5 ms·

How is the energy free? You have to buy the panels and you have to pay to dispose them. You also have to pay for the "accessories" like batteries, converters et

How is the energy free? You have to buy the panels and you have to pay to dispose them. You also have to pay for the "accessories" like batteries, converters etc.

m12k 3y ago
It's sometimes "free" in the "as in beer" sense - in certain places, when the sun is shining and/or the wind is blowing enough, so much electricity is produced that it's too much for the grid to handle, so the price drops to zero (or even negative) because the producers are desperate for a place to offload the over-capacity to (and thus neither damage any equipment, nor have to pay the cost of shutting down and later restarting any more power plants than necessary).
- jmnicolas 3y ago
  Got it, thanks.
- konschubert 3y ago
  Price won’t go negative unless there are subsidies. EDIT: If you’re downvoting this, please explain to me why a solar or wind power plant owner won’t immediately shut off his plant once prices go negative. A PV curtailment takes 30 seconds or less.
  - jnsaff2 3y ago
    This is simply not true. Here in Europe it is explicit that subsidies are not paid during negative prices. It can take more than 12h for some thermal plants to pick up steam after they have shut down. So it sometimes makes sense to produce and pay in order to regain profits at the following non-negative hours.
    - konschubert 3y ago
      It takes about a minute or two to curtail a solar or a wind power plant - if you’re slow. Negative prices happen because plants are still subsidised during negative price periods. The 4 and 6 hour rules in Germany only apply to newer plants, and many phases of negative prices are shorter than that. France has the 1 hour rule apply to all renewable plants, but there are still subsidies available in the form of time-shiftable origination certificates. But all of this is improving and we are going to see prices go less negative in future.
      - hn_throwaway_99 3y ago
        Thank you for being a voice of sanity. The idea that once renewables are fully built out, and grid-scale storage is available and subsidies are no longer needed, that prices will be free or negative makes absolutely no sense.
        konschubert 3y ago
        Market prices for power will possibly be 0 for some slices of time in the day. After all, the marginal cost of producing power it is 0. But most of the time, prices will be positive since batteries will smooth out demand.
    - konschubert 3y ago
      > Here in Europe it is explicit that subsidies are not paid during negative prices. This may be approximately true for new plants coming online. But existing plants get to keep their old subsidy schemes for a period of N years, at least here in Germany.
    - limpanz 3y ago
      >This is simply not true. Here in Europe it is explicit that subsidies are not paid during negative prices. Well in Europe you can sell guarantee of origins. This drives down opex for a solar plant, at least the plants i manage in my job on the day-ahead market.
      - konschubert 3y ago
        It results in a nonzero strike price, yes.
  - beefield 3y ago
    Because the owner does not typically sell with a market price but with a power purchase agreement where the buyer agrees to buy all electricity produced at the agreed price. (This is an educated guess, not knowledge, so take with a grain of salt.)
    - konschubert 3y ago
      It is true that the plants have power purchase agreements, but: The owner can still buy back the power in the spot market and turn off his plant. He can then deliver the power he bought on the spot market to the PPA. If prices are negative, this means the owner gets paid for turning off the plant buying back the power. So the plant still gets curtailed. All this is assuming no subsidies and that the PPAs don’t contain any weird origination provisions.
  - Scoundreller 3y ago
    I’d think a PV panel runs cooler under load since it diverts ~25% of the light energy hitting it down the wire as electricity instead of just heating up the panel. Otherwise where else is the light energy going with no load? If that theory is correct, paying someone to take your electricity is worthwhile. Of course, it could operate its own shunt load on-site but not worth it if it runs a few hours a year. And I’ve no idea if a panel has a longer or shorter lifespan if it just runs hotter but unloaded. But definitely going to take a hit to production if prices go positive in 5 minutes but your panel is baking.
    - konschubert 3y ago
      It’s true that a panel runs cooler under load but this does not affect lifespan in a way that warrants paying even $0.001 to deliver the power.
      - Scoundreller 3y ago
        If we assume 1st order decay, 1h at at a 10C hotter temperature will reduce lifespan by 2-3h. And like I said, hot panels reduce production so in 5 or 50 minutes when rates are positive, losing 5-10% of your production is no Bueno. Panels usually have passive cooling, so if there’s little wind… It really sounds like nobody has modelled. There is some negative value worth selling for but nobody seems to know what it is (or keeps it a secret)
- jnsaff2 3y ago
  Solar inverters can curtail super easy. It’s the thermal power plants that sometimes can’t, or rather it could be beneficial for them to pay for a few hours and not let off steam until there are profitable hours again. I’m pretty sure that the arbitrage possibility is made use of by building batteries to even out the duck curve.
  - hn_throwaway_99 3y ago
