4 ms·

Good longread. What I'd like to have a better understanding of, and I'm hoping to crowdsource here, is exactly how the solar panel cost has come down so precip

by pjc50 2y ago

Good longread. What I'd like to have a better understanding of, and I'm hoping to crowdsource here, is exactly how the solar panel cost has come down so precipitously. Part of it is simply manufacture scaling - almost everything is much cheaper in large quantities. But part of it must be a thousand incremental tech advances. Things like the reduced kerf diamond wire saw. Also of note: I think monocrystalline has won completely? People experimented with all sorts of alternate chemistries and technologies, like ion deposition and the extremely poisonous CIGS, but good old "Czochralski process + slice thinly" has won despite being energy intensive itself. Perovskites remain an unknown quantity.

pfdietz 2y ago
CdTe is still out there, from First Solar, but it's not much of the market (and has scalability problems due to the need for tellurium, even if the active layer is much thinner than in silicon cells.) One little advance that swept the industry a couple of years ago was replacement of boron as a dopant by gallium. Boron doped silicon has light induced degradation, which was determined to cause a small loss in efficiency due to formation of boron trapping centers under prolonged light exposure. Gallium-doped silicon doesn't have this problem.
wolfram74 2y ago
You're in luck! The author's earlier piece on the subject attempts to address that exact question. Learning curve effects and piggy backing off the computer chip industry are major factors if I recall, but I haven't reread the piece in a while. https://www.construction-physics.com/p/how-did-solar-power-get-cheap-part https://www.construction-physics.com/p/how-did-solar-power-g...
doctoboggan 2y ago
My understanding is that China recognized the potential of solar power around 20 years ago and decided they wanted to be the world's manufacturing hub for solar panels. The government invested in R&D early, and today we are reaping the fruits of that investment. The same thing is happening now with storage, but western governments are weary of losing that battle as well. To address this massive tariffs were put in place by the previous US administration, and are likely to be increased by the current administration. Hopefully this doesn't slow down the production of batteries, but instead just moves the production out of China and into other countries, but that remains to be seen.
- cman1444 2y ago
  Wary not weary
- tim333 2y ago
  The US policy doesn't seem very smart. invest in R&D -> reap fruit tariff barriers -> inefficient industries The current administration seems to be doubling down on that.
philipkglass 2y ago
The article posted by wolfram74 is part one of two, covering solar PV history up through the early 1980s. Here's part two of the series with more recent history: https://www.construction-physics.com/p/how-did-solar-power-get-cheap-part-28a https://www.construction-physics.com/p/how-did-solar-power-g... Even this fairly long two-part discussion misses some of the more important technical developments of the past 20 years. Converting trichlorosilane to pure silicon via CVD growth in Siemens-type reactors is now much more energy efficient due to changes in rod geometry and heat trapping via reactor design. A significant minority of purified silicon is now manufactured via even more efficient fluidized bed reactors. The solar industry is dominated by Czochralski process monocrystalline silicon, but it's now continuous Czochralski: multiple crystals grown from a single crucible, recharging the molten silicon over time; the traditional process used a crucible once and then discarded it. The dominant silicon material has switched from boron doped p-type silicon to gallium doped p-type silicon (mentioned by pfdietz) to phosphorus doped n-type silicon (used by the currently dominant TOPCon cell technology as well as heterojunction (HJT) cells and most back contact cells). Changes in wafering that you mentioned (like the reduced kerf diamond wire saw) have reduced silicon consumption per wafer and therefore per watt, even holding cell technology constant. The dominant cell technology has moved from Al-BSF to PERC to mono-PERC to TOPCon. Heterojunction and back-contact cells are not yet dominant, but they are manufactured on a multi-gigawatt scale and will probably overtake TOPCon eventually. Each one of these changes has eked out more light conversion efficiency from the same area of silicon. Cells mostly still use screen-printed contacts made from conductive silver pastes, much like 20 years ago, but there has been continuous evolution of the geometry and composition of applied pastes so that silver consumption per watt is now much lower than it used to be. This is important because silver has the highest cost per kilogram of any material in a typical solar panel, and it's the bottleneck material for plans to expand manufacturing past the terawatt scale. Wafer, cell, and module manufacturing have become much more automated. That reduced labor costs, increased throughput, and increased uniformity.
- justanotherjoe 2y ago
  In terms of resource extraction needed for the batteries and the panels, how sustainable is it? The way I understand it is that you can't really repair broken panels and batteries... Can we still make these after, let's say, 500 years? I have no conception at all in this topic...

