3 ms·

Sure, but those battery backed solar plants usually only have 2-4 hours worth of storage. They're not actually producing full output throughout the night. The

Sure, but those battery backed solar plants usually only have 2-4 hours worth of storage. They're not actually producing full output throughout the night. The cost of batteries would skyrocket if countries actually tried to provision 12 hours of battery storage. Because the US alone uses 500 GWh of electricity each hour. This is greater than the global battery production figures in 2022 [1]. 1. https://www.spglobal.com/mobility/en/research-analysis/growth-of-liion-battery-manufacturing-capacity.html https://www.spglobal.com/mobility/en/research-analysis/growt...

Retric 3y ago
You’re calculating that storage number as if the solar power plant would have produced power for 24 hours. To simplify if you have 8 hours of power and you store 1/2 of it you need 4h of storage. So our hypothetical 4GW solar power plant produces 2GW for 8 hours and 1 GW for 16. That already batter fits the demand curve than steady state output. However things get better if you instead consider real world demand and the actual production of solar panels being spread across the entire day a 4 hour of storage is close to perfect. Except, the real world isn’t a hypothetical 100% solar grid so 2h ends up working fine in most areas.
- Manuel_D 3y ago
  Again, the demand curve is the opposite of what you claim: peak production happens during the night, at around 9 pm, not during the day. You'd need to supply more energy during periods of non-production, not less. You can't get away with 50% output at night, unless you have some other energy source picking up the slack. And remember, during the winter you're getting less than 12 hours of sunlight, maybe even less than that if you consider that cloud cover eliminates 75-90% of solar power output. These factors do depend on geography. Hotter climates do see more energy use during the day to power A/C. But on the flip side, colder climates see even more energy demand during the night to heat homes. And unfortunately this also coincides when solar is producing the least amount of energy due to fewer sunlight hours, axial tilt, and more cloud cover. There are niches solar can carve out: Las Vegas and Australia have loads of empty space, clear weather, and hydroelectricity that can fill in periods of non-production. But nuclear power is a much more flexible solution. All you really need is water to cool the reactor, and 80% of the population lives within a hundred miles of the coastline (you just need water, not fresh water).
  - nicoburns 3y ago
    Energy use for heating can be quite easily reduced just by insulating houses (and installing more efficient heating equipment such as heat pumps). Do we have any idea what the cause of that 9pm spike is? That seems like a bizarre time to be the peak to me (I can't work out what the primary energy users would be at that time).
    - Manuel_D 3y ago
      Replacing gas heating with heat pumps is going to increase, not reduce, electricity use.
      - Retric 3y ago
        Replacing gas heating with solar thermal is even cheaper and doesn’t. Electric heat pumps are viable when electricity is cheap or demand is low and you want AC, the more they drive up electric costs the more alternatives become viable. Net effect you tend to see them in areas where there’s a surplus of winter electricity which also tends to be places with minimal demand for heating like Virginia rather than Mane. 46% in South Carolina, 42% in North Carolina, 30% in Virginia etc: https://www.statista.com/statistics/1327164/share-of-households-unsing-central-heat-pumps-by-state-us/ https://www.statista.com/statistics/1327164/share-of-househo...
        Manuel_D 3y ago
        Solar thermal heating is not going to produce much energy in the winter when there's fewer hours of sunlight and more hours of cloud coverage - which just so happens to coincide with places that would need heating during the winter. Solar thermal performance is worse with diffuse light (read: overcast days) than PV solar, in fact that's a big part of why it was largely abandoned in the 2000s.
        Retric 3y ago
        The main advantage of solar thermal is it’s really cheap so you can just scale collection to cover winter heating. That’s why adoption is so high in China even relatively far north. As to the US, the cost savings just isn’t that appealing for most people. It’s frankly ugly, complicated, and has minimal payoff at current prices.* Passive solar design can have significant benefits while looking much nicer. But if you’re increasing the cost of electricity or gas then suddenly it’s looking significantly more attractive. * Except of course when people want to heat a pool, that takes crazy amounts of energy. “Israel became the world leader in the use of solar energy per capita with 85% of households using solar thermal systems (3% of the primary national energy consumption)” https://en.wikipedia.org/wiki/Solar_water_heating https://en.wikipedia.org/wiki/Solar_water_heating
- XorNot 3y ago
  This is the Australia energy market price and demand dashboard[1]. Note the two peaks: 1 happens at 7am. There's very little solar at 7am even though the sun is up, but demand is at a maximum. The other happens at around 6pm - when people get home. There's also very little solar at 6pm (sun sets at 5pm in Winter, during the day it's longer). Also note the demand fall off in the evening: that's a very lopsided peak, because people stay at home (whereas in the morning they turn on the kettle, then leave). But also note the absolute magnitudes: at the minimum, which is about 4am, demand last night bottomed at about 6,800MW. The peak was 9,800MW. So even the "low demand" was 2/3rds of peak demand, and it took 8 hours to get there. Most of the night, consumption was a lot higher. But it gets worse: before you're going to recover any real capacity from your solar, the largest demand of the day is about to happen in 3 hours, with the sun just barely over the horizon. [1] https://aemo.com.au/en/energy-systems/electricity/national-electricity-market-nem/data-nem/data-dashboard-nem https://aemo.com.au/en/energy-systems/electricity/national-e...
  - Retric 3y ago
    The better you model this the better the number look. First demand falls off a cliff from midnight to 5 am, a steady state nighttime rate will be extremely wasteful but batteries can shift demand to these peaks just fine. Remember 100% of their output is offsetting battery demand which is significant even just at 9AM or 6PM. Also, your not actually getting 100% solar output over the day. Batteries that could store 50% of your hypothetical maximum are well over half of your expected average output especially in winter when these peaks are most pronounced.

