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What are the limitations of solar energy?

Discussions of conventional and alternative energy production technologies.

What are the limitations of solar energy?

Unread postby DesuMaiden » Wed 04 Feb 2015, 18:23:58

Anyone can tell me? Are solar panels made of any rare earth minerals or other rare materials that are scarce and running out of? Are solar panels a reliable source of energy? Is it intermittent or constant? I just want to know if solar energy is a reliable source of energy.
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Re: What are the limitations of solar energy?

Unread postby GHung » Wed 04 Feb 2015, 18:43:51

Crystalline panels are basically silicon (glass) doped with small amounts of 'rare' metals.

Reliability? High in my experience. My first panels are in their 21st year of continuous use and still outputting full power. The performance of my balance-of-system stuff (charge controllers, inverters, etc,) has been stellar as well. The modular nature of the system (each array/controller combination is a stand-alone system) means if there's a failure, the whole system doesn't go down. I have four array/charge controller sub-systems. If one goes down, I'll still have about 75% production capacity until repairs can be made.

Intermittant? Of course. They don't produce unless the sun is shining (produce some on cloudy days). That's why off-grid folks have batteries. Intermittancy is something you can adapt to with a little effort. No big deal here. We also have a diesel generator that charges the batteries; rarely gets used. Off-grid inverters have an input for a generator and manage charging.

Limitations? Unless you have a very large system, you don't want big loads like electric heat, electric hot water, electric stove/oven, etc., though I know folks running smallish high-efficiency heat pumps. Paired with wood heat/ passive solar and solar hot water, along with propane cooking, we live quite well. We have an induction cooktop for when there's a surplus of PV production.

What we do have? Dishwasher, microwave, electric clothes washer (propane dryer and clothes line), lots of electronics, vacuum cleaners, power tools, lighting, toaster, food processors, dog dryers, lots of fans, a small AC unit for the bedroom, electric dehydrators, and lighting of course. Some usually gets used only on sunnier days. Managing surplus production becomes intuitive and can be automated. A lot of surplus gets dumped into our big hot water tank.
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Re: What are the limitations of solar energy?

Unread postby pstarr » Wed 04 Feb 2015, 19:06:40

"What are the limitations of solar energy?" plugs
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Wed 04 Feb 2015, 20:27:08

The biggest problem with solar PV is the difference between rated power output and real power output. For example, I have 2.8kW of panels on my roof. If the sun shone at full noontime intensity 24 hours per day, I would get 2.8kW x 24 hrs/day x 365.25 days per year or 24,545kW-hrs per year of power.

What is actually measured by my power meter has averaged 3744kW-hrs per year over 5 years. That means actual power production is 15.25% of rated output - a typical figure for a Temperate climate and high quality monocrystalline PV panels.

So to run a residence off the grid using solar PV, one needs to install about 14X the number of panels you think you need - 7X to compensate for the measley 15.25% output and another 2X so that you can charge batteries for when the sun doesn't shine - and I'd suggest about 3 days of battery storage.

This makes for VERY EXPENSIVE electricity. Your PV panels and inverters might last 25-30 years, but you need all new lead-acid batteries every 10 years, or new nickle-iron batteries every 30 years.

That makes solar electricity about 12X as expensive as grid power today - $0.117/kW-hr for the grid, or $1.40/kW-hr from your roof in a Temperate climate zone. And you will still experience a power outage every time you have cloudy days that last longer than your 3 days of battery capacity.
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Re: What are the limitations of solar energy?

Unread postby vtsnowedin » Wed 04 Feb 2015, 20:29:25

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Re: What are the limitations of solar energy?

Unread postby pstarr » Wed 04 Feb 2015, 20:30:48

KaiserJeep wrote:The biggest problem with solar PV is the difference between rated power output and real power output. For example, I have 2.8kW of panels on my roof. If the sun shone at full noontime intensity 24 hours per day, I would get 2.8kW x 24 hrs/day x 365.25 days per year or 24,545kW-hrs per year of power.

What is actually measured by my power meter has averaged 3744kW-hrs per year over 5 years. That means actual power production is 15.25% of rated output - a typical figure for a Temperate climate and high quality monocrystalline PV panels.

So to run a residence off the grid using solar PV, one needs to install about 14X the number of panels you think you need - 7X to compensate for the measley 15.25% output and another 2X so that you can charge batteries for when the sun doesn't shine - and I'd suggest about 3 days of battery storage.

