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Part 2: ---------------- Unreliable Solar Production ---------------- https://i.imgur.com/SOr30bX.png https://i.imgur.com/SOr30bX.png Take a look at that ima
by robomartin 4y ago
Part 2:
---------------- Unreliable Solar Production ----------------
https://i.imgur.com/SOr30bX.png https://i.imgur.com/SOr30bX.png
Take a look at that image. That, again, is from my solar array in March of this year. What happened to the nice smooth parabola? Well, the weather happened, that's what you are looking at. Each one of those horrific dips is a cloud or set of clouds calmly flying by. Yup. Here's the graph for another day around the same time period:
https://i.imgur.com/yvTdNX0.png https://i.imgur.com/yvTdNX0.png
You can see just how dramatic the power loss can be just because of a few clouds flying by. In one case there's a drop from 7.5 kW to about 2.5 kW. In another a drop from 8 kW to 4 kW. And these drops last HOURS.
The net effect is that the peak rating of your solar array is a distant image in the context of real-world solar. My 13 kW array gets taken down to 2.5 kW by a CLOUD.
What this means, at a practical level, is that, in order to have the ability to deliver constant power --like a nuclear power plant-- 24/7 your solar system will have to be overbuilt to a larger scale yet. More batteries, lots more, and lots more solar panels.
Imagine a city or small town suffering such deep power losses as weather rolls over the one-and-only solar facility. Rain would do the same thing, even worse.
How do we even begin to calculate something like this?
Well, let's look at an example of day to day energy generation for my system.
This is January of this year:
https://i.imgur.com/bGuCH2F.png https://i.imgur.com/bGuCH2F.png
Here's last month:
https://i.imgur.com/8lYKImD.png https://i.imgur.com/8lYKImD.png
We have days with less than half the energy output, yes, here in sunny California. I don't even want to imagine what this might look like in other parts of the country/world where they have real weather. Imagine this happening at the scale of a city.
In checking the daily output of this system over the last 24 months, I estimate that 7 out of 31 days we are producing at half the rated peak power, if not less. This represents an 11.3% loss of capacity, which we have to compensate for by building a larger system yet.
Now we need a 4.2 GW system to match the output of a 1 GW nuclear power plant.
Does it end there?
Nope.
---------------- Negative Temperature Coefficient and The Seasons ----------------
https://i.imgur.com/EF2L3Hk.png https://i.imgur.com/EF2L3Hk.png
That's month-to-month generation for all of last year. You can see that the peak was reached in May, not in the middle of summer as most would think.
Why?
Solar panels have a characteristic called "Negative Temperature Coefficient". In plain language, it means that they produce less power when they get hot. In the summer, for example. Couple that to variations of solar radiation based on the season and you get the above graph.
The difference between the May peak and December low is about a 50% reduction in energy production yet again. This seems to be a common theme, doesn't it?
If the design was based on May peak power generation as a constant throughout the year, we now need to compensate for the 22% loss suffered due to seasons and the negative temperature coefficient of the panels.
This brings our 4.2 GW array up to 5.5 GW. Again, to match the output of a 1 GW nuclear power plant.
It should not be lost in this discussion that this also represents a massive increase in the number of batteries you'll need, heat management as well as the massive amounts of construction materials, labor and land such a system would require.
I'll stop here because the rest of the analysis starts to get into deeper technical details an modeling that is hard to convey in this medium. Things like the loss of energy in the very wires used to connect everything together and the statistical failures of a system in the with somewhere in the order of 16 million solar panels (that's roughly what you need for a 5+ GW system.
The final number quickly approaches 7 GW as the solar equivalent of a 1 GW nuclear power plant. You also need somewhere over 20,000 or 30,000 acres of land for this installation. No telling what the ecological effect of such a monster might be. The US Department of Energy says that the solar equivalent of a 1 GW nuclear power plant needs 75 times more land. Quoting:
“A typical 1,000-megawatt nuclear facility in the United States needs a little more than 1 square mile to operate. NEI says wind farms require 360 times more land area to produce the same amount of electricity and solar photovoltaic plants require 75 times more space.”
https://www.energy.gov/sites/prod/files/2019/01/f58/Ultimate%20Fast%20Facts%20Guide-PRINT.pdf https://www.energy.gov/sites/prod/files/2019/01/f58/Ultimate...
1 square mile would be covered with roughly 1.3 million solar panels (each being two square meters).
A solar farm requires access isles for installation, cleaning and maintenance of rows of panels. So, out of the 75 square miles the DoE provides as an equivalent, we would have to assume a percentage would have no panels. Here are the results:
33% covered with panels = 30.9375 million panels
50% covered with panels = 46.875 million panels
75% covered with panels = 70.3125 million panels
Assuming 325 W panels:
33% case: 10.1 GW
50% case: 15.2 GW
75% case: 22.9 GW
And so, the best case presented by the US Department of Energy as the solar equivalent of a 1 GW nuclear facility requires 10.1 GW of peak power generation capacity. This aligns very well with my "at least 7x" calculation.
That's my point.
It's math and physics. Very basic math and physics at that. And yet most people are living in a delusional cult that looks at solar as this bubble gum and pink unicorns technology that will save the world. Well, based on the science, I beg to differ. Time to actually discuss facts rather than fantasy.
- ncmncm 4y agoYou can go down any rabbit hole you like, calculating like mad. But if what you are calculating does not match what people have built, are building, or would build, it amounts to preening.
- robomartin 4y agoThanks for the insult. Typical. Since you can't discuss the physics-driven models you have to resort to diverting the conversation or attacking the messenger. Good luck buddy. Live long and prosper.
- ncmncm 4y agoLook, I happily concede that, if we take all your assumptions as given, and all your value judgments as to what is important, the numbers come out just as you say. But checking the map just seems like an essential step before we plunge headlong into the jungle.
- robomartin 4y agoI am saying: "It will take twice as much to fill up the gas tank because I know how to calculate the volume of a container. Here's the math." You are waving your hands around and saying: "No we can fill it up with half the gasoline you just don't believe. And, no, I can't be bothered to do any math or talk about the science of how one calculates the volume of a container. And, BTW, here's a downvote for you!" So, yeah, there really isn't much I can talk about with you. My life is math, science and engineering. I don't do hand-waving. Sorry.
- ncmncm 4y agoCalculating the wrong thing can lead you equally as far astray as doing your calculations wrong. I, also, am an engineer. I take care to set up the right problem.