Retric 3y ago

You’re calculating that storage number as if the solar power plant would have produced power for 24 hours. To simplify if you have 8 hours of power and you store 1/2 of it you need 4h of storage. So our hypothetical 4GW solar power plant produces 2GW for 8 hours and 1 GW for 16. That already batter fits the demand curve than steady state output. However things get better if you instead consider real world demand and the actual production of solar panels being spread across the entire day a 4 hour of storage is close to perfect. Except, the real world isn’t a hypothetical 100% solar grid so 2h ends up working fine in most areas.

Manuel_D 3y ago
Again, the demand curve is the opposite of what you claim: peak production happens during the night, at around 9 pm, not during the day. You'd need to supply more energy during periods of non-production, not less. You can't get away with 50% output at night, unless you have some other energy source picking up the slack. And remember, during the winter you're getting less than 12 hours of sunlight, maybe even less than that if you consider that cloud cover eliminates 75-90% of solar power output. These factors do depend on geography. Hotter climates do see more energy use during the day to power A/C. But on the flip side, colder climates see even more energy demand during the night to heat homes. And unfortunately this also coincides when solar is producing the least amount of energy due to fewer sunlight hours, axial tilt, and more cloud cover. There are niches solar can carve out: Las Vegas and Australia have loads of empty space, clear weather, and hydroelectricity that can fill in periods of non-production. But nuclear power is a much more flexible solution. All you really need is water to cool the reactor, and 80% of the population lives within a hundred miles of the coastline (you just need water, not fresh water).
- nicoburns 3y ago
  Energy use for heating can be quite easily reduced just by insulating houses (and installing more efficient heating equipment such as heat pumps). Do we have any idea what the cause of that 9pm spike is? That seems like a bizarre time to be the peak to me (I can't work out what the primary energy users would be at that time).
  - Manuel_D 3y ago
    Replacing gas heating with heat pumps is going to increase, not reduce, electricity use.
    - Retric 3y ago
      Replacing gas heating with solar thermal is even cheaper and doesn’t. Electric heat pumps are viable when electricity is cheap or demand is low and you want AC, the more they drive up electric costs the more alternatives become viable. Net effect you tend to see them in areas where there’s a surplus of winter electricity which also tends to be places with minimal demand for heating like Virginia rather than Mane. 46% in South Carolina, 42% in North Carolina, 30% in Virginia etc: https://www.statista.com/statistics/1327164/share-of-households-unsing-central-heat-pumps-by-state-us/ https://www.statista.com/statistics/1327164/share-of-househo...
      - Manuel_D 3y ago
        Solar thermal heating is not going to produce much energy in the winter when there's fewer hours of sunlight and more hours of cloud coverage - which just so happens to coincide with places that would need heating during the winter. Solar thermal performance is worse with diffuse light (read: overcast days) than PV solar, in fact that's a big part of why it was largely abandoned in the 2000s.
        Retric 3y ago
        The main advantage of solar thermal is it’s really cheap so you can just scale collection to cover winter heating. That’s why adoption is so high in China even relatively far north. As to the US, the cost savings just isn’t that appealing for most people. It’s frankly ugly, complicated, and has minimal payoff at current prices.* Passive solar design can have significant benefits while looking much nicer. But if you’re increasing the cost of electricity or gas then suddenly it’s looking significantly more attractive. * Except of course when people want to heat a pool, that takes crazy amounts of energy. “Israel became the world leader in the use of solar energy per capita with 85% of households using solar thermal systems (3% of the primary national energy consumption)” https://en.wikipedia.org/wiki/Solar_water_heating https://en.wikipedia.org/wiki/Solar_water_heating
XorNot 3y ago
This is the Australia energy market price and demand dashboard[1]. Note the two peaks: 1 happens at 7am. There's very little solar at 7am even though the sun is up, but demand is at a maximum. The other happens at around 6pm - when people get home. There's also very little solar at 6pm (sun sets at 5pm in Winter, during the day it's longer). Also note the demand fall off in the evening: that's a very lopsided peak, because people stay at home (whereas in the morning they turn on the kettle, then leave). But also note the absolute magnitudes: at the minimum, which is about 4am, demand last night bottomed at about 6,800MW. The peak was 9,800MW. So even the "low demand" was 2/3rds of peak demand, and it took 8 hours to get there. Most of the night, consumption was a lot higher. But it gets worse: before you're going to recover any real capacity from your solar, the largest demand of the day is about to happen in 3 hours, with the sun just barely over the horizon. [1] https://aemo.com.au/en/energy-systems/electricity/national-electricity-market-nem/data-nem/data-dashboard-nem https://aemo.com.au/en/energy-systems/electricity/national-e...
- Retric 3y ago
  The better you model this the better the number look. First demand falls off a cliff from midnight to 5 am, a steady state nighttime rate will be extremely wasteful but batteries can shift demand to these peaks just fine. Remember 100% of their output is offsetting battery demand which is significant even just at 9AM or 6PM. Also, your not actually getting 100% solar output over the day. Batteries that could store 50% of your hypothetical maximum are well over half of your expected average output especially in winter when these peaks are most pronounced.