5 ms·

Floating solar panels that track the Sun

42 points by hhs 4y ago

nico_h 4y ago
that's cool and all, but if they are already anchored, why not have winches that drag one side more than the other to position the arrays towards the sun, instead of propellers which I assume you would have to run continuously? or did I miss-read something?
- pencilguin 4y ago
  People always seem to jump to the the most complicated and expensive design alternatives. A central pivot and a loop of rope around a motor capstan on-shore to gradually rotate the whole array would be obviously simpler and cheaper. The extreme for preferring absurd complication seems especially to show up in attempts at extracting wave energy. So, wave energy startups almost always fail; not because the energy is insufficient or hard to extract, but just because they seem compelled to field doomed, overpriced, expensive, and fragile designs. I sometimes wonder if you need to have foolishly complicated tech to impress investors, who would be disinclined to fund what they feel like they could understand. Generally, if you are putting stuff out in the water, apparatus that might need servicing should be onshore, with the simplest possible connection out to stuff in the water. For wave energy collection, make your collectors suck air out of a big, shared pipe from shore, with a turbine in the inlet onshore. You don't want your expensive, fragile turbine attacked by salt water and crashing waves, and you don't want lots of little ones where one big, shared one does better. Apparatus to collect wave energy should be always under the surface, away from crashing surface waves.
swader999 4y ago
Obvious but of course I never thought off it.
lbriner 4y ago
Kind of curious but I think people can get side-tracked by the idea of "scale". The thought that if something doesn't scale in the traditional way to a few very large installations, it won't work. Consider things like battery storage for the grid etc. and you might think it is a dead horse. However, what if every house had solar panels and a relatively small number of cells with a grid-tie unit. I no longer need to store an enormous amount of energy, just enough for perhaps a few hours of demand for my house. You get to soak up most of the high-sun days into batteries, you can also feed each other a little if someone is using a fair bit more energy along existing small cables. You can then feed in a much smaller number of larger power plants who can make up any remaining peaks and troughs. Don't need to store 1TW of power into a grid-scale plant, just 20M 10KW systems distributed round the entire country. Don't need to point the panels at the sun all day then!
- zdragnar 4y ago
  It's really location-dependent. The upper midwest US can go weeks without direct sunshine or much wind in late December through the first week of February. Batteries fed by solar simply won't suffice- even on sunny days, there are fewer hours of sun. To reduce the number of power plants in the area, we'd need to import electricity from elsewhere, at which point you need to overprovision some geographies and run significant amounts of HVDC lines across the country. Neither of these are free or without their own impacts. Whether that would be better than fission or waiting for fusion or continuing with natural gas is debatable- steel and aluminum are not entirely coal free yet either, nor is the concrete or any of the construction work. OTOH, very sunny areas like the southwest could do quite well here.
  - WaitWaitWha 4y ago
    > OTOH, very sunny areas like the southwest could do quite well here. from the article: > Locations must be chosen carefully to avoid tidal forces and stormy weather from destroying the panels as well as their mooring and anchoring systems. That sort of removes anywhere we have hurricanes, tropical cyclones, typhoons and such; mostly where we have ample sun. That said, it does look interesting. Maybe if they have some more built-in self protection from weather?
    - zdragnar 4y ago
      Anything in a climate that could freeze would require heating elements much like windmills currently do. Unfortunately, windmills don't accumulate ice very quickly, compared to a floating solar panel would in say Lake Superior in winter. I imagine that hurricanes would also rule out much of the east coast and gulf of mexico, leaving... California and Hawaii?
  - kibwen 4y ago
    In this specific example, the Midwest is ideal for wind farms: https://www.eia.gov/energyexplained/wind/where-wind-power-is-harnessed.php https://www.eia.gov/energyexplained/wind/where-wind-power-is... . Wind is already the majority of the energy generated in Iowa: https://en.m.wikipedia.org/wiki/Wind_power_in_Iowa https://en.m.wikipedia.org/wiki/Wind_power_in_Iowa So as far as being location-dependent, indeed it is, though that doesn't preclude other renewable solutions.
zucked 4y ago
The article mentions that the water helps regulate the solar array temperature, ostensibly because the water is used as a heat sink. Does the thermal equation even out such that the body of water temperature is not dramatically impacted? Example: If the solar panels are absorbing sunlight before it can reach the water, the water would be colder. But, if the solar panels are using the water as a heat sink/cooler, the water temp could be brought up in temperature. And what about the blockage of the light? That will inhibit growth of algae and plants underwater. I can see how this might be super useful for man-made bodies of water (for drinking, runoff, etc) but it seems it might be a bit impactful on natural bodies of water.
- ZeroGravitas 4y ago
  Blockage of the light can be a positive. Some locations use floating black plastic spheres to achieve this goal.
  - euroderf 4y ago
    Wouldn't floating white spheres make more sense ? If the goal is to avoid overly warm mater.
    - weberer 4y ago
      White would reflect more, but also allow light to pass through. The goal of these are to completely block light to prevent algae growth.
    - Tyrannosaur 4y ago
      https://youtu.be/uxPdPpi5W4o?t=403 https://youtu.be/uxPdPpi5W4o?t=403 Veritasium video about Los Angeles' reservoir black spheres project. They used black because - The goal was light-blocking more than anything else; black worked best - The black pigment held up to the environment (especially UV degradation) better than anything else they tried I expect the second point was the most important thing. Black plastic is very stable.
  - zucked 4y ago
0cf8612b2e1e 4y ago
Conceptually, I think floating solar could be more efficient, but it strikes me as having significantly higher installation and operational expenses vs ground. If you have nowhere else to install, sure, but I’m long odds that this is cost effective vs more panels installed (more cheaply) on the shore.
- pencilguin 4y ago
  Alternatively, floating PV could be a lot cheaper than installing solid mounting hardware to hold panels off the ground and kept from blowing away in wind that gets under them.
deleted 4y ago
[deleted]
didgetmaster 4y ago
I have often wondered why rooftop solar does not have some kind of tilting system to aim the panel at the sun more without an expensive and sophisticated tracking system. You could mount each panel on a swivel that has a spring on one side and a screw drive on the other side. At night when no power is being generated, the spring causes the panel to automatically move so it is pointing at a slight angle (e.g. 15 degrees) to the east. When the sun comes up in the morning and the panel starts generating power, it also activates a very small motor that turns the screw every few minutes to begin a slow tilt toward the west. This continues all day until the sun goes down and the process resets.
- cedilla 4y ago
  It's just not worth it. Panels have become so cheap and productive that you don't need to have them track the sun. A motor and a swivel are already prohibitively expensive. They also introduce a lot of failure modes to a system that is otherwise low-maintenance. It's much, much, much cheaper to just plonk down a few extra square meters of panels instead.

