[HN Gopher] Floating solar panels that track the Sun
___________________________________________________________________
Floating solar panels that track the Sun
Author : hhs
Score : 33 points
Date : 2022-11-18 16:13 UTC (6 hours ago)
(HTM) web link (www.bbc.com)
(TXT) w3m dump (www.bbc.com)
| 0cf8612b2e1e wrote:
| 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 wrote:
| 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.
| zucked wrote:
| 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 wrote:
| Blockage of the light can be a positive. Some locations use
| floating black plastic spheres to achieve this goal.
| dredmorbius wrote:
| Veritasium's Derek Muller did an episode on this three years
| ago:
|
| <https://yewtu.be/watch?v=uxPdPpi5W4o>
| zucked wrote:
| Indeed - and it can help reduce evaporation, too. It's just
| that in some instances, some algae growth and some
| evaporation might be desirable.
| pencilguin wrote:
| No solar installation will block all of the light. Gaps
| between panels or rows may provide as much light as could
| be desired.
|
| Note, most aquatic wildlife benefits from shade, even where
| they depend on an algae-rooted food chain.
| euroderf wrote:
| Wouldn't floating white spheres make more sense ? If the goal
| is to avoid overly warm mater.
| weberer wrote:
| 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 wrote:
| 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.
| drtgh wrote:
| When I read the article I was only able to think in the damage
| to the underwater ecosystem by sun blocking, plus micro-
| plastics ( trophic chain, endocrine system) and chemicals from
| plastics degradation.
| didgetmaster wrote:
| 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 wrote:
| 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.
| [deleted]
| nico_h wrote:
| 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 wrote:
| 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 wrote:
| Obvious but of course I never thought off it.
| lbriner wrote:
| 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!
| kkfx wrote:
| There are few issues about _floating_ p.v.: sometimes the water
| is calm and flat so p.v. works. Sometimes not. Did you imaging
| what happen not just in mere structural terms but ALSO in
| string output?
|
| BTW I have p.v. at home, a NEW home so well insulated and all-
| electrical equipped, while I'm in the French southern Alps (at
| 1030m) so in a VERY GOOD place for p.v. y-o-y I hardly reach
| 50% self consumption. Now with an EV I need at minimum 18kWp
| p.v. to just charge A BIT my EV from Sun while WFH... That's
| because in winter, just today, I have had plenty of Sun from
| 9:30 to 13:30 so in just 4 hours I need to recharge a car
| (let's say it's not that empty, let's say 40kWh), heat water
| for house heating and sanitary hot water, plus all other home
| appliances I can concentrate in 4 hours in the morning. Imaging
| what can do those who not WFH and who live in less p.v.
| friendly areas...
|
| EVs are the formally untold way to have a THEORETICALLY stable
| smart grid (who do not exists in the real world so far) witch
| significant renewable productions with their pick loads. The
| EVs are mostly connected in big numbers across a country all
| the time and they tend to be in large number not fully charged
| not fully discharged so they can theoretically quickly start
| charging full-power and the slow down or quickly discharge to
| the grid full-power and then slow down allowing classic large
| power plants we need anyway to have time to regulate their
| production keeping the grid operation at the right frequency. A
| way to offload enormous short-life storage costs to the people
| instead to the large utilities.
|
| But no, as a small domestic p.v. "user" and an engineer I see
| NO WAY for a society to run on p.v. on scale with the actual
| tech. We can do MUCH more, like creating en masse new homes to
| lower enormously heating and cooling energy needs, we can
| subsidize EVs on scale and spread bi-directional service in
| pure DC to use them like any stationary p.v. lithium storage
| (they are already 400V DC anyway on both sides for 99% of the
| available gears on sale) to allow a stable grid while pushing
| p.v. up but without something else we have no option to keep a
| modern society operational on scale.
| pencilguin wrote:
| It should be obvious that it would be foolish to expect to
| meet all your power needs, including EV charging, with a
| small rooftop installation. Rooftop solar is to cut down on
| your power bill.
|
| "For a society to run on PV on scale" you of course rely on
| municipal, commercial, and regional "actual tech" solar and
| wind installations, storage, transmission lines and backup
| peaker plants to make up the difference. Some storage _might_
| involve lithium batteries, or other chemistries, or non-
| chemical methods such as pumped hydro or other gravitational
| methods, compressed or liquified air, or synthetic fuels such
| as hydrogen and ammonia; and commonly a mix of the above.
|
| Floating PV is sited at places where the water is habitually
| calm; calm water is always flat. Reservoirs and canals are
| favored sites, as noted in the article. Nobody talks about
| floating PV on breaking shore waves. It is hard to guess what
| could be meant by "string output", if anything, unique to
| floating PV. Solar panel output is the same, terrestrial or
| floating, and is handled the same way.
|
| We are fortunate that planning for regional renewable power
| does not depend on people who cannot see how they would
| deploy it. Others, including other engineers, can and do.
|
| Floating solar will be sited throughout most of the world.
| Ice on a solar panel does not reduce its output much, but
| being embedded in ice that, finally, breaks up could be
| damaging. Engineers are good at designing for local
| conditions.
|
| The article makes a big deal of imaginary shortfalls of
| available land for solar, but there is in fact very far from
| any such shortage. So, solar will always be sited wherever it
| is cheapest. Some places, it will be floated. Other places,
| it will share pasturage or crop land. Others, commercial
| warehouses. In France it will be, by statute, on all big
| parking lots.
| PaulDavisThe1st wrote:
| Consider a climate with a heating season. Imagine the use of
| air-source heat pumps (USA "minisplits"). Heating season
| arrives. Electrical use multiplies, perhaps 10x compared to
| non-heating season.
|
| Where does the power come from? Home installations generally
| won't cover it. Centralized installations may (hopefully will),
| but the power is needed even more overnight than during the
| day.
|
| I still think you're going to need pretty substantial central
| storage facilities.
| pencilguin wrote:
| So you build out storage facilities. Whatever turns out
| cheapest for a given site wins. Different sites will favor
| different winners. We don't know yet which few of myriad
| choices that all work will turn out cheapest, but probably
| not batteries beyond a few hours' time-shifting.
|
| There is little value in central storage, except in methods
| where economy of scale rules. Storage can otherwise be
| distributed as widely as convenience suggests, and the power
| moved around on wiring.
|
| Of course you don't build out storage until you have enough
| spare renewable generating capacity to charge it from. In the
| meantime you fill shortfalls from peaker plants, the usual
| way. As synthetic fuels like hydrogen and ammonia become
| cheaper than NG, peakers will be fired with them, either
| synthesized locally or imported, when cheaper storage runs
| low.
| zdragnar wrote:
| 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.
| kibwen wrote:
| In this specific example, the Midwest is ideal for wind
| farms: 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
|
| So as far as being location-dependent, indeed it is, though
| that doesn't preclude other renewable solutions.
| WaitWaitWha wrote:
| > 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 wrote:
| 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?
___________________________________________________________________
(page generated 2022-11-18 23:01 UTC)