6 ms·

New device can harvest indoor light to power electronics

58 points by tdrnd 9y ago

627467 9y ago
How much efficiency improvement over calculator solar-cells are we talking about? It's not like we couldn't power basic electronics (like solar powered calculators) indoor before.
- bArray 9y ago
  Apparently solar cells larger than a calculator one can give about 30mA, 5V at peak power output [1]. We really need to know surface area and lumen to know how good this thing performs. [1] https://www.amazon.com/53X30mm-Micro-Power-Solar-Panels/dp/B01BFX65YK/ https://www.amazon.com/53X30mm-Micro-Power-Solar-Panels/dp/B...
  - wlesieutre 9y ago
    Units point of interest, the luminous flux per area is called "illuminance" and measured in lux (lumens per square meter) or footcandles (lumens per square foot)
    - roesel 9y ago
      `footcandle` is a ridiculous name for a unit.
      - ouid 9y ago
        it's not even the right dimension.
        contingencies 9y ago
        Catchy though. Same style: Toebright?[0] Fingerbling? Nosefire? This sort of fundamentally physical compound noun has a sort of medieval ring to it. [0] In homage to Madeleine
        wlesieutre 9y ago
        Originally comes from 1 fc being the illuminance on a surface 1 foot away from a 1 candela light source. A candela being roughly the intensity of light from a candle. Intensity (candelas) breaking down to lumens per steradian. They're a measure of how bright a light is in a particular direction, rather than its total light output (which is lumens). And steradians, for the unfamiliar, being a measure of "solid angle". Steradians are to 3D angles as radians are to 2D angles. A 1 steradian solid angle projects out to an area of 1 unit^2 on the surface of a unit sphere. Fun stuff!
        wlesieutre 9y ago
        Other fun fact, 1 fc = 10.7639 lux, because that's how many square feet make up a square meter. But in the lighting industry we just pretend 1 fc = 1 lux for most conversions, because eh, close enough.
- _pmf_ 9y ago
  Welcome to Silicon Valley. > It's not like we couldn't power basic electronics (like solar powered calculators) indoor before. Yes, but could we do it in a disruptive way that changes the way we work and live (and incidentally generates a multi-billion card house) and has it been presented using slightly blurry ("authentic") stock imagery of beautiful people interacting with it in an engaging manner? That's what I thought.
- Doxin 9y ago
  Interesting side note: A lot of those calculators have a fake solar panel and just run for years and years on a single battery.
syphilis2 9y ago
I've been using Logitech's solar powered keyboard (uses traditional cells) for years and I love the product. The biggest problem are: 1) doesn't charge well in low light 2) doesn't charge well from LED light At first glance, the new approach looks to address one of those problems and possibly both.
nsxwolf 9y ago
I love the idea of reclaiming some of the energy from our lighting. Perhaps one day solar cell wall paints will be a thing.
- morcheeba 9y ago
  If those solar cells are efficient, then they'll look you've painted the walls black. Not only will the quality of the light become worse (harsher shadows from less diffuse light), you'll probably install more light bulbs to compensate.
  - tempestn 9y ago
    Exactly. Now that we're putting out primarily visible light from our bulbs, there isn't a bunch of free energy floating around there. Far better to save the energy by making the bulb as efficient as possible in the first place than to try to capture it back.
    - 21 9y ago
      Technically speaking the solar panel walls would get most of their output from the daylight, assuming you have windows, considering that it's thousand times more intense than light bulbs. But yeah, I wouldn't want to live in black glass coated rooms.
      - tempestn 9y ago
        Ha, yeah, but that's kind of like putting your jacket on under your clothes.
  - lb1lf 9y ago
    The EU incidentally created a similar problem when banning most incandescent bulbs. Well, at least in some countries. Here in Norway, most buildings are heated by electricity - so replacing incandescents with LED or fluorescent bulbs effectively means that you spend less on lighting, more on heating and the sum stays the same - except the new bulbs are costlier and (mostly) provide less comfy light. Sigh. Free lunches remain elusive.
veli_joza 9y ago
Claimed 30 mW may not seem a lot, but most of electronic sensors (even displays) are only used for short period of time. You continuously collect charge over time, often in a supercapacitor, while most of device circuitry is dormant. At some time the device wakes to take measurements, transmit data over some wireless technology, schedule next wake-up and then goes back to sleep. Even if you need measurements every minute, 30 mW is plenty for these kinds of devices to do their work.
owenversteeg 9y ago
TL;DR it's a special kind of solar panel that works better in low light conditions. Super cheap solar panels are around 11% efficient, average cells are around 18%, and these are around 29% efficient. So about a 50%-ish improvement. It is a fascinating breakthrough, but unfortunately even if it was 100% efficient indoor solar cells would still be pretty useless. As a rule of thumb indoor illuminance is 200-1000 lux, vs outdoor illuminance up to 120,000 lux. A lux is slightly less than 1.5e-7 watts per centimeter. So for a 500 lux room (which I'd call pretty well lit) with one of these devices the size of a smartphone you'd be harvesting 1.5e-7w/cm2/lux500 lux7cm14cm0.29 efficiency = 0.00213 watts. As cool as this breakthrough is, it's not going to get anywhere. Current solar-powered household devices (pretty much just calculators) don't really need 50% more power, and other household devices need many orders of magnitude more power. Even if it was 100% efficient, it'd still be gathering less than a hundredth of a watt. That's not coming anywhere close to useful.