42 points by hhs 4y ago

that's cool and all, but if they are already anchored, why not have winches that drag one side more than the other to position the arrays towards the sun, instead of propellers which I assume you would have to run continuously? or did I miss-read something?

pencilguin 4y ago
People always seem to jump to the the most complicated and expensive design alternatives. A central pivot and a loop of rope around a motor capstan on-shore to gradually rotate the whole array would be obviously simpler and cheaper. The extreme for preferring absurd complication seems especially to show up in attempts at extracting wave energy. So, wave energy startups almost always fail; not because the energy is insufficient or hard to extract, but just because they seem compelled to field doomed, overpriced, expensive, and fragile designs. I sometimes wonder if you need to have foolishly complicated tech to impress investors, who would be disinclined to fund what they feel like they could understand. Generally, if you are putting stuff out in the water, apparatus that might need servicing should be onshore, with the simplest possible connection out to stuff in the water. For wave energy collection, make your collectors suck air out of a big, shared pipe from shore, with a turbine in the inlet onshore. You don't want your expensive, fragile turbine attacked by salt water and crashing waves, and you don't want lots of little ones where one big, shared one does better. Apparatus to collect wave energy should be always under the surface, away from crashing surface waves.

swader999 4y ago

Obvious but of course I never thought off it.

lbriner 4y ago

Kind of curious but I think people can get side-tracked by the idea of "scale". The thought that if something doesn't scale in the traditional way to a few very large installations, it won't work. Consider things like battery storage for the grid etc. and you might think it is a dead horse. However, what if every house had solar panels and a relatively small number of cells with a grid-tie unit. I no longer need to store an enormous amount of energy, just enough for perhaps a few hours of demand for my house. You get to soak up most of the high-sun days into batteries, you can also feed each other a little if someone is using a fair bit more energy along existing small cables. You can then feed in a much smaller number of larger power plants who can make up any remaining peaks and troughs. Don't need to store 1TW of power into a grid-scale plant, just 20M 10KW systems distributed round the entire country. Don't need to point the panels at the sun all day then!

