47 ms·

I may be misunderstanding but it seems like most of your comment completely ignores batteries?

new_realist 7y ago
Batteries double the cost of solar for a 24 hour storage cycle. If you want to store energy for 48 hours, the cost doubles again. 96 hours? Doubles again. Want to store a mere 10% of US electrical generation from summer to use in winter? Literally 52 trillion (yes, trillion) dollars if you use batteries. A bit expensive, even if you spread the cost over 25 years. Pumped hydro, CAES and hydrogen stored in salt caverns are much cheaper at that scale.
- Retric 7y ago
  Only if you’re failing to build enough solar. There is zero reason to ramp up storage rather than reduce the need for it. Over production is cheaper than any other option and reduces the need for longer term storage as daily solar output never drops to zero. Solar is cheap enough it’s still cost competitive if you assume significant power production is wasted. Further, battery systems are designed to avoid full discharge, design for 99.5% of the time and you have spare capacity for the last 0.5%.
  - jacquesm 7y ago
    > daily solar output never drops to zero True, but it is also almost never 'rated power'. Typically a solar installation will deliver somewhere between 30 and 50% of rated power on average, depending on your latitude it might be even lower. The times when solar panels work at their best is during clear winter days and when they are capable of two axis adjustment. Because of the cost of such an installation the typical choice is to install more panels running at lower efficiency. And you'd need to size your batteries for those worst case scenarios of obscured sub in which case your panels might only output between 5 and 10% of their nominal capacity. For reference, my 1600W array is outputting 15.9 Watts right now, earlier, at the best time of the day it was making about 300W due to the sky being overcast. If I had to rely on battery power to make up the difference I would not be able to make it on solar alone. A healthy mix uses both solar and windpower, hydro if you have access to it (it is by far the most stable of the three and capable of providing baseline power without any tricks).
    - Retric 7y ago
      The economics of residential solar is heavily tied to local conditions. But, for grid solar there is little reasons to build it in the north rather than just move electricity from the south. We are already below 2c/kWh for solar power in some areas, the average consumer price is 13.27 cents per kilowatt hour in the US. That’s a lot of wiggle room. Let’s assume 50% over production that’s 4c/kWh, backed up by 60h worth of batteries and transmission and your still cheaper than Nuclear while covering base load and peaking power needs. Further at National grid scale 50% over production an 60h of batteries is crazy overkill.
      - jacquesm 7y ago
        > But, for grid solar there is little reasons to build it in the north rather than just move electricity from the south. That's true, and if you're going to ship it then HVDC lines running East/West can add a couple of hours overlap as well. All this focus on rooftop solar is nice because it is decentralized but quite a few parts of a structural solution will not come from rooftop solar but from very large grid scale installations.
      - xyzzyz 7y ago
        > We are already below 2c/kWh for solar power in some areas Yes, the power is very cheap exactly when nobody needs it. > Let’s assume 50% over production that’s 4c/kWh, backed up by 60h worth of batteries and transmission and your still cheaper than Nuclear while covering base load and peaking power needs. Can I see your calculations? Last time I did the math, building enough batteries to store 48 hours worth of US energy use was simply not viable.
        Retric 7y ago
        Note as this is crazy overkill I am ignoring battery and lithium shortages of actually trying to do this. Any such transition would aim to minimize such costs. This is also not the kind of thing you do in a weekend long term pricing is required. Batteries are predicted to cost 62$/kWh or 62 Billion$ per tWh in 2030 assuming no supply shortages. We can’t build anywhere near that many batteries by then, so it seems like a reasonable baseline long term. Further, by having vastly more batteries than required they end up with fewer and longer discharge cycles which extends lifespan. Current system are also deigned for much shorter lifespans because of rapid battery price drops. Based on that and further tech progress a 20-30 year lifespan seems reasonable I will use 25. Capacity is also going to drop over time and installation and maintenance costs are > 0 so I am going to add 10% ‘other’ and ignore 7% of US grid electricity generation being hydroelectric. US annual electricity usage is ~4,000TWh / 365.24 days per year / 24h * 60h = 1.7 trillion dollars that’s a lot of money but the US can easily borrow on that scale for cheap. Further over 25 years that’s 4,000 TWH * 25 = 96,000 TWH for 1.7 Trillion dollars or 1.70$ for 96kWh or ~1.78c/kWh * 1.1 so call it 2c/kWh. Most of this power would of course come directly from solar generation, but having that many batteries is what transforms intermittent solar into peaking power. Add 4c/kWh for crazy overkill on solar and you’re at 6c/kWh to have both base load and peaking power power. Though you still need to add significant new transmission and would have significant losses associated with charging and discharging batteries etc. Still add another 2c/kWh for all the costs I am not including and your still cheaper than Nuclear though not by as much. PS: At grid scale wind and hydro further reduce battery storage requirements. Combined with excess though more reasonable generation say 1.5x and averaging across huge geographic areas 15h of battery power is probably significant overkill.

