> Without going too deep: If you need 100% backup for solar, why use solar?
In addition to this being a lie, if we pretend it's true then there's a sufficient reason. Solar costs less than the marginal cost of other generation except wind.
In addition to this being a lie, if we pretend it's true then there's a sufficient reason. Solar costs less than the marginal cost of other generation except wind.
That is far from a lie.
I just got back from a business trip to Singapore. Among other places, I visited a food production building where we have installed some of our technology for more efficient indoor farming. This building houses some 240 companies. They have a massive solar array sourcing a good deal of their power.
It rained almost constantly for two weeks. That massive array went to nearly zero output during that time.
The only way that building could function was with 100% backup for solar, provided by the grid.
Batteries? The batteries were drained within a day. They could only be replenished by the use of grid power. Once again, 100% backup.
Not sure how you can possibly call it a lie.
This backup can take many forms. Where it makes sense, batteries might be able to help (yet batteries are not magic and they need a reliable power source to charge). A reliable power grid that can provide 100% of the load at any given moment is a must. This grid might be fed by solar (at a different geographic location), wind, hydro, nuclear or burning something. I believe in Singapore's case it is mostly burning gas.
It might seem sensible to think in terms of a wide geographic distribution of solar arrays to supply city A when weather events render the local solar resources unusable. OK, well, at a minimum, then, you need a 100% backup array located elsewhere. Let's call it 1000 km away.
Sounds great. You are betting on the statistical improbability of both arrays being unusable. Weather patterns being what they are, this might be a sensible bet.
What nobody brings into these conversations is: What happens with cities and towns B, C, D, E, F, G, etc.
If both A and C rely on a B's array for weather event mitigation, B's array has to be overbuilt by a massive factor to, at any given time, supply all of A, B and C's power requirements (or combinations thereof). The same become the case for A and C, as they might be required to supply their 1000 km neighbors.
At the end of the day, I think everyone is starting to understand the ways in which solar and wind are unreliable. The idea that mitigation requires 100% backup can't really be disputed at scale.
Put a different way, as I have said elsewhere, one would have to overbuild solar by an obscene multiplier (some have estimated as much as 70x) to achieve the equivalent of a reliable power source across a wide geographical area.
The UK have a massive solar and wind project bringing them power from Morocco, some 4000 km away. Sounds great...until there's a problem. If the cities using this power don't have 100% reliable backup there will be trouble.
Frankly, it does not help that articles such as this one provide false information that get repeated and becomes widely distributed:
https://www.energy.gov/eere/articles/how-much-power-1-gigawa...
Here, the energy department claims 3.125 million 320 W panels give you 1 GW.
Not even close. First, 320 W panels NEVER make 320 W.
Why?
That rating is at 25° C and ideal lighting conditions. Panels have a negative temperature coefficient. At real operating temperatures they do not output the rated peak output. At actual operating temperatures you will lose 5% to 7% of that. Add other real-life installation factors and 10% is likely a very safe estimate.
That means a 320 W panel will, at best, under ideal condition, produce somewhere in the range of 290 to 300 W peak for a few seconds at the top of the solar day.
That would bring the 3.125 million panel installation down to 938 MW (assuming 300 W peak per panel) for 15 to 30 seconds per day.
Just to deliver a 1 GW peak for a few seconds we have to multiply the number of panels by a factor of almost 7%. That brings the count up to 3.344 million panels.
However, these panels will not produce the equivalent of 1GW of power for 24 hours. If the intent is to get there with solar, we need more panels and lots of batteries.
How many panels?
Well, on a perfect day the power generation curve is an inverted parabola. The integral of that curve over time gives us the energy generated during that period. Doing the math we see that is 66% of the equivalent 12 hour constant power period.
That means we need to multiply the size of the array by 1.5 to collect the equivalent constant power energy over 12 hours. That brings us to 6.688 million panels.
And, yes, lots of batteries are required for this to work.
