5 ms·

If you do the math without your thumb on the scale you get a different answer. Everybody knows rooftop solar costs several times utility-scale solar. If you get

by ncmncm 4y ago

If you do the math without your thumb on the scale you get a different answer. Everybody knows rooftop solar costs several times utility-scale solar. If you get only 14% duty cycle, you are doing worse than most. Ask the people in Georgia and South Carolina how much value they got for the $15B they were made to spend on their 0W nuke plant.

robomartin 4y ago
> Everybody knows rooftop solar costs several times utility-scale solar Nope. Not true. The fact that contractors are raping people doesn't mean that's the cost. The system I installed for about $30K was quoted at $100K. If people pay stupid money for solar that's their problem. > If you get only 14% duty cycle, you are doing worse than most. Not sure where that number comes from. Oh, wait, that's 1/7 th. Ah, you are using my 7x figure to attack my argument? Show me the math that compares any solar system to a nuclear power generator. See, the fact that you used this 14% figure confirmed my suspicion. You really don't know what you are talking about. For all I know you have the mathematical skills to do the numbers, you just haven't taken the time to do it and, as a result, are operating under ideas that can only be described as part of a cult rather than science and engineering. > Ask the people in Georgia and South Carolina how much value they got for the $15B they spend on their 0W nuke plant. By that logic aircraft should not have been developed, ever. If a few failures means a technology is to be avoided most of what we enjoy today would not exist. You are intentionally avoiding the mathematical realities of solar by using a project that was grotesquely mismanaged to sidestep reality. Google says there are 440 nuclear reactors in the world. One or two failed projects due to abject incompetence clearly isn't an argument at all in support of anything other than, don't hire idiots. Do you even know the answer? If I asked you to describe top level requirements for a photovoltaic array that would be the equivalent of a 1 GW nuclear power plant. What would you say? Do you have any idea at all? Can you describe the calculations? Probably not. Most people don't. They like to argue, sometimes passionately, and yet few actually know what they are talking about. So what's your answer? The photovoltaic equivalent of a 1 GW nuclear power plant is calculated as follows: ... I'll wait.
- quickthrower2 4y ago
  I am interested in the 7 factor. (I have no agenda in this argument). I assume it is because you need to store most of the energy for times when it is not generated, and that storage is not 100% efficient, plus cloudy days and suchlike. You are aiming to not just merely generate the same energy per year as the nuke, but guarantee 1GW at all times. To be a base load?
  - robomartin 4y ago
    Now, this is how a good discussion can be had. Not diverting into irrelevant crap but actually asking the commenter to justify the claim --something I will gladly do here. NOTE: Breaking this into parts because of post limits. ---------------- Power and Energy ---------------- First things first, we have to be careful not to mix energy with power. We all do it out of convenience, yet they are very different things. The differences also affect system-wide technology and economics. Since I can't assume the audience is entirely technical, here's a reasonable analogy for power and energy: Your garden hose is a low power source of water when compared to a firehose. Anyone understands that a firehose can deliver a lot more water per second than a garden hose. Energy is like the amount of water you need to fill-up a swimming pool. You can fill it up with a garden hose, but it could take days. If you use a high power fire hose you might be able to fill up the same swimming pool in seconds. The water distribution infrastructure currently installed in any city is designes such that every home (or a reasonable number of homes) can use their garden hoses and they will all have acceptable flow rates. If every home in a city was specified to have a fire hose, the size and scale of the water distribution systems would be absolutely massive when compared to what we have today. One way to think of this is that power determines how quickly you can deliver energy. Water flow rate determines how quickly you can fill-up your swimming pool. ---------------- The Solar Panel ---------------- What are the realities of a solar panel? Sure, you buy a 325 W panel. Great. How does that behave in the real world, in the context of a system? There are several variables that affect the output of a solar panel: - Mounting angle - Variation of solar radiation based on time of day - Weather (clouds, rain, etc.) - Dirt - Negative temperature coefficient - Wiring losses - Energy conversion losses - Degradation over time I could write pages on the above. I'll limit myself to a couple of elements that have the most impact on power production. ---------------- The Solar Parabola ---------------- If you look at the output of a fixed solar array, regardless of scale, rooftop or megawatt, it will look like an inverted parabola. Here's a picture of that from my 13 kW array: https://i.imgur.com/Fl8ARJd.png https://i.imgur.com/Fl8ARJd.png This is from March of this year. It should be noted that it never reached 13 kW, it peaked at about 10 kW. This is important, but I'll skip over it for now. A nuclear power plant, over the same period of time, would produce constant power for 24 hours. If we are going to scale it down to this graph, we would get 10 kW every second of the day for the full 24 hours. The first thing we need to calculate, then, is the ratio between full power for the solar period vs. what the equivalent nuclear source would deliver. The way you calculate this is to integrate the curves over the period of interest, say from 8 AM to 8 PM. You are comparing the area of a rectangle to that of the parabola that fits within it. The answer to this is surprisingly simple: The ratio is 2/3. In other words, a solar system --of any scale-- rated at the same peak power as a nuclear power plant, will, at best, produce 2/3 (66%) the energy over the same period of time under --and this is important-- ideal conditions. Just using this number, we can calculate that we need to build a 1.5 GW solar array in order to match the daylight energy output of a 1 GW nuclear power plant. ---------------- Power at Night ---------------- That covers you for 12 hours. What do we do for the other half of the day? Batteries, of course. Well, we need extra energy to pump into the batteries so we can use it at night. The 1.5 GW is used-up. If we keep that math simple, that means we need to double our power production capacity. Now we are up to a 3 GW peak power solar system in order to be able to match the energy output of a 1 GW nuclear power plant. I won't cover the cost, scale and realities of such a massive energy storage installation at this time, just remember this is very much a part of the reality of solar --and a very significant one at that. ---------------- Conversion Efficiency ---------------- What I will talk about is the fact that solar arrays require the power conversion systems in order to move energy in and out of batteries and even out to the grid. Current battery charging technologies are nearly 100% efficient, so I'll ignore the small losses incurred going in and out of a battery and over time (self discharge). In order to get in and out of the buildings full of battery packs you will need to use conversion equipment. This will cost about 20% of the energy you produce. Yes, 20% of what you produce will be converted into heat. At the peak of 3 GW, we would be producing 0.6 GW in heat. That's no joke. That's nearly the peak output of a nuclear facility being used to create heat. I won't get into what this might mean in terms of having to provide for cooling. I don't know how this is handled at such massive scales. I just know that 0.6 GW of heat producing power is a very serious number. OK, this means that our system now needs to be upsized yet again in order to compensate for the 20% conversion loss. 3 GW * (1/0.8) = 3.75 GW That's where we are: Without considering other factors, the solar equivalent of a 1 GW nuclear power plant requires 3.75 GW peak power and a train-load of batteries. Are we done? No, not even close.

