have been more than three rooftop grid connection house fires under the new current safety rules. And just for the record rooftop systems exceed 300 V DC and go above but 1000 volts DC certainly a concern for firemen and not the 55 V DC which you claim.

        • Mark, if you are going to say that Australian firefighters stand by and let Australian houses burn to the ground, surely you can’t be surprised that people don’t believe you. It’s an extraordinary claim. Australians don’t like people who say things like that about our firefighters. So come on, put me in my place! Show us evidence that Australian firefighters are letting houses burn. I promise not to use my magical powers of discrediting on you.

        • Mark, I’d like to see you prove that you aren’t just making stuff up.

          Give us a link to a reliable source that reports more than three solar related roof fires.

          Tell us who makes a grid tie inverter that will accept 1.000 volt inputs.

          • I do have a grid connected solar system which is rated above 1000 DC; I have 60 panels at 60 V which is divided into strings operating at 1800 V DC, approved by Australian standards. The reason I chose the high voltage solar system/ inverter, so I could save on wiring cost, at the higher the voltage level, the less wire is required, I save $3,000 on installation cost by going this way.

          • Given your grammar, I’m going to guess you’re not a native English speaker… which also makes it unlikely that you live in Australia.

            But even so, your claim that higher voltage levels are cheaper because you require less wire is dubious at best. While you can have thinner gauge wire due to the lower current of high voltage systems, you have to have significantly higher grade wires with much better insulation for the higher voltage – which are more expensive. They also need regular inspection at that voltage as, if the insulation breaks down, it really could start a fire, so any instillation with that type of voltage would require an annual inspection as well as a fail-safe to cause the whole system to shut down at the first sign of trouble – negating the fire risk. This system would also negate much of your “savings” due to reduced wire gauge.

            So, if this is true, I would call a licensed electrician to double check everything IMMEDIATELY. But then again, I’m American, electricity might work differently here.

          • The specs of inverters specify a nominal DC voltage and a maximum DC voltage. The nominal voltages are mostly in the range 400 to 600V, the highest specified max. voltage I have seen is 1000 V. This is both true for string and central inverters.

            Around the turn of the century there was a trend to put more and more modules in series, and thus create higher DC Voltages and thus lower DC currents, reducing DC resistance losses. Safety concerns halted this development.

        • lol. this is one of the most hilarious responses i’ve ever seen. 😀 ‘yes, i have data to back up my point, but i won’t supply it, because than someone might see what nonsense it is.’ 😀 lol.

        • Seriously Mr Sock? How about a link to a news article or two?

        • Seriously? “Not in your best interest” to back up your own claims?

          How are outside parties such as myself supposed to believe a word you say when you won’t substantiate anything? Let any fanatics twist anything they want – show me the evidence and let me decide for myself, because until then, how am I supposed to know it is not you who is the fanatic?

          Your logic escapes me…

      • Well, while I support your point here, to be fair DC voltage is significantly more dangerous that AC voltage…

    • There is a fire risk having any electrical service to your house. There is a fire risk having any electric or gas appliance to your house. Proper codes and modern knowledge of electrical systems has massively reduced the risk of our modern technology.

      The safest electrical system from a fire and electrocution standpoint is a low voltage DC system. Ultimately your internal AC wiring and your grid link is your biggest risk factor. If you moved your appliances and lighting to a LVDC system powered by solar panels and batteries you would actually reduce your fire risk.

      Should we move back to gas lighting and heat/power? Perhaps move back to candles and kerosene? That’s no good! Let move back to before fire and live in caves- best from a fire risk standpoint. Except for pesky lightning and those forest fires. Oh well, small price to pay.

      Actually there is a great risk to the gas and coal companies paying a shill like you $10 an hour to sit at home and re-regurgitate their lies and spread fear, uncertainty and doubt. (Anyone else notice this every time one of these pro-Australian solar stories hits this website?) They may be wasting their money on someone as incompetent as you and as a result be bloody obvious about it. Pay no attention to the man behind the curtain!

  • Hazelwood power station is quite beneficial is produce prosperity for the nation and provided electricity needs for each individual. Logically speaking solar power has been known to cause fires, yet you mention none of this here, logically you would of, but you can’t bear to stand logic that this is occurring and information that has been provided is stressful and truthful logical.