    > I’m pretty sure that the arbitrage possibility is made use of by building batteries to even out the duck curve. You are absolutely correct, which is why these assumptions that building out lots of solar will result in free or even negatively priced energy make no sense. Currently these arbitrage possibilities are infrequent enough that they can't be exploited profitably. There just aren't enough super sunny days where an absolute excess of power is generated that would make it possible for, say, a battery farm to get built out to capture that storage. But everyone knows storage will be essential as renewable energy makes up more of overall power generation, and at that point it will make sense for power producers to save up their excess "sunny day" energy to sell it at other times.
    - jmopp 3y ago
      If we're at the point where power producers are saving up excess sunny-day energy to sell at other times, then we've solved renewable energy's infamous base-load problem.
      - hn_throwaway_99 3y ago
        Exactly, that's my whole point. Once renewables become a large majority of overall power production, it will be essential that we have adequate storage to account for the variability of renewables. Thus, the original idea that started this comment thread that once we get tons of renewables that energy will be free or negative (e.g. "road transport becomes nearly free") doesn't make any sense. Wholesale prices only go negative for a relatively small percentage of the time currently due to lack of storage and government subsidies.
- huytersd 3y ago
  On a tangent, is there a way to “dump” excess electricity (other than cutting off production). Like passing it into the ground or something.
  - hn_throwaway_99 3y ago
    No. There always needs to be a load to balance out the power generation on the grid. Ideally, when there is excess generation, load (that is, work) can be added in some form of battery for later useful discharge, like: charging a battery, pumping water up a hill, spinning flywheels faster, etc. In one interesting example, some large industrial users that operate big freezers will take the freezer temp much lower when there is excess generation (i.e. the freezer needs to be below 0F, but it will go way below that when energy is cheap).
  - wcoenen 3y ago
    Basically you need a big resistor with sufficient cooling. Dissipating megawatts of power is done routinely this way, during load testing of big generators. But I imagine it becomes more of an engineering problem at grid scale, where you might need to dump hundreds of megawatts to make a difference. Cooling starts to require more significant infrastructure and/or environmental impact. E.g. the gigawatts of thermal waste of a nuclear power plants either heats a local river or needs to be dumped in the atmosphere with those big hyperboloid cooling towers.
  - Kon5ole 3y ago
    You could generate hydrogen. Install a few hundred MW's worth of hydrolyzers around the continent and direct all excess there. If there is no excess, they simply don't produce. I feel that this basically has to happen sooner or later when the political obstacles to producing your own energy are removed. Electricity in several regions fluctuates between negative to 30-40 cents per kwh, having a storage mechanism like this to extract the differences as profit has to be a money-fountain, and it's not even expensive or difficult to build.
Dylan16807 3y ago
Very very high solar buildout would lead to nearly free electricity around noon on most days. The plants would actually make money in the morning and evening, and on less bright days.
- hn_throwaway_99 3y ago
  That's not how it would work, and folks are extrapolating the current situation, with very limited energy storage, to a future where storage will be essential. The reason electricity is "free" on very sunny days currently is because there is little/no storage for it, and systems aren't built to be able to capture the value of that excess energy. However, in a future where nearly all energy is from renewable sources, storage will be essential. So it's highly likely at that point that that excess energy will just be used for pumped storage, or hydrogen generation, or whatever other storage systems will exist.
  - Grimburger 3y ago
    > That's not how it would work The wholesale electricity price on the Australian NEM, which covers 9 million dwellings goes negative basically every day, there's 11 million dwellings in the entire country. You can see the price in the bottom graph here: https://opennem.org.au/energy/nem/?range=7d&interval=30m&view=discrete-time https://opennem.org.au/energy/nem/?range=7d&interval=30m&vie...
    - hn_throwaway_99 3y ago
      Talk about taking a quote out of context. The full sentence was: > That's not how it would work, and folks are extrapolating the current situation, with very limited energy storage, to a future where storage will be essential. Again, right now in Australia, grid-scale storage is extremely limited (which is excellently highlighted in your link in one of the tables under "loads", at only .9%). Power prices go negative because on the grid generation always needs to be matched with demand, and there basically isn't a place to "put" excess generation. I'm addition, while I'm not familiar with the specifics in Australia, many places have government subsidies that can make renewable generation profitable even when prices go negative. Here are 2 articles, on Texas and Germany, explaining how and why prices go negative, and it's basically always due to a lack of storage and government subsidies: https://www.rstreet.org/commentary/understanding-negative-prices-in-the-texas-electricity-market/ https://www.rstreet.org/commentary/understanding-negative-pr... https://www.cleanenergywire.org/factsheets/why-power-prices-turn-negative https://www.cleanenergywire.org/factsheets/why-power-prices-...