This makes for VERY EXPENSIVE electricity. Your PV panels and inverters might last 25-30 years, but you need all new lead-acid batteries every 10 years, or new nickle-iron batteries every 30 years.

That makes solar electricity about 12X as expensive as grid power today - $0.117/kW-hr for the grid, or $1.40/kW-hr from your roof in a Temperate climate zone. And you will still experience a power outage every time you have cloudy days that last longer than your 3 days of battery capacity.

Good. Get more panels. You're rich. And remember to buy plenty of batteries. I recommend molten-salt. They use them in space.
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Re: What are the limitations of solar energy?

Unread postby DesuMaiden » Wed 04 Feb 2015, 20:58:11

GHung wrote:Crystalline panels are basically silicon (glass) doped with small amounts of 'rare' metals.

Reliability? High in my experience. My first panels are in their 21st year of continuous use and still outputting full power. The performance of my balance-of-system stuff (charge controllers, inverters, etc,) has been stellar as well. The modular nature of the system (each array/controller combination is a stand-alone system) means if there's a failure, the whole system doesn't go down. I have four array/charge controller sub-systems. If one goes down, I'll still have about 75% production capacity until repairs can be made.

Intermittant? Of course. They don't produce unless the sun is shining (produce some on cloudy days). That's why off-grid folks have batteries. Intermittancy is something you can adapt to with a little effort. No big deal here. We also have a diesel generator that charges the batteries; rarely gets used. Off-grid inverters have an input for a generator and manage charging.

Limitations? Unless you have a very large system, you don't want big loads like electric heat, electric hot water, electric stove/oven, etc., though I know folks running smallish high-efficiency heat pumps. Paired with wood heat/ passive solar and solar hot water, along with propane cooking, we live quite well. We have an induction cooktop for when there's a surplus of PV production.

What we do have? Dishwasher, microwave, electric clothes washer (propane dryer and clothes line), lots of electronics, vacuum cleaners, power tools, lighting, toaster, food processors, dog dryers, lots of fans, a small AC unit for the bedroom, electric dehydrators, and lighting of course. Some usually gets used only on sunnier days. Managing surplus production becomes intuitive and can be automated. A lot of surplus gets dumped into our big hot water tank.

Are those rare metals rare earth metals?
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Wed 04 Feb 2015, 21:03:46

pstarr wrote:-snip-
Good. Get more panels. You're rich. And remember to buy plenty of batteries. I recommend molten-salt. They use them in space.


I'm a working man - until I retire May 31st. After that I have one valuable and entirely paid for asset - a tiny home in California. We hope to sell that and trade up to a nicer home in economically-depressed Wisconsin, plus have enough cash to pay taxes and commissions and fees.

I also own 3 acres and a house on Nantucket - at least the wife inherited such. The MIL lives there and I pay the taxes. She thinks it is more important to go on vacation than to fix her leaking roof, so I get to deal with house rot after she dies.

Lucky me. You live in California, too. Do you feel rich?
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Re: What are the limitations of solar energy?

Unread postby pstarr » Wed 04 Feb 2015, 21:16:07

I used to think Nantucket and Martha's Vineyard would be a good bug-out place. I was naive then.
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Wed 04 Feb 2015, 21:17:13

DesuMaiden wrote:-snip-
Are those rare metals rare earth metals?


Boron and Gallium are two "dopants" that get "infused" into Monocrystalline Silicon to make photocells. Neither is a "Rare Earth". Boron is a light metal made from Borate ores, and Gallium is a low melting point metal used to make thermometers that are less toxic than those made with Mercury. Very very minute amounts are used in silicon when "doping" semiconductor junctions.
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Wed 04 Feb 2015, 21:18:56

pstarr wrote:I used to think Nantucket and Martha's Vineyard would be a good bug-out place. I was naive then.


They ship groceries to each island several times per week, on diesel-fuelled ferries and barges.
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Re: What are the limitations of solar energy?

Unread postby GHung » Wed 04 Feb 2015, 21:26:34

KaiserJeep wrote: "The biggest problem with solar PV is the difference between rated power output and real power output.

The problem isn't with the PV panels at all KJ. The problem is people who don't understand what they're buying, and their expectations. The math is pretty simple and all the data is out there. Determine your needs and size accordingly. Hydro plants rated at a certain level, 12MW for instance, don't produce 12 MW 24/7/365. A panel rated at 250 watts should have an average production of 1 kWh per day in a location that has an average insolation of 4 hours per day (1000w/meter squared). Figure in some efficiency loss (10-20 percent) depending on system type. Of course, specific location is critical. If you live on the polar side of a steep mountain, you're basically screwed solarwise.