by pjc50 2y ago

pfdietz 2y ago

CdTe is still out there, from First Solar, but it's not much of the market (and has scalability problems due to the need for tellurium, even if the active layer is much thinner than in silicon cells.) One little advance that swept the industry a couple of years ago was replacement of boron as a dopant by gallium. Boron doped silicon has light induced degradation, which was determined to cause a small loss in efficiency due to formation of boron trapping centers under prolonged light exposure. Gallium-doped silicon doesn't have this problem.

wolfram74 2y ago

You're in luck! The author's earlier piece on the subject attempts to address that exact question. Learning curve effects and piggy backing off the computer chip industry are major factors if I recall, but I haven't reread the piece in a while. https://www.construction-physics.com/p/how-did-solar-power-get-cheap-part https://www.construction-physics.com/p/how-did-solar-power-g...

doctoboggan 2y ago

My understanding is that China recognized the potential of solar power around 20 years ago and decided they wanted to be the world's manufacturing hub for solar panels. The government invested in R&D early, and today we are reaping the fruits of that investment. The same thing is happening now with storage, but western governments are weary of losing that battle as well. To address this massive tariffs were put in place by the previous US administration, and are likely to be increased by the current administration. Hopefully this doesn't slow down the production of batteries, but instead just moves the production out of China and into other countries, but that remains to be seen.

cman1444 2y ago
Wary not weary
tim333 2y ago
The US policy doesn't seem very smart. invest in R&D -> reap fruit tariff barriers -> inefficient industries The current administration seems to be doubling down on that.

philipkglass 2y ago

The article posted by wolfram74 is part one of two, covering solar PV history up through the early 1980s. Here's part two of the series with more recent history: https://www.construction-physics.com/p/how-did-solar-power-get-cheap-part-28a https://www.construction-physics.com/p/how-did-solar-power-g... Even this fairly long two-part discussion misses some of the more important technical developments of the past 20 years. Converting trichlorosilane to pure silicon via CVD growth in Siemens-type reactors is now much more energy efficient due to changes in rod geometry and heat trapping via reactor design. A significant minority of purified silicon is now manufactured via even more efficient fluidized bed reactors. The solar industry is dominated by Czochralski process monocrystalline silicon, but it's now continuous Czochralski: multiple crystals grown from a single crucible, recharging the molten silicon over time; the traditional process used a crucible once and then discarded it. The dominant silicon material has switched from boron doped p-type silicon to gallium doped p-type silicon (mentioned by pfdietz) to phosphorus doped n-type silicon (used by the currently dominant TOPCon cell technology as well as heterojunction (HJT) cells and most back contact cells). Changes in wafering that you mentioned (like the reduced kerf diamond wire saw) have reduced silicon consumption per wafer and therefore per watt, even holding cell technology constant. The dominant cell technology has moved from Al-BSF to PERC to mono-PERC to TOPCon. Heterojunction and back-contact cells are not yet dominant, but they are manufactured on a multi-gigawatt scale and will probably overtake TOPCon eventually. Each one of these changes has eked out more light conversion efficiency from the same area of silicon. Cells mostly still use screen-printed contacts made from conductive silver pastes, much like 20 years ago, but there has been continuous evolution of the geometry and composition of applied pastes so that silver consumption per watt is now much lower than it used to be. This is important because silver has the highest cost per kilogram of any material in a typical solar panel, and it's the bottleneck material for plans to expand manufacturing past the terawatt scale. Wafer, cell, and module manufacturing have become much more automated. That reduced labor costs, increased throughput, and increased uniformity.

justanotherjoe 2y ago
In terms of resource extraction needed for the batteries and the panels, how sustainable is it? The way I understand it is that you can't really repair broken panels and batteries... Can we still make these after, let's say, 500 years? I have no conception at all in this topic...