Batteries double the cost of solar for a 24 hour storage cycle. If you want to store energy for 48 hours, the cost doubles again. 96 hours? Doubles again. Want to store a mere 10% of US electrical generation from summer to use in winter? Literally 52 trillion (yes, trillion) dollars if you use batteries. A bit expensive, even if you spread the cost over 25 years. Pumped hydro, CAES and hydrogen stored in salt caverns are much cheaper at that scale.

Retric 7y ago
Only if you’re failing to build enough solar. There is zero reason to ramp up storage rather than reduce the need for it. Over production is cheaper than any other option and reduces the need for longer term storage as daily solar output never drops to zero. Solar is cheap enough it’s still cost competitive if you assume significant power production is wasted. Further, battery systems are designed to avoid full discharge, design for 99.5% of the time and you have spare capacity for the last 0.5%.
- jacquesm 7y ago
  > daily solar output never drops to zero True, but it is also almost never 'rated power'. Typically a solar installation will deliver somewhere between 30 and 50% of rated power on average, depending on your latitude it might be even lower. The times when solar panels work at their best is during clear winter days and when they are capable of two axis adjustment. Because of the cost of such an installation the typical choice is to install more panels running at lower efficiency. And you'd need to size your batteries for those worst case scenarios of obscured sub in which case your panels might only output between 5 and 10% of their nominal capacity. For reference, my 1600W array is outputting 15.9 Watts right now, earlier, at the best time of the day it was making about 300W due to the sky being overcast. If I had to rely on battery power to make up the difference I would not be able to make it on solar alone. A healthy mix uses both solar and windpower, hydro if you have access to it (it is by far the most stable of the three and capable of providing baseline power without any tricks).
  - Retric 7y ago
    The economics of residential solar is heavily tied to local conditions. But, for grid solar there is little reasons to build it in the north rather than just move electricity from the south. We are already below 2c/kWh for solar power in some areas, the average consumer price is 13.27 cents per kilowatt hour in the US. That’s a lot of wiggle room. Let’s assume 50% over production that’s 4c/kWh, backed up by 60h worth of batteries and transmission and your still cheaper than Nuclear while covering base load and peaking power needs. Further at National grid scale 50% over production an 60h of batteries is crazy overkill.
    - jacquesm 7y ago
      > But, for grid solar there is little reasons to build it in the north rather than just move electricity from the south. That's true, and if you're going to ship it then HVDC lines running East/West can add a couple of hours overlap as well. All this focus on rooftop solar is nice because it is decentralized but quite a few parts of a structural solution will not come from rooftop solar but from very large grid scale installations.
    - xyzzyz 7y ago
      > We are already below 2c/kWh for solar power in some areas Yes, the power is very cheap exactly when nobody needs it. > Let’s assume 50% over production that’s 4c/kWh, backed up by 60h worth of batteries and transmission and your still cheaper than Nuclear while covering base load and peaking power needs. Can I see your calculations? Last time I did the math, building enough batteries to store 48 hours worth of US energy use was simply not viable.
      - Retric 7y ago
        Note as this is crazy overkill I am ignoring battery and lithium shortages of actually trying to do this. Any such transition would aim to minimize such costs. This is also not the kind of thing you do in a weekend long term pricing is required. Batteries are predicted to cost 62$/kWh or 62 Billion$ per tWh in 2030 assuming no supply shortages. We can’t build anywhere near that many batteries by then, so it seems like a reasonable baseline long term. Further, by having vastly more batteries than required they end up with fewer and longer discharge cycles which extends lifespan. Current system are also deigned for much shorter lifespans because of rapid battery price drops. Based on that and further tech progress a 20-30 year lifespan seems reasonable I will use 25. Capacity is also going to drop over time and installation and maintenance costs are > 0 so I am going to add 10% ‘other’ and ignore 7% of US grid electricity generation being hydroelectric. US annual electricity usage is ~4,000TWh / 365.24 days per year / 24h * 60h = 1.7 trillion dollars that’s a lot of money but the US can easily borrow on that scale for cheap. Further over 25 years that’s 4,000 TWH * 25 = 96,000 TWH for 1.7 Trillion dollars or 1.70$ for 96kWh or ~1.78c/kWh * 1.1 so call it 2c/kWh. Most of this power would of course come directly from solar generation, but having that many batteries is what transforms intermittent solar into peaking power. Add 4c/kWh for crazy overkill on solar and you’re at 6c/kWh to have both base load and peaking power power. Though you still need to add significant new transmission and would have significant losses associated with charging and discharging batteries etc. Still add another 2c/kWh for all the costs I am not including and your still cheaper than Nuclear though not by as much. PS: At grid scale wind and hydro further reduce battery storage requirements. Combined with excess though more reasonable generation say 1.5x and averaging across huge geographic areas 15h of battery power is probably significant overkill.