We have many days when, at certain periods, our combined arrays are outputting 105% (or more) of their rated output.
BTW: I always tell people to add at least 25% to their expected needs, especially with battery-based systems.
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Wed 04 Feb 2015, 21:35:25

I was prepared to pay for as much as I needed, and wanted the Passive Home and would have sprung for LED lighting and efficient mini-splits. But we didn't find lakeshore land we wanted to buy. Still looking, there was some great looking land, just not on the market at that time.

When (if) I buy an existing house, it will have existing utilities. I'll have to think of backups.
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Re: What are the limitations of solar energy?

Unread postby DesuMaiden » Wed 04 Feb 2015, 22:56:50

KaiserJeep wrote:
DesuMaiden wrote:-snip-
Are those rare metals rare earth metals?


Boron and Gallium are two "dopants" that get "infused" into Monocrystalline Silicon to make photocells. Neither is a "Rare Earth". Boron is a light metal made from Borate ores, and Gallium is a low melting point metal used to make thermometers that are less toxic than those made with Mercury. Very very minute amounts are used in silicon when "doping" semiconductor junctions.

So are these elements common on Earth? Is there enough of these elements to make enough solar panels to cover 100,000 square kilometers? That's because we need that many solar panels to make up for the electricity we generate from fossil fuels.
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Re: What are the limitations of solar energy?

Unread postby kublikhan » Thu 05 Feb 2015, 00:19:23

Ok DesuMaiden I'll give this a shot. Someone correct me if I am wrong. I'm going with the assumption of mono crystalline silicon solar cells that are 5 inches square and 6 ounces in weight. Not all of that weight is silicon but I'm assuming that for simplicity. Boron doping amount is assumed to be 0.10 ppmw. 100,000 square kilometers of these solar cells would weigh about 187 trillion ounces. at .10 ppw, the amount of boron would be about 18.6 million ounces, or 527 tons. Turkey alone produced 3 million tons of boron in 2013. So the amount of boron needed to produce 100,000 square kilometers of mono crystalline silicon solar cells would be about equal to the amount of boron Turkey produces in 2 hours. In other words, a very tiny amount of annual boron production. Boron will not be a limiting factor in producing 100,000 square kilometers of solar cells. I believe Gallium is an alternate doping material. IE, if you are doping with Boron you would not also use Gallium. So doing the calculation again for Gallium seems unnecessary.

Or if you don't want to take my word for it, just look at a recent study that looked at the very problem of resource availability for renewables. I linked to this study in the previous thread you started on this subject but here it is again:

When it comes to resource assessments, it is recognised that the overall resource utilisation of an energy system is generally considerably lower if it is based on renewable energies rather than on fossil fuels. The study shows that the geological availability of minerals does not generally represent a limiting factor in the planned expansion of renewable energies in Germany.

The assessment of being “critical” comprises the long-term availability of the raw materials identified, the supply situation, recyclability and the environmental conditions governing their extraction. The expansion of the silicon-based crystalline technology, which accounted for 97 per cent of new systems purchased in Germany in 2012, is non-critical in principle.
Critical Resources and Material Flows during the Transformation of the German Energy Supply System

Sources:
Standard cells are produced using one of two different boron-doped p-type silicon substrates; monocrystalline and polycrystalline. The cells of each type are typically 125 mm (5 inches) or 156 mm (6 inches) square, respectively.
Advances in crystalline silicon solar cell technology for industrial mass production

6oz Of Solar Cells High-Efficiency Mono-Crystalline Cells

Scrap Solar Cells 6oz

The boron specification for standard p-type noncompensated multi crystalline silicon solar cells are typically 0.05-0.15 ppmw B.
DOPANT SPECIFICATION OF COMPENSATED SILICON FOR SOLAR CELLS OF EQUAL EFFICIENCY AND YIELD AS STANDARD SOLAR CELLS

Turkey annual production of Boron: 3,000,000 metric tons
Major countries in boron production from 2010 to 2013
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Thu 05 Feb 2015, 04:36:35

The real limitations to producing monocrystalline solar panels are the embodied energy. This is still 90% true for alternative polycrystalline or rare earth solar cells, but I choose to discuss the premium PV cells I use.