How is the energy free? You have to buy the panels and you have to pay to dispose them. You also have to pay for the "accessories" like batteries, converters etc.

m12k 3y ago

It's sometimes "free" in the "as in beer" sense - in certain places, when the sun is shining and/or the wind is blowing enough, so much electricity is produced that it's too much for the grid to handle, so the price drops to zero (or even negative) because the producers are desperate for a place to offload the over-capacity to (and thus neither damage any equipment, nor have to pay the cost of shutting down and later restarting any more power plants than necessary).

jmnicolas 3y ago
Got it, thanks.
konschubert 3y ago
Price won’t go negative unless there are subsidies. EDIT: If you’re downvoting this, please explain to me why a solar or wind power plant owner won’t immediately shut off his plant once prices go negative. A PV curtailment takes 30 seconds or less.
- jnsaff2 3y ago
  This is simply not true. Here in Europe it is explicit that subsidies are not paid during negative prices. It can take more than 12h for some thermal plants to pick up steam after they have shut down. So it sometimes makes sense to produce and pay in order to regain profits at the following non-negative hours.
  - konschubert 3y ago
    It takes about a minute or two to curtail a solar or a wind power plant - if you’re slow. Negative prices happen because plants are still subsidised during negative price periods. The 4 and 6 hour rules in Germany only apply to newer plants, and many phases of negative prices are shorter than that. France has the 1 hour rule apply to all renewable plants, but there are still subsidies available in the form of time-shiftable origination certificates. But all of this is improving and we are going to see prices go less negative in future.
    - hn_throwaway_99 3y ago
      Thank you for being a voice of sanity. The idea that once renewables are fully built out, and grid-scale storage is available and subsidies are no longer needed, that prices will be free or negative makes absolutely no sense.
      - konschubert 3y ago
        Market prices for power will possibly be 0 for some slices of time in the day. After all, the marginal cost of producing power it is 0. But most of the time, prices will be positive since batteries will smooth out demand.
  - konschubert 3y ago
    > Here in Europe it is explicit that subsidies are not paid during negative prices. This may be approximately true for new plants coming online. But existing plants get to keep their old subsidy schemes for a period of N years, at least here in Germany.
  - limpanz 3y ago
    >This is simply not true. Here in Europe it is explicit that subsidies are not paid during negative prices. Well in Europe you can sell guarantee of origins. This drives down opex for a solar plant, at least the plants i manage in my job on the day-ahead market.
    - konschubert 3y ago
      It results in a nonzero strike price, yes.
- beefield 3y ago
  Because the owner does not typically sell with a market price but with a power purchase agreement where the buyer agrees to buy all electricity produced at the agreed price. (This is an educated guess, not knowledge, so take with a grain of salt.)
  - konschubert 3y ago
    It is true that the plants have power purchase agreements, but: The owner can still buy back the power in the spot market and turn off his plant. He can then deliver the power he bought on the spot market to the PPA. If prices are negative, this means the owner gets paid for turning off the plant buying back the power. So the plant still gets curtailed. All this is assuming no subsidies and that the PPAs don’t contain any weird origination provisions.
- Scoundreller 3y ago
  I’d think a PV panel runs cooler under load since it diverts ~25% of the light energy hitting it down the wire as electricity instead of just heating up the panel. Otherwise where else is the light energy going with no load? If that theory is correct, paying someone to take your electricity is worthwhile. Of course, it could operate its own shunt load on-site but not worth it if it runs a few hours a year. And I’ve no idea if a panel has a longer or shorter lifespan if it just runs hotter but unloaded. But definitely going to take a hit to production if prices go positive in 5 minutes but your panel is baking.
  - konschubert 3y ago
    It’s true that a panel runs cooler under load but this does not affect lifespan in a way that warrants paying even $0.001 to deliver the power.
    - Scoundreller 3y ago
      If we assume 1st order decay, 1h at at a 10C hotter temperature will reduce lifespan by 2-3h. And like I said, hot panels reduce production so in 5 or 50 minutes when rates are positive, losing 5-10% of your production is no Bueno. Panels usually have passive cooling, so if there’s little wind… It really sounds like nobody has modelled. There is some negative value worth selling for but nobody seems to know what it is (or keeps it a secret)
jnsaff2 3y ago
Solar inverters can curtail super easy. It’s the thermal power plants that sometimes can’t, or rather it could be beneficial for them to pay for a few hours and not let off steam until there are profitable hours again. I’m pretty sure that the arbitrage possibility is made use of by building batteries to even out the duck curve.
- hn_throwaway_99 3y ago
  > I’m pretty sure that the arbitrage possibility is made use of by building batteries to even out the duck curve. You are absolutely correct, which is why these assumptions that building out lots of solar will result in free or even negatively priced energy make no sense. Currently these arbitrage possibilities are infrequent enough that they can't be exploited profitably. There just aren't enough super sunny days where an absolute excess of power is generated that would make it possible for, say, a battery farm to get built out to capture that storage. But everyone knows storage will be essential as renewable energy makes up more of overall power generation, and at that point it will make sense for power producers to save up their excess "sunny day" energy to sell it at other times.
  - jmopp 3y ago
    If we're at the point where power producers are saving up excess sunny-day energy to sell at other times, then we've solved renewable energy's infamous base-load problem.
    - hn_throwaway_99 3y ago
      Exactly, that's my whole point. Once renewables become a large majority of overall power production, it will be essential that we have adequate storage to account for the variability of renewables. Thus, the original idea that started this comment thread that once we get tons of renewables that energy will be free or negative (e.g. "road transport becomes nearly free") doesn't make any sense. Wholesale prices only go negative for a relatively small percentage of the time currently due to lack of storage and government subsidies.
huytersd 3y ago
On a tangent, is there a way to “dump” excess electricity (other than cutting off production). Like passing it into the ground or something.
- hn_throwaway_99 3y ago
  No. There always needs to be a load to balance out the power generation on the grid. Ideally, when there is excess generation, load (that is, work) can be added in some form of battery for later useful discharge, like: charging a battery, pumping water up a hill, spinning flywheels faster, etc. In one interesting example, some large industrial users that operate big freezers will take the freezer temp much lower when there is excess generation (i.e. the freezer needs to be below 0F, but it will go way below that when energy is cheap).
- wcoenen 3y ago
  Basically you need a big resistor with sufficient cooling. Dissipating megawatts of power is done routinely this way, during load testing of big generators. But I imagine it becomes more of an engineering problem at grid scale, where you might need to dump hundreds of megawatts to make a difference. Cooling starts to require more significant infrastructure and/or environmental impact. E.g. the gigawatts of thermal waste of a nuclear power plants either heats a local river or needs to be dumped in the atmosphere with those big hyperboloid cooling towers.
- Kon5ole 3y ago
  You could generate hydrogen. Install a few hundred MW's worth of hydrolyzers around the continent and direct all excess there. If there is no excess, they simply don't produce. I feel that this basically has to happen sooner or later when the political obstacles to producing your own energy are removed. Electricity in several regions fluctuates between negative to 30-40 cents per kwh, having a storage mechanism like this to extract the differences as profit has to be a money-fountain, and it's not even expensive or difficult to build.