by ncmncm 4y ago

robomartin 4y ago

> Everybody knows rooftop solar costs several times utility-scale solar Nope. Not true. The fact that contractors are raping people doesn't mean that's the cost. The system I installed for about $30K was quoted at $100K. If people pay stupid money for solar that's their problem. > If you get only 14% duty cycle, you are doing worse than most. Not sure where that number comes from. Oh, wait, that's 1/7 th. Ah, you are using my 7x figure to attack my argument? Show me the math that compares any solar system to a nuclear power generator. See, the fact that you used this 14% figure confirmed my suspicion. You really don't know what you are talking about. For all I know you have the mathematical skills to do the numbers, you just haven't taken the time to do it and, as a result, are operating under ideas that can only be described as part of a cult rather than science and engineering. > Ask the people in Georgia and South Carolina how much value they got for the $15B they spend on their 0W nuke plant. By that logic aircraft should not have been developed, ever. If a few failures means a technology is to be avoided most of what we enjoy today would not exist. You are intentionally avoiding the mathematical realities of solar by using a project that was grotesquely mismanaged to sidestep reality. Google says there are 440 nuclear reactors in the world. One or two failed projects due to abject incompetence clearly isn't an argument at all in support of anything other than, don't hire idiots. Do you even know the answer? If I asked you to describe top level requirements for a photovoltaic array that would be the equivalent of a 1 GW nuclear power plant. What would you say? Do you have any idea at all? Can you describe the calculations? Probably not. Most people don't. They like to argue, sometimes passionately, and yet few actually know what they are talking about. So what's your answer? The photovoltaic equivalent of a 1 GW nuclear power plant is calculated as follows: ... I'll wait.