Next, we need to at least double this to collect energy to supply at night. That gets the count up to 13.376 million 320 W panels. And millions of batteries.
That number is 4.3 times larger than what the energy department mistakenly quotes in the linked article.
And yet this does not stop there. One could (should?) easily double the size of this array yet again to account for weather, dirt and failures. If I round that out to a 10x multiple, we now need 31.25 million panels to supply a steady 1GW day and night while only using solar power.
What remains to be calculated is the massive land use this represents. One cannot just use the size of the panels. Solar installations have a packing factor. The idea is that you need space around the panels for access, maintenance, installation and other needs.
That number seems to be in the order of 10 acres per MW of peak generation:
https://www.nrel.gov/docs/fy13osti/56290.pdf
In the case of this realistic 1GW plant with 31.25 million panels, the land requirement would be about 100K acres. This is about 156 square miles or a square of over 12 miles per side.
As to the amount of backup needed: https://www.nature.com/articles/s41467-021-26355-z
Then consider all the dispatchable loads that decrease the gap even further.
My claim is that solar requires 100% backup.
OK, let's break it down:
Solar Output:
Under ideal conditions, roughly inverted parabolic output
1.00 ┼ ╭────╮
0.90 ┤ ╭─╯ ╰─╮
0.80 ┤ ╭─╯ ╰─╮
0.70 ┤ ╭╯ ╰╮
0.60 ┤ ╭╯ ╰╮
0.50 ┤ │ │
0.40 ┤ ╭╯ ╰╮
0.30 ┤ ╭╯ ╰╮
0.20 ┤ ╭╯ ╰╮
0.10 ┤ │ │
0.00 ┼──────────────╯ ╰─────────
Clouds and weather can cause up to 100% drop in output any time
Rain will drop your peak output practically down to zero all day
Dirt will drop total output by a variable amount until cleaned
1.00 ┼ ╭───╮
0.90 ┤ ╭─╮│ ╰╮
0.80 ┤ ╭─╯ ││ │ ╭╮
0.70 ┤ ╭╯ ││ │ │╰╮
0.60 ┤ ╭╯ ││ │ │ ╰╮
0.50 ┤ │ ││ │ │ │
0.40 ┤ ╭╯ ││ ╰─╯ ╰╮
0.30 ┤ ╭╯ ││ ╰╮
0.20 ┤ ╭╯ ││ ╰╮
0.10 ┤ │ ││ │
0.00 ┼──────────────╯ ╰╯ ╰─────────
Daytime:
You need up to 100% backup to be available at any time.
Night:
To state the obvious, 100% backup is required.
Conclusion:
If you need reliable 100% backup at any point
during 24 hours, this backup capacity has to be
available 24/7/365.
Regarding the link you provided. I am familiar with this article, which, of course, confirms my point.
Figure 5, which is titled "Maps of electricity system reliabilities under the most reliable solar-wind mix without excess generation or energy storage", puts the US at less than 88%.
This means that, ON AVERAGE, 12% of the time you need 100% backup for the most optimal form of solar and wind combined.
I loudly highlighted ON AVERAGE because it is important to understand this is a problem when dealing with statistics. You cannot apply the average of the average of the average to an entire population. This is known as the tyranny of the averages.
Averages are fantastic to wave hands around and talk about generalities. They do not cover my little town of 300K residents going dark for two hours because the solar system powering it had no backup.
The real numbers, once you start to get closer to local realities, are not represented by these average. The real numbers are much worse.
Solar cannot exist without external backup. Solar and wind cannot exist without external backup. That's the real conversation we have to have.
Somehow people read this to mean that I am saying solar and wind are bad and not usable. That is not AT ALL what I am saying. I am simply highlighting that we cannot "go green" just with these technologies. And it gets much, much worse, when we start to throw in hundreds of millions of electric vehicles. My point, in the aggregate, is that we, in the US, desperately need to change our thinking with regards to nuclear. Otherwise we are going to end-up with a bunch of solar and wind backed-up by massive amounts of power being generated by burning stuff.