Growing high purity silicon rods from a vat of molten silicon in an electric blast furnace: http://en.wikipedia.org/wiki/Monocrystalline_silicon
Image
...with tiny amounts of "dopant" substances such as Boron or Gallium.

Then you slice the rod into wafers with a precision diamond band-saw and polish those to a mirror finish:
http://en.wikipedia.org/wiki/Wafer_(electronics)
...using more electrical energy, and high tech, high precision machine tools.

Then you fabricate the wafer into a solar cell (infuse a second "dopant" into the surface in yet another high temperature electric furnace to make a "semiconductor junction") and print a thin set of wiring on the surface (aluminum deposition in a vacuum, nothing exotic)(but it uses a lot more power):
Image
...using still more electricity. Then you square off the wafer by cutting the edges straight, to pack more wafers in a panel:
Image
Then you package those solar cells into a panel made from aluminum (a common metal, that one makes in an electric arc furnace, using lots and lots of electricity). The clear film over the top is a plastic film made from petroleum. The wires are the (somewhat) rare metal copper and are insulated with vinyl made from more petroleum.
Image
Then you mount these panels on your roof, using more aluminum for mounting rails, plus steel screws and clips, and wire it to inverters which are complex electronic assemblies using integrated circuits and semiconductors fabricated with more monocrystalline silicon and more dopants and then housed in a heavy wall aluminum or plastic chassis. The fiberglass circuit boards are made from glass fibers from an electric blast furnace, and resins from petroleum, and wiring/printed wiring made from more copper. The big blue capacitors are made from aluminum foil and "electrolytic" chemicals made from petroleum.
Image
If you don't have a power grid to store excess energy, you use batteries:
Image

Get the idea? Manufacturing solar cells requires lots and lots of concentrated electricity for electric arc furnaces, then more electricity plus petroleum to fabricate solar cells, inverters, mounting systems, and wiring.

====> Nobody makes solar panels with solar electricity, everybody uses fossil fuels. Electricity made with solar panels is about 12X as expensive as FF's, for reasons discussed above, so it's not economical to make more solar panels with solar electricity, because it would cost 12X as much, and the embodied energy would never reach the break-even point with expensive solar power. So we simply will STOP MAKING SOLAR PANELS after the cheap oil is gone, because we HAVE NO CHOICE in the matter, we can't afford to make solar panels with solar energy. We might be able to make solar panels with nuclear energy and alternative plastics made from pulpwood, but that won't work because we are SCARED OF NUCLEAR POWER.

So get your high efficiency solar panels today, while they are still available. They will bridge our power-intensive civilization into a hollow remnant where we have enough power to run the internet and light our homes and heat/cool them if you are rich or at least upper Middle Class. The riff-raff (defined as those who believed that currency or even gold was worth something in the Long Emergency) (plus those that trusted "the gov'ment" to care for them) shiver in the dark, no internet, no HDTV. They roam the abandoned cities and towns in search of fuels and wood to burn for heat. Unguarded trees disappear from forests and unguarded woodlots and residential lands and public parks within two years, then wood is more precious and harder to get than oil or gas, as happened recently in Greece. Food and Drink is the new currency.

The solar panels last 25-30 years, by which time we either move into space (my favored plan) or we invent cheap and clean hydrogen fusion and have cheap electricity again (hold your breath for that one) or we enter the die-off phase, bash each other with clubs, and hold a cannibal feast (the most likely result).

The story is basically the same for polycrystalline PV panels or thin film PV panels - we can't afford the embodied energy to make them or to mine and transport rare earths for thin films. The alternative PV cells are slightly cheaper to make but also make less electricity - the numbers are almost identical to the expensive mono silicon case. The solar thermal systems used for space heating are lower tech than PV but they still require materials that must be mined, refined, and fabricated using petroleum fuels.

Wind turbines are made with fiberglass or composites (energy intensive materials) plus steel and aluminum and copper that require fossil fuels and lots of electricity to make or mine or transport. There really are ZERO renewable energy sources that do not require cheap fossil fuels to mine/manufacture/transport/install.

All the "Green Dreams" are like that. Civilization ends when we run out of cheap fossil energy. More than likely - almost a certainty - the nasty 7+ billion humans have resource wars, maybe even nuclear wars. But somewhere along the way, the damaged ecology crashes, and food production stops. Or just maybe somebody presses the nuclear button and the world ends in two hours.

