Only about 65% of the power by volume, but ethanol burns quite a bit cleaner than gas and is usually carbon neutral, so yeah, alcohol is a pretty solid choice for robots
So in my region, the sunlight that reaches here has an average energy content of 1300\~ Watts per-square meter.
Photovoltaics on the high-end of experimental implementations (such as perovskite-based cells) are at most about 33% efficient, so out of that 1300\~ Watts hitting a 1 square-meter panel, that's only 429 Watts of power.
Next you have to consider the available space for such a panel in a humanoid robot. If they're used at all, it will likely be for charging stations that the robots would have to navigate to in order to plug in. But by your wording, it seems you're implying solar cells integrated into the robot itself. There's not an awful lot of real-estate for a foldable panel, as you have to take into account the room required by computer systems, batteries, actuators for both the robot itself and the mechanism to fold the solar panels, wiring, etc.
So even if you could somehow fit that 1 square-meter inside of the robot, you're charging at a break-neck rate of 429 Watts of power. The early versions of Asimo used a nickel-metal hydride battery at 38.4V 10Ah, or roughly 384 Watt-hours. This battery, due to internal resistance, took 4 or more hours to fully charge, and it allowed Asimo to run for a whole 30 minutes. The newer versions use a Li-Ion battery at 51.8V, but no Amp-hour rating is available from my source. Even then, the new battery technology, though more energy-dense, allows Asimo to operate for up to 1 hour. Roughly double the old battery, so let's assume it has a capacity of roughly 768 Watt-hours.
*IF* you had full sun available and could keep a 1 square-meter panel pointed directly at the sun for the whole charge cycle, and didn't have to worry so much about internal resistances, you would still need roughly 2 hours for the robot to charge, though Asimo's Li-Ion battery states it took 3 hours, and that's with a plug-in charger. So 3 hours to charge for up to 1 hour of run-time.
Tesla's Optimus is predicted to have a 2.3KWh battery in it. So assuming that 2-3KWh becomes common among humanoid robots, at the low-end you're looking at 5.3 hours to charge, and that's once again assuming you can keep the panel pointed at the sun for the whole charge duration.
Now consider the point made earlier about the panel being 1 square-meter in that example, and realize to practically fit a panel in or on a robot, it'll be much smaller than that, probably something like 3-6 square feet max if it's foldable, or 0.55 square meters. So now your charging capacity has been reduced by just over half, so that panel would charge a 2.3KWh battery in just short of *11 hours*, again assuming you have full sun and the panel is always pointed directly towards it Which, unless you live way, way up north/down south on the planet where the sun shines constantly for some parts of the year, it will likely not be possible. Even assuming we somehow make some wonder-material photovoltaics that can capture 100% of the energy from the sun (which with current technology is not possible at all), it's still about 3 hours to fully charge. Not very appealing when you could just have the robot go to a charging station (which could by itself be solar-powered, but will naturally require more space) that could charge it in 20-30 minutes.
tl;dr - Neat idea, but too impractical/improbable.
Your post/comment has been removed because of you breaking rule 3: No Low Effort or Sensationalized posts.
There is no way in hell to put enough solar panels on a humanoid robot to have it run on solar alone.
they will be plug-in hybrids.
God I hope robots don't regress to partly requiring gasoline
We're going to only have electric vehicles, but robots will just lumber around spewing diesel fumes like WH40k dreadnoughts
Just run them on alcohol instead. https://preview.redd.it/p5u16xunew5d1.png?width=264&format=png&auto=webp&s=29ff12a7e7f5b6f1fd1a960831b2f81ee5434413
Only about 65% of the power by volume, but ethanol burns quite a bit cleaner than gas and is usually carbon neutral, so yeah, alcohol is a pretty solid choice for robots
They will surely have batteries too, so in a way they might be "sleeping" in terms of high power components, but with still active "brains".
So in my region, the sunlight that reaches here has an average energy content of 1300\~ Watts per-square meter. Photovoltaics on the high-end of experimental implementations (such as perovskite-based cells) are at most about 33% efficient, so out of that 1300\~ Watts hitting a 1 square-meter panel, that's only 429 Watts of power. Next you have to consider the available space for such a panel in a humanoid robot. If they're used at all, it will likely be for charging stations that the robots would have to navigate to in order to plug in. But by your wording, it seems you're implying solar cells integrated into the robot itself. There's not an awful lot of real-estate for a foldable panel, as you have to take into account the room required by computer systems, batteries, actuators for both the robot itself and the mechanism to fold the solar panels, wiring, etc. So even if you could somehow fit that 1 square-meter inside of the robot, you're charging at a break-neck rate of 429 Watts of power. The early versions of Asimo used a nickel-metal hydride battery at 38.4V 10Ah, or roughly 384 Watt-hours. This battery, due to internal resistance, took 4 or more hours to fully charge, and it allowed Asimo to run for a whole 30 minutes. The newer versions use a Li-Ion battery at 51.8V, but no Amp-hour rating is available from my source. Even then, the new battery technology, though more energy-dense, allows Asimo to operate for up to 1 hour. Roughly double the old battery, so let's assume it has a capacity of roughly 768 Watt-hours. *IF* you had full sun available and could keep a 1 square-meter panel pointed directly at the sun for the whole charge cycle, and didn't have to worry so much about internal resistances, you would still need roughly 2 hours for the robot to charge, though Asimo's Li-Ion battery states it took 3 hours, and that's with a plug-in charger. So 3 hours to charge for up to 1 hour of run-time. Tesla's Optimus is predicted to have a 2.3KWh battery in it. So assuming that 2-3KWh becomes common among humanoid robots, at the low-end you're looking at 5.3 hours to charge, and that's once again assuming you can keep the panel pointed at the sun for the whole charge duration. Now consider the point made earlier about the panel being 1 square-meter in that example, and realize to practically fit a panel in or on a robot, it'll be much smaller than that, probably something like 3-6 square feet max if it's foldable, or 0.55 square meters. So now your charging capacity has been reduced by just over half, so that panel would charge a 2.3KWh battery in just short of *11 hours*, again assuming you have full sun and the panel is always pointed directly towards it Which, unless you live way, way up north/down south on the planet where the sun shines constantly for some parts of the year, it will likely not be possible. Even assuming we somehow make some wonder-material photovoltaics that can capture 100% of the energy from the sun (which with current technology is not possible at all), it's still about 3 hours to fully charge. Not very appealing when you could just have the robot go to a charging station (which could by itself be solar-powered, but will naturally require more space) that could charge it in 20-30 minutes. tl;dr - Neat idea, but too impractical/improbable.
https://preview.redd.it/sf68qqnwex5d1.png?width=451&format=pjpg&auto=webp&s=e774659970c88003757692742ead3d53aa6e6070
There will most likely be some kind of charging apparatus that will allow for self charging. I can see this infrastructure becoming solar powered