Try again.
No personal attacks this time.
Where, exactly, did I lie?
Show your work.Then note w2e, hydro and other average-energy-limited dispatchable sources exist. A hydro system which can provide 100MW on average can provide 1GW peak. There are a few tens of GW of waste stream methane available in the US alone. It can be stored and burnt at any time to meet unshiftable demand.
Then note that dispatchable loads such as EV charging exist and exceed non-dispatchable ones. They make VRE easier to use, not harder as you claim.
Then note when pools are pumped, water towers are fied, thermal storage in buildings is charged, zinc refineries and so on are run. It's not done in the middle of the night in regions with thermal generation because people just love noise and graveyard shifts.
If you have 1 watt of constant load, 2 watts (average over 6 months) of dispatchable load, 2 net watts of solar (ie. 4 nameplate watts), long distance transmission, 2 net watts of wind, and 1 net watt of hydro and green fuel burnable in an OCGT, then you have plenty of power.
You're willfully ignoring systems and demand shifting and trying to claim only always-on thermal generation works. This is a lie.
Even assuming fossil fuel for the week a year the system has low output, a VRE dominated grid still cheaper and greener than alternatives and you still don't need to run your electrolysers or zinc refineries or arc furnaces or thermal storage heaters. And if you have a day warning the Al smelters can clear the lines too. This is done all the time in systems dominated by thermal generation to meet demand spikes. Claiming these loads need backup instead of being backup is a lie.
You're trying to pretend turning a fossil fuel generator for the non-dispatchable loads on ever eliminates any gains from the whole system just because it has the same power as the un-shiftable peak demand. This is also a lie.
You're trying to pretend that fixed loads are constant, so a power-limited thermal generator would need no storage or overprovision. This is also a lie.
You're trying to pretend weather events where there is zero wind or sun across a large region for over a day are common. This has never happened. This is a lie.
You're trying to pretend thermal generators never go offline in a correlated way so that any correlated downtime is exclusively VRE. This is a lie.
You're trying to pretend building a system that can eliminate 85-95% of emissions in a year or two for a tenth of the price and then startig on the boondoggle which eliminates 90% of emissions and exports the rest to Niger isn't the obvious and objectively correct answer even if your above lies were accurate.
You continue to resort to insulting me over many threads across many months. Any time there's a thread on a related subject you seem intent in demonstrating your ability to insult me.
I read the article. Of course I did. I read it a couple of years ago, or whenever it was published.
It actually supports my point!
Solar requires the availability reliable power
for up to 100% backup.
I am not saying solar or solar + wind are a bad idea, pointless or that we should not use them. Heck, I have made a non-trivial investment in solar myself. And one of the companies I own actually develops related technologies.
Once again, the very article you posted clearly states that the COMBINATION of solar and power in the US is, at best, ~ 88% reliable. Solar alone? Less so.
I can support my claims with actual data from my own solar array. I just visited a six million dollar installation in Singapore. The results are even worse.
Here in So. Cal, we are about to get hit with yet another large storm. All solar power will be reduced to nothing during this time.
I have no clue what your problem is. You are consistent in the use of insults in place of conversation, math and science. Lots of hand-waving. No substance at all. It's exhausting, really, but I am not going to allow you to bully me into discussing this perspective in the context of facts-based discussions.
If I am wrong, I am more than willing to be shown where, why and how. Always. My life and career has been about learning, constantly. That happens with respect and facts, not insults.
EDIT:
"Shading in each panel represents the 39-year average estimated reliability (% of total annual electricity demand met)"
https://i.imgur.com/9OMK9eZ.png
This shows that 100% solar (without mixing-in wind) in the US only has a reliability (% of demand met) of about 53%.
Solar requires 100% reliable backup.
https://i.imgur.com/ut52ZbI.png
Solar + 12 hours of storage gets up to only 82% reliability (% of demand met). In other words, cities go dark 18% of the time.
Solar requires 100% reliable backup.