I find that I don't really give a damn. I am 63, I have the means to buy a nice house with no debt, cover it with solar panels, and keep my electricity going longer than I am likely to live, while I grumble about the inconvenience of raising chickens and vegetables, and canning food. But if you are 50 years or younger, you are well and truly screwed. Better figure on squalid and hungry savagery for the latter part of your life, and then you become dinner for somebody bigger and stronger, or the prey of somebody who saved ammunition for 30 years before he found it necessary to shoot your scavenging butt.

Nobody gets off the planet alive after the crash. Nobody survives the crash. The Earth heals and produces a new dominant species in a few million years.
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Re: What are the limitations of solar energy?

Unread postby sunweb » Thu 05 Feb 2015, 08:23:35

I lived off the grid for 30 years so I have walked the walk. At no time was I disconnected from the fossil fuel supply system.
First is the EROI: Scientific studies show it takes years to payback the energy used in solar electric devices. EROI (Energy Returned on Energy Invested) says it takes energy – mining, drilling, refining, transporting, installing, maintenance, and replacement parts – to make the devices necessary to capture solar energy.
Spain’s Photovoltaic Revolution: The Energy Return on Investment by Prieto, Pedro A., Hall, Charles 2013.
http://www.springer.com/energy/renewabl ... 419-9436-3
and http://energyskeptic.com/2013/tilting-a ... -solar-pv/
and B o o k R e v i e w : E n e r g y i n A u s t r a l i a - P e a k O i l , S o l a r P o w e r , a n d A s i a’ s E c o n o m i c G r o w t h by G r a h a m P a l m e r http://www.springer.com/energy/renewabl ... 19-02939-9

Spain’s Photovoltaic Revolution presents the first complete energy analysis of a large-scale, real-world deployment of photovoltaic (PV) collection systems representing 3.5 GW of installed, grid-connected solar plants in Spain. Prieto and Hall conclude that the EROI of solar photovoltaic is only 2.45, very low despite Spain’s ideal sunny climate. Germany’s EROI is probably 20 to 33% less (1.6 to 2), due to less sunlight and efficient rooftop installations.

“Solar advocates can learn from this analysis . . . “ Not looking at the reality of EROI “is not good science and leads to wasted money and energy that could have been better spent preparing more wisely for declining fossil fuels in the future.”

This study does not detail the environmental destructive mining, toxic chemicals or air and water pollution necessary to get the materials for manufacturing and installing solar devices. It is the sun not the devices that is renewable, green and sustainable.
Then:
The devices that are used to capture the sun and wind’s energy are an extension of the fossil fuel supply system. There is a massive infrastructure of mining, processing, manufacturing, fabricating, installation, transportation and the associated environmental assaults. There would be no sun or wind capturing devices with out this infrastructure. This infrastructure is not green, sustainable, or renewable. The making of these devices inadvertently but directly supports fracking, tar sands and deep ocean drilling because of the need for this infrastructure.
This essay has diagrams and pictures of how we get copper, aluminum, glass, black chrome – the chemicals, heavy machinery, and industrial processes that are necessary to make the devices to capture the energy of the sun and wind.http://sunweber.blogspot.com/2011/12/ma ... aking.html

And then: they are really business as usual and we need to stop that.
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Re: What are the limitations of solar energy?

Unread postby GHung » Thu 05 Feb 2015, 09:05:43

Sunweb: "And then: they are really business as usual and we need to stop that."

So you're saying no one should buy solar panels? And who is "we"? Do you assume to know why "we" (whoever that is) want to buy solar panels? Maybe "we" don't care at all about the embodied energy claimed for our solar panels because "we" know there's no hope for our current civilization. Maybe "we" just don't want to sit in the dark while "they" struggle to deal with brown-outs, black-outs, or worse. Maybe "we" just like solar panels. Maybe "we" don't like getting a power bill every month. Maybe we don't think like Sunweb does; in absolutes.

Fact is, there is no "we"; no collective hive mind. There are those who prepare for whatever future they envision, in whatever way they see fit, and those who don't. At least some of us have a plan. What's yours, Sumweb?
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Re: What are the limitations of solar energy?

Unread postby KaiserJeep » Thu 05 Feb 2015, 11:06:54

If you really believe that burning fossil fuels is a sin, then drop out of modern life. Don't own a car or eat food from a supermarket or use electricity or healthcare.

But if you are OK with grid power and cars and medicine and food from corporate farms then spending money on something that produces power instead of consuming it is a good thing IMHO.

Wanting to have electricity is not a problem for me. Make up your own mind, don't accept somebody else's opinion.