    • Hazelwood kills workers inside it with asbestos, kills people in the Latrobe valley with pollution, and through global warming contributes to bushfires, floods, and drowning Thai people. So the electricity it provides comes at a very substantial cost. Costs that are much higher than any from solar power. And what fires? Provide some links please, because you can’t seriously be expecting people to take anything a sock puppet says at face value.

  • Wow, Ronald, you have some serious stalkers. They must have an RSS feed for your articles somehow… would be nice to know how, as I’ve been wanting to have an option to subscribe to author posts included under articles. 😀

    • Some serious stalkers or one stalker with a drawer full of sock puppets?

      You can follow individuals on Disqus I believe.

      • correct, i think it’s basically one person with many, many names & nicknames.

        • Can we make a company bet pool?

          I’ll put $20 on 2 people with a lot of different names: There’s two distinct sets of grammar throughout all of these different comments, but among each set of grammar, they have similar diction, flow and tone – as well as eerily similar and misinformed arguments…

          • And actually, off topic note – these misinformed comments actually help me. They give me the opportunity to look up the real facts so that when some uninformed person in real life brings it up, I know up-to-date, cite-able statistics with which to correct these fallacies.

            But it would be nice to get some new fallacies… I’m getting pretty good at refuting these ones…

      • You have to expect some puppet jealousy when you’re only one degree of Kevin Bacon removed from Miss Piggy.

    • What can I say? I have lots of ex-lovers. But my lovers all soon burn out due to how intense I am and the experience leaves them broken, hollow shells of people with destroyed grammar.

  • Coal/nuclear proponents cherry pick a metric, where they think they can beat solar. Than you try prove that solar can win on this metric, by stretching its meaning. I think it is more useful to show that the metric is irrelevant: By using only a small fraction of the earth surface solar can provide all of humanities energy needs.

    • It is of course the economics that determine what energy sources are used. No one sits in a board room and decide what sort of generating capacity to build based upon square meters needed or kilograms of mass required. And while I could give a lesson on economics, that might bore some people and if you look at some of the comments here you can see that’s it’s not the sort of thing my special fan club is likely to grasp. And I do mean special. So if people are going to be silly enough to say that solar is too diffuse to be practical I will amuse myself by writing about how on their own terms, whether looking at square meters or kilograms of mass, solar is a more concentrated source of electricity than coal. On another day I might write about economics. Just not today.

  • This is an excellent article.
    I do not live in Australia, but I think the country can become a leader in clean renewable energy.
    The country should encourage families to buy solar panels though tax breaks and incentives. Australia has huge amounts of empty land where photovoltaic and concentrated solar power stations can be constructed.
    And with the country’s enormous coastline, offshore wind farms can be installed to generate electricity. Slashing Australia’s high carbon footprint should not be difficult at all.

    • Thank you. It’s nice to have a kind word.

      • You are welcome.

  • We supply solar power air conditioner which is combined with PV and heat pump. We have 11000&12000BTU solar air conditioner. More info, please visit

    • This is annoying, but at least I can see what this person is getting out of their spam.

  • Great article. I love the reaction from the sock puppets! I for one can admit my true name.

  • The title of your article is not accurate, because coal is in reality CONCENTRATED solar power that was captured millions of years ago by ancient plants and converted into coal under tremendous heat and pressure beneath the earth’s surface.

    It is a scientific impossibility for a concentrated product to be less diffuse than its original component.

    And what happens when the sun does not shine?

    Your article is specific to your neck of the woods, and has little viability in the US, where coal power is much more prevalent and the sun does not shine nearly as much.

    Adelaide averages at most 13 days of rainfall a month according to this link:

    Most months the total number of days is in lower single digits. This means the sun shines in Adelaide on average nearly 80% of the time.

    In areas where sunshine is not nearly as constant and coal more prevalent, solar energy is much more diffuse.

    Your statement on coal being more diffuse than solar is misleading because it is specific to your location and has little relevance beyond the specific conditions surrounding Adelaide.

    And here are some local links pertinent to Adelaide and Australia in general detailing problems with solar energy:

    As usual, I think we are only getting the better half of the story here.

Comments are closed.