zdragnar 4y ago
It's really location-dependent. The upper midwest US can go weeks without direct sunshine or much wind in late December through the first week of February. Batteries fed by solar simply won't suffice- even on sunny days, there are fewer hours of sun. To reduce the number of power plants in the area, we'd need to import electricity from elsewhere, at which point you need to overprovision some geographies and run significant amounts of HVDC lines across the country. Neither of these are free or without their own impacts. Whether that would be better than fission or waiting for fusion or continuing with natural gas is debatable- steel and aluminum are not entirely coal free yet either, nor is the concrete or any of the construction work. OTOH, very sunny areas like the southwest could do quite well here.
- WaitWaitWha 4y ago
  > OTOH, very sunny areas like the southwest could do quite well here. from the article: > Locations must be chosen carefully to avoid tidal forces and stormy weather from destroying the panels as well as their mooring and anchoring systems. That sort of removes anywhere we have hurricanes, tropical cyclones, typhoons and such; mostly where we have ample sun. That said, it does look interesting. Maybe if they have some more built-in self protection from weather?
  - zdragnar 4y ago
    Anything in a climate that could freeze would require heating elements much like windmills currently do. Unfortunately, windmills don't accumulate ice very quickly, compared to a floating solar panel would in say Lake Superior in winter. I imagine that hurricanes would also rule out much of the east coast and gulf of mexico, leaving... California and Hawaii?
- kibwen 4y ago
  In this specific example, the Midwest is ideal for wind farms: https://www.eia.gov/energyexplained/wind/where-wind-power-is-harnessed.php https://www.eia.gov/energyexplained/wind/where-wind-power-is... . Wind is already the majority of the energy generated in Iowa: https://en.m.wikipedia.org/wiki/Wind_power_in_Iowa https://en.m.wikipedia.org/wiki/Wind_power_in_Iowa So as far as being location-dependent, indeed it is, though that doesn't preclude other renewable solutions.

zucked 4y ago

The article mentions that the water helps regulate the solar array temperature, ostensibly because the water is used as a heat sink. Does the thermal equation even out such that the body of water temperature is not dramatically impacted? Example: If the solar panels are absorbing sunlight before it can reach the water, the water would be colder. But, if the solar panels are using the water as a heat sink/cooler, the water temp could be brought up in temperature. And what about the blockage of the light? That will inhibit growth of algae and plants underwater. I can see how this might be super useful for man-made bodies of water (for drinking, runoff, etc) but it seems it might be a bit impactful on natural bodies of water.

ZeroGravitas 4y ago
Blockage of the light can be a positive. Some locations use floating black plastic spheres to achieve this goal.
- euroderf 4y ago
  Wouldn't floating white spheres make more sense ? If the goal is to avoid overly warm mater.
  - weberer 4y ago
    White would reflect more, but also allow light to pass through. The goal of these are to completely block light to prevent algae growth.
  - Tyrannosaur 4y ago
    https://youtu.be/uxPdPpi5W4o?t=403 https://youtu.be/uxPdPpi5W4o?t=403 Veritasium video about Los Angeles' reservoir black spheres project. They used black because - The goal was light-blocking more than anything else; black worked best - The black pigment held up to the environment (especially UV degradation) better than anything else they tried I expect the second point was the most important thing. Black plastic is very stable.
- zucked 4y ago

0cf8612b2e1e 4y ago

Conceptually, I think floating solar could be more efficient, but it strikes me as having significantly higher installation and operational expenses vs ground. If you have nowhere else to install, sure, but I’m long odds that this is cost effective vs more panels installed (more cheaply) on the shore.

pencilguin 4y ago
Alternatively, floating PV could be a lot cheaper than installing solid mounting hardware to hold panels off the ground and kept from blowing away in wind that gets under them.

deleted 4y ago

[deleted]

didgetmaster 4y ago

I have often wondered why rooftop solar does not have some kind of tilting system to aim the panel at the sun more without an expensive and sophisticated tracking system. You could mount each panel on a swivel that has a spring on one side and a screw drive on the other side. At night when no power is being generated, the spring causes the panel to automatically move so it is pointing at a slight angle (e.g. 15 degrees) to the east. When the sun comes up in the morning and the panel starts generating power, it also activates a very small motor that turns the screw every few minutes to begin a slow tilt toward the west. This continues all day until the sun goes down and the process resets.

cedilla 4y ago
It's just not worth it. Panels have become so cheap and productive that you don't need to have them track the sun. A motor and a swivel are already prohibitively expensive. They also introduce a lot of failure modes to a system that is otherwise low-maintenance. It's much, much, much cheaper to just plonk down a few extra square meters of panels instead.