In fact, if you are honest, you admit what I have said repeatedly in this Forum: You can be an advocate for the Earth, and champion the genocide of humanity and their food animals. Or you can be an advocate for Humanity, and consider the Earth a temporary home for humans, yours to be trashed.

It's a binary and mutually exclusive choice. Try to take any other position that favors BOTH the Earth and Humanity, and establish once and for all that you are incapable of critical thinking, and an idiot. Once upon a time when our numbers were less than 1B or 125M or WHATEVER that magical fully sustainable population number is, there were other choices. But we passed that threshold of no return around 1805, we are TWO CENTURIES or more into overshoot, and the Earth dies around us. Our infinity of choices has narrowed to two mutually exclusive ones.
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Resistance is Futile, YOU will be Assimilated.

Warning: Messages timestamped before April 1, 2016, 06:00 PST were posted by the unmodified human KaiserJeep 1.0
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Re: What are the limitations of solar energy?

Unread postby kublikhan » Thu 05 Feb 2015, 21:15:01

sunweb wrote:The devices that are used to capture the sun and wind’s energy are an extension of the fossil fuel supply system. There is a massive infrastructure of mining, processing, manufacturing, fabricating, installation, transportation and the associated environmental assaults. There would be no sun or wind capturing devices with out this infrastructure.
Yes, we use fossil fuels to create devices that can then supply energy for several decades without any further fossil fuel input. Instead of directly consuming the fossil fuel as a feedstock. Which enables us to greatly expand the amount of energy we get out of that initial investment of fossil fuel. The extra energy does not harm the biosphere nearly as much if we had to generate an equal amount of energy burning fossil fuels directly as a feedstock. Saves on pollution and stretches our dwindling supply of fossil fuels, a win/win. They can also be recycled at the end of their life at a fraction of the fossil fuel cost used to create it.

if we have to use fossil fuels to manufacture renewable plants, doesn't it mean that renewables are useless? Raugei's answer is a resounding "no". In fact, the EROEI of fossil fuels acts as a multiplier for the final EROEI of the whole process. It turns out that if we invest the energy of fossil fuels to build renewable plants we get an overall EROEI around 20 for a process that leads to photovoltaic plants and an even better one for wind plants. So, if we want to invest in our future, that's the way to go, until we gradually arrive to completely replace fossil fuels!

It seems that this argument is too often brought up to imply that, since PV development and deployment is currently (largely) underpinned by fossil energy, and hence PV is not (yet) a fully independent and truly 100% renewable energy technology, then "why bother" in the first place?

It is worth looking at the issue from another angle. Let us assume that the average EROI of the current mix of fossil fuels (which still represent our main sources of primary energy, globally) is some value X > 1. And let us also agree that we (as a society) need a large and ever-growing share of our energy budget in the form of electricity (to power our computers, telecommunications, trains, home appliances, etc).

Broadly speaking, we therefore have two options:
1) keep using all the oil (and other fossil fuels) directly as FEEDSTOCK fuel in conventional power plants. In so doing, we would get out roughly 1/3 of the INPUT energy as electricity (electricity production efficiency in conventional power plants being ~0.33). This would be the "quick and dirty" option, that maximizes the short-term (almost instantaneous, in fact) "bang for the buck".

2) Use the same amount of available oil (and other fossil fuels) as (direct and indirect) INPUT for the production of PV plants.

Building and deploying a modern crystalline silicon PV system requires approximately 3 GJ of primary energy per m2. What this means is that the c-Si PV system would provide an output of electricity roughly equal to 18/3 = 6 times its primary energy input, which corresponds about 6/0.33 = 18 times the amount of electricity that we would have obtained, had we burnt the fuel(s) as FEEDSTOCK in conventional power plants (option 1 above), instead of using them as INPUT for the PV plant.

A planned long-term investment might be advisable, for instance, aimed at bringing about a gradual transition. The latter is in fact what many have been advocating, often only to be met with rather negative ‘gloom and doom’ reactions by others on a number of prominent discussion forums. It seems as if, in the minds of the latter, the desire to show that ‘the emperor has no clothes’ (i.e. that PV and other renewables are not yet, and might never be in full, a real, completely independent and high-EROI alternative to fossil fuels) overrides all other considerations, and prevents them from realizing/admitting that, after all, it may still be reasonable and recommendable to try and push this slow transition forward.
If we have to use fossil fuels to manufacture renewable plants, doesn't it mean that renewables are useless?
The oil barrel is half-full.
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