Dylan16807 3y ago

Very very high solar buildout would lead to nearly free electricity around noon on most days. The plants would actually make money in the morning and evening, and on less bright days.

hn_throwaway_99 3y ago
That's not how it would work, and folks are extrapolating the current situation, with very limited energy storage, to a future where storage will be essential. The reason electricity is "free" on very sunny days currently is because there is little/no storage for it, and systems aren't built to be able to capture the value of that excess energy. However, in a future where nearly all energy is from renewable sources, storage will be essential. So it's highly likely at that point that that excess energy will just be used for pumped storage, or hydrogen generation, or whatever other storage systems will exist.
- Grimburger 3y ago
  > That's not how it would work The wholesale electricity price on the Australian NEM, which covers 9 million dwellings goes negative basically every day, there's 11 million dwellings in the entire country. You can see the price in the bottom graph here: https://opennem.org.au/energy/nem/?range=7d&interval=30m&view=discrete-time https://opennem.org.au/energy/nem/?range=7d&interval=30m&vie...
  - hn_throwaway_99 3y ago
    Talk about taking a quote out of context. The full sentence was: > That's not how it would work, and folks are extrapolating the current situation, with very limited energy storage, to a future where storage will be essential. Again, right now in Australia, grid-scale storage is extremely limited (which is excellently highlighted in your link in one of the tables under "loads", at only .9%). Power prices go negative because on the grid generation always needs to be matched with demand, and there basically isn't a place to "put" excess generation. I'm addition, while I'm not familiar with the specifics in Australia, many places have government subsidies that can make renewable generation profitable even when prices go negative. Here are 2 articles, on Texas and Germany, explaining how and why prices go negative, and it's basically always due to a lack of storage and government subsidies: https://www.rstreet.org/commentary/understanding-negative-prices-in-the-texas-electricity-market/ https://www.rstreet.org/commentary/understanding-negative-pr... https://www.cleanenergywire.org/factsheets/why-power-prices-turn-negative https://www.cleanenergywire.org/factsheets/why-power-prices-...