Solar requires 100% reliable backup.
Solar requires 100% reliable backup.
The fact that you have to use wind and storage to achieve performance above the 53% of demand achievable by solar alone fully supports the point I have been making:
Solar requires 100% reliable backup.
You're now trying to gaslight by saying you meant the whole system needs redundancy.
You're also somehow claiming that anyone advocating solar is advocating for zero wind. This is another unhinged lie.
Solar requires 100% reliable backup.
Batteries?
That's backup.
Oh, wait. The batteries need backup because they cannot be charged by a solar array that is sized to only fit the load. You need to oversize it. By a lot. In fact, you need to at least double your array size to charge batteries to be used at night.
In other words, backup for the backup.
Wind?
That's backup.
Hydro?
That's backup.
More solar from thousands of miles away where there might still be light?
That's backup.
Nuclear?
That's backup.
Gas/Coal/Fossil?
That's backup.
Oh, wait, here's Elon Musk talking about something you claimed to be a lie, when I said you need to overbuild solar arrays by 7x or more for continuous power. Here he is, less than two weeks ago:
https://www.youtube.com/live/Hl1zEzVUV7w?feature=share&t=121...
You need to 5x for continuous power, he says.
Oops.
It's also great that he mentions solar and wind can coexist. Some of backup can be co-located at some locations. Fantastic.
Please stop resorting to insults. Please? Insulting people does not change the reality around you. It never will.
Do the math and understand what you are talking about. Please.
Nobody is saying solar is bad or impossible to use. This interpretation you seem to prefer is entirely fabricated. My claim that solar requires 100% backup is --quite literally-- as true as day and night and as necessary as what happens with solar between day and night. That you continue to attack and insult me over this is difficult to understand.
BTW, he is not talking about weather effects and only thinking about local semi-ideal conditions. I'm sure that will be covered at some point. The multiple is much higher than 5x.
Note to @dang, if you are reading this, please do not delete this thread.
Hopefully there's a lesson here for others. Treat each other with respect and consideration. Do not react to someone who does not offer you the same. This is their overwhelming objective. To have to descend to their level. Don't do it. Poise in the face of adversity. That's the real proof of a person's character.
This is where you started. Now you're doubling down on the gaslighting,
You were very explicit and batteries or a resilient VRE system with other renewables were notnl what you were talking about.
And you are consistently disrespectful, arrogant and condescending. The only person stupid enough to think the cry bully act will work is you. Thinking that your snide condescention is subtle is not the same as it not being blindingly obvious.
Hmmm. OK.
It's nighttime, my solar array is making zero power right now. Thankfully I have 100% backup from the grid.
Regarding: "Without going too deep: If you need 100% backup for solar, why use solar"
Science and engineering are about always asking questions and challenging assumptions.
Is solar --which requires 100% backup-- better, the best, ideal?
Is it, really?
How about this. Let's use the article you posted to challenge what I've been saying [0]. You know, the one that backfired and actually supported my all my claims so far. Let's use it one more time. Maybe you are right and I am stupid.
Again, table #2.
My question was: Why use solar?
The table shows the "39-year average estimated reliability (% of total annual electricity demand met)".
In other words, what percentage of the time the lights in your town will stay on given a power generation and storage technology mix.
Here's what it says (comments mine):
Without storage ($):
Solar alone: 54% (half the time you go dark)
Wind alone: 82% (wow)
With 3 hours of storage ($$):
Solar alone: 66% (meh)
Wind alone: 85% (nice)
With 12 hours of storage ($$$$$):
Solar alone: 81% (finally)
Wind alone: 88% (better)
Overbuilt by 1.5x with just 3 hours of storage ($$$$):
Solar alone: 70% (meh)
Wind alone: 95% (double-wow)
If we just add 3 hours of storage, wind goes up a few percent, same for solar. Not too exciting.
The real find is what happens if we overbuild generation capacity by 1.5x and add just 3 hours of storage:
Wind goes up to 95% reliability, while solar only 70%.