58 points by tdrnd 9y ago

How much efficiency improvement over calculator solar-cells are we talking about? It's not like we couldn't power basic electronics (like solar powered calculators) indoor before.

bArray 9y ago
Apparently solar cells larger than a calculator one can give about 30mA, 5V at peak power output [1]. We really need to know surface area and lumen to know how good this thing performs. [1] https://www.amazon.com/53X30mm-Micro-Power-Solar-Panels/dp/B01BFX65YK/ https://www.amazon.com/53X30mm-Micro-Power-Solar-Panels/dp/B...
- wlesieutre 9y ago
  Units point of interest, the luminous flux per area is called "illuminance" and measured in lux (lumens per square meter) or footcandles (lumens per square foot)
  - roesel 9y ago
    `footcandle` is a ridiculous name for a unit.
    - ouid 9y ago
      it's not even the right dimension.
      - contingencies 9y ago
        Catchy though. Same style: Toebright?[0] Fingerbling? Nosefire? This sort of fundamentally physical compound noun has a sort of medieval ring to it. [0] In homage to Madeleine
      - wlesieutre 9y ago
        Originally comes from 1 fc being the illuminance on a surface 1 foot away from a 1 candela light source. A candela being roughly the intensity of light from a candle. Intensity (candelas) breaking down to lumens per steradian. They're a measure of how bright a light is in a particular direction, rather than its total light output (which is lumens). And steradians, for the unfamiliar, being a measure of "solid angle". Steradians are to 3D angles as radians are to 2D angles. A 1 steradian solid angle projects out to an area of 1 unit^2 on the surface of a unit sphere. Fun stuff!
        wlesieutre 9y ago
        Other fun fact, 1 fc = 10.7639 lux, because that's how many square feet make up a square meter. But in the lighting industry we just pretend 1 fc = 1 lux for most conversions, because eh, close enough.
_pmf_ 9y ago
Welcome to Silicon Valley. > It's not like we couldn't power basic electronics (like solar powered calculators) indoor before. Yes, but could we do it in a disruptive way that changes the way we work and live (and incidentally generates a multi-billion card house) and has it been presented using slightly blurry ("authentic") stock imagery of beautiful people interacting with it in an engaging manner? That's what I thought.
Doxin 9y ago
Interesting side note: A lot of those calculators have a fake solar panel and just run for years and years on a single battery.

syphilis2 9y ago

I've been using Logitech's solar powered keyboard (uses traditional cells) for years and I love the product. The biggest problem are: 1) doesn't charge well in low light 2) doesn't charge well from LED light At first glance, the new approach looks to address one of those problems and possibly both.

nsxwolf 9y ago

I love the idea of reclaiming some of the energy from our lighting. Perhaps one day solar cell wall paints will be a thing.

morcheeba 9y ago
If those solar cells are efficient, then they'll look you've painted the walls black. Not only will the quality of the light become worse (harsher shadows from less diffuse light), you'll probably install more light bulbs to compensate.
- tempestn 9y ago
  Exactly. Now that we're putting out primarily visible light from our bulbs, there isn't a bunch of free energy floating around there. Far better to save the energy by making the bulb as efficient as possible in the first place than to try to capture it back.
  - 21 9y ago
    Technically speaking the solar panel walls would get most of their output from the daylight, assuming you have windows, considering that it's thousand times more intense than light bulbs. But yeah, I wouldn't want to live in black glass coated rooms.
    - tempestn 9y ago
      Ha, yeah, but that's kind of like putting your jacket on under your clothes.
- lb1lf 9y ago
  The EU incidentally created a similar problem when banning most incandescent bulbs. Well, at least in some countries. Here in Norway, most buildings are heated by electricity - so replacing incandescents with LED or fluorescent bulbs effectively means that you spend less on lighting, more on heating and the sum stays the same - except the new bulbs are costlier and (mostly) provide less comfy light. Sigh. Free lunches remain elusive.

veli_joza 9y ago

Claimed 30 mW may not seem a lot, but most of electronic sensors (even displays) are only used for short period of time. You continuously collect charge over time, often in a supercapacitor, while most of device circuitry is dormant. At some time the device wakes to take measurements, transmit data over some wireless technology, schedule next wake-up and then goes back to sleep. Even if you need measurements every minute, 30 mW is plenty for these kinds of devices to do their work.

owenversteeg 9y ago

TL;DR it's a special kind of solar panel that works better in low light conditions. Super cheap solar panels are around 11% efficient, average cells are around 18%, and these are around 29% efficient. So about a 50%-ish improvement. It is a fascinating breakthrough, but unfortunately even if it was 100% efficient indoor solar cells would still be pretty useless. As a rule of thumb indoor illuminance is 200-1000 lux, vs outdoor illuminance up to 120,000 lux. A lux is slightly less than 1.5e-7 watts per centimeter. So for a 500 lux room (which I'd call pretty well lit) with one of these devices the size of a smartphone you'd be harvesting 1.5e-7w/cm2/lux500 lux7cm14cm0.29 efficiency = 0.00213 watts. As cool as this breakthrough is, it's not going to get anywhere. Current solar-powered household devices (pretty much just calculators) don't really need 50% more power, and other household devices need many orders of magnitude more power. Even if it was 100% efficient, it'd still be gathering less than a hundredth of a watt. That's not coming anywhere close to useful.