quickthrower2 4y ago
I am interested in the 7 factor. (I have no agenda in this argument). I assume it is because you need to store most of the energy for times when it is not generated, and that storage is not 100% efficient, plus cloudy days and suchlike. You are aiming to not just merely generate the same energy per year as the nuke, but guarantee 1GW at all times. To be a base load?
- robomartin 4y ago
  Now, this is how a good discussion can be had. Not diverting into irrelevant crap but actually asking the commenter to justify the claim --something I will gladly do here. NOTE: Breaking this into parts because of post limits. ---------------- Power and Energy ---------------- First things first, we have to be careful not to mix energy with power. We all do it out of convenience, yet they are very different things. The differences also affect system-wide technology and economics. Since I can't assume the audience is entirely technical, here's a reasonable analogy for power and energy: Your garden hose is a low power source of water when compared to a firehose. Anyone understands that a firehose can deliver a lot more water per second than a garden hose. Energy is like the amount of water you need to fill-up a swimming pool. You can fill it up with a garden hose, but it could take days. If you use a high power fire hose you might be able to fill up the same swimming pool in seconds. The water distribution infrastructure currently installed in any city is designes such that every home (or a reasonable number of homes) can use their garden hoses and they will all have acceptable flow rates. If every home in a city was specified to have a fire hose, the size and scale of the water distribution systems would be absolutely massive when compared to what we have today. One way to think of this is that power determines how quickly you can deliver energy. Water flow rate determines how quickly you can fill-up your swimming pool. ---------------- The Solar Panel ---------------- What are the realities of a solar panel? Sure, you buy a 325 W panel. Great. How does that behave in the real world, in the context of a system? There are several variables that affect the output of a solar panel: - Mounting angle - Variation of solar radiation based on time of day - Weather (clouds, rain, etc.) - Dirt - Negative temperature coefficient - Wiring losses - Energy conversion losses - Degradation over time I could write pages on the above. I'll limit myself to a couple of elements that have the most impact on power production. ---------------- The Solar Parabola ---------------- If you look at the output of a fixed solar array, regardless of scale, rooftop or megawatt, it will look like an inverted parabola. Here's a picture of that from my 13 kW array: https://i.imgur.com/Fl8ARJd.png https://i.imgur.com/Fl8ARJd.png This is from March of this year. It should be noted that it never reached 13 kW, it peaked at about 10 kW. This is important, but I'll skip over it for now. A nuclear power plant, over the same period of time, would produce constant power for 24 hours. If we are going to scale it down to this graph, we would get 10 kW every second of the day for the full 24 hours. The first thing we need to calculate, then, is the ratio between full power for the solar period vs. what the equivalent nuclear source would deliver. The way you calculate this is to integrate the curves over the period of interest, say from 8 AM to 8 PM. You are comparing the area of a rectangle to that of the parabola that fits within it. The answer to this is surprisingly simple: The ratio is 2/3. In other words, a solar system --of any scale-- rated at the same peak power as a nuclear power plant, will, at best, produce 2/3 (66%) the energy over the same period of time under --and this is important-- ideal conditions. Just using this number, we can calculate that we need to build a 1.5 GW solar array in order to match the daylight energy output of a 1 GW nuclear power plant. ---------------- Power at Night ---------------- That covers you for 12 hours. What do we do for the other half of the day? Batteries, of course. Well, we need extra energy to pump into the batteries so we can use it at night. The 1.5 GW is used-up. If we keep that math simple, that means we need to double our power production capacity. Now we are up to a 3 GW peak power solar system in order to be able to match the energy output of a 1 GW nuclear power plant. I won't cover the cost, scale and realities of such a massive energy storage installation at this time, just remember this is very much a part of the reality of solar --and a very significant one at that. ---------------- Conversion Efficiency ---------------- What I will talk about is the fact that solar arrays require the power conversion systems in order to move energy in and out of batteries and even out to the grid. Current battery charging technologies are nearly 100% efficient, so I'll ignore the small losses incurred going in and out of a battery and over time (self discharge). In order to get in and out of the buildings full of battery packs you will need to use conversion equipment. This will cost about 20% of the energy you produce. Yes, 20% of what you produce will be converted into heat. At the peak of 3 GW, we would be producing 0.6 GW in heat. That's no joke. That's nearly the peak output of a nuclear facility being used to create heat. I won't get into what this might mean in terms of having to provide for cooling. I don't know how this is handled at such massive scales. I just know that 0.6 GW of heat producing power is a very serious number. OK, this means that our system now needs to be upsized yet again in order to compensate for the 20% conversion loss. 3 GW * (1/0.8) = 3.75 GW That's where we are: Without considering other factors, the solar equivalent of a 1 GW nuclear power plant requires 3.75 GW peak power and a train-load of batteries. Are we done? No, not even close.