95% RELIABILITY FOR WIND!
70% RELIABILITY FOR SOLAR!
That is a massive find, one deserving saying it out loud.
The city is dark only 5% of the time with wind, vs. 30% with solar.
Both require backup for the percentage they cannot deliver reliably. Wind requires massively less backup.
Is wind cheaper, simpler, easier to maintain over the long term? Not sure, I would have to do the math on that. The questions are compelling enough for me to explore further.
There's another element that is often not explored: Solar requires almost 100% reliance on China for the entire supply chain. Does wind technology inshore most of the supply chain? The world today is a nasty place. If the US, Europe and other regions can inshore manufacturing and technology, rather than send trillions of dollars to China, this would be a good thing, something worth pursuing.
So, again, I ask:
Given the above. Why use solar?
Your article, once again, supports my perspective.
> you are consistently disrespectful, arrogant and condescending.
You are confusing those things with stating what I know because I am sure of it. There is a difference. A professor isn't disrespectful, arrogant and condescending because she asserts what she knows to be true. Neither is a doctor, lawyer or, for that matter, an engineer.
I urge you to, once again, stop the insults, fire-up Excel and do some math before posting. I just used the numbers you provided to show that questioning solar as the best option likely has merit.
Open for discussion? Of course. Get to the point where you have done enough work to have a reasonable understanding of the subject matter. Then, use numbers. Not insults. Anyone would gladly have a conversation with you under those condition.
None of this means solar is useless and should not continue to scale. It does mean we really need to be objective and check our assumptions at the door. My guess is that, yes, of course solar is worthwhile and valuable. Yet, no, it is unlikely to be the best solution for everything. It needs backup, lots of it. It needs wind. Lots of it. And it probably needs fossil and nuclear generation to be able to deliver constant, consistent and reliable power.
Nobody is likely to install wind turbines atop their homes, so, yes, definitely, solar has a place, likely on our roofs. I would question solar at scale because wind looks to be massively better on first inspection. This needs a further look at the numbers and reality of wind.
I am being very patient here and trying to teach you a few things anyone would find valuable.
First, there's the matter of treating others with respect and learning to have a conversation. We all benefit from this.
Second, we have to be careful about our assumptions. We should not dismiss others because we don't like what they are saying. Above all, before aggressively challenging anyone, we have to do the work --which can be difficult and time consuming.
You have to keep in mind that someone with the scientific training who is presenting arguments based on math and physics like has devoted a non-trivial amount of time to understanding the problem. One cannot challenge someone coming from that perspective without doing the work first.
Third, don't take this discussion personally. I am simply trying to guide you into understanding that your approach isn't constructive and does not lead discovering the truth through dialogue.
Anyone can be wrong and anyone can be right. I've been in both those corners. Yet, we are never going to discover where we are if we decide to just slap each other silly. That's the opposite of constructive.
I notice you've backed off even further from your claims of needing 1200GW of inflexible thermal generation that isn't even useful for peaking (not that this will stop you from posting them again).
Here's yet another example in the comment chain:
> Sure, you did the math for local solar only.
> But if you add in existing hydro + nuclear, a good proportion of wind (which is more consistent and stronger at night), some good long distance interconnects, and a modicum of storage, the number comes out a lot smaller.
> Here's the math: https://mitpress.mit.edu/9780262545044/electrify/
> It comes up with a 20% overbuild.
Yet another example of someone pointing out your straw man. Then you arrogantly insulting them.
Everyone you're talking down to has either done the math, or read journals by competent people who have.
Wow.
I can't imagine what aspect of your life drives you to behave in this manner.
Please stop chasing me around HN to insult me. OK? You can disagree with me all you want. Just stop with this troublesome behavior. It isn't healthy.
This conversation is over.
You don't understand that you can have a mix of power generation whilst claiming that everyone else is stupid and ignorant. Or you're intentionally lying.
Neither is worthy of respect or of treating you better than you treat others.