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> A 60kwh car battery might cost $10k, and allow 2000 charge cycles. So each kwh cycled into and out of the battery costs 8 cents. If you can really treat the

> A 60kwh car battery might cost $10k, and allow 2000 charge cycles. So each kwh cycled into and out of the battery costs 8 cents. If you can really treat the whole cost of the battery as X cents per charge cycle, disregarding the lifetime of the car/battery, this won't work at grid scale. Someone else will build a storage facility that just charges and discharges batteries, and they will outcompete rational EV owners, because they will have economies of scale and battery banks designed for this use. It only makes sense if the EV owner can somehow get charge capacity "for free" - eg the car will be EOL after 1000 charges but the battery lasts 2000 - he should sell the extra 1000. Or alternatively if getting 8c now is better than getting 1 charge in several years time (plausible if interest rates, energy futures prices etc are right). However, this could be wrong. The same logic says rooftop solar can't exist without special subsidies, and a lot of people disagree with me there.

iso1210 4y ago
This does work today at grid scale, people use their home batteries (either on wheels or not) to charge/discharge to the grid in the UK all the time. If someone builds that storage facility to do it commercially then great. > rooftop solar can't exist without special subsidies Yet it does
- deleted 4y ago
  [deleted]
- sokoloff 4y ago
  There are special subsidies for rooftop solar here in the US (Solar Investment Tax Credit). Are there not subsidies for solar where you live? https://www.seia.org/initiatives/solar-investment-tax-credit-itc https://www.seia.org/initiatives/solar-investment-tax-credit... > The solar Investment Tax Credit (ITC) is one of the most important federal policy mechanisms to support the growth of solar energy in the United States. Since the ITC was enacted in 2006, the U.S. solar industry has grown by more than 200x - creating hundreds of thousands of jobs and investing billions of dollars in the U.S. economy in the process.
  - philipkglass 4y ago
    The same link says: The Section 48 commercial credit can be applied to both customer-sited commercial solar systems and large-scale utility solar farms. The rate is effectively at 30% until Treasury issues guidance on new wage and apprenticeship standards. Two months later, the rate will be at 6%, with an additional 24% (for a total of 30%) available for meeting these new labor standards. So utility-scale solar farms can get the same 30% credit as rooftop solar. They're both tax-advantaged compared to (e.g.) building a new gas plant, but the rooftop credit isn't any higher, at least not on the federal level. Self-consumption from rooftop solar may avoid other taxes, like sales tax, but in many states there is no sales tax on residential electricity to begin with.
    - sokoloff 4y ago
      The interesting question of there being a subsidy for rooftop solar is the difference in subsidy to me between my roof having solar panels or my roof not having solar panels, not between my subsidy for my roof having solar panels or someone else's for their field having solar panels on it.
  - iso1210 4y ago
    Not any more, other than no sales tax on the panels.
    - sokoloff 4y ago
      ?? It's part of the "Inflation Reduction Act of 2022" (and at a higher rate than before): https://www.solar.com/learn/inflation-reduction-act/ https://www.solar.com/learn/inflation-reduction-act/
      - iso1210 4y ago
        That's a foreign law applying to a foreign country
  - fwungy 4y ago
    Subsidies are a terrible way to run energy policy because they can change quickly with politics. Big players stay away from big commitments to subsidy based markets.
- mercutio2 4y ago
  I think you may have missed the point here. Rooftop solar is heavily subsidized almost everywhere it’s popular. Rooftop solar isn’t a good deal for utilities or their non-rooftop-solar customers. I say this as someone who lived off the grid on solar for years; encouraging rooftop solar may have kickstarted the learning curve for the solar panel industry, and as such may have been pretty good social policy. But it definitely owes its existence to subsidies. These days grid scale solar makes lots of sense, rooftop solar still doesn’t (and the subsidies are now harder to defend).
londons_explore 4y ago
Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. Whereas rooftop solar energy is untaxed when it powers your laptop. > It only makes sense if the EV owner can somehow get charge capacity "for free" The EV owner has the power electronics 'for free' - ie. they have almost infinite lifespan, and just a capital cost. Additionally, the variations of energy prices on the grid are really wide. There might be $100k/MWh for 5 minutes per year. It isn't worth a static operator paying the capital cost for the batteries (which also degrade with time) to setup for 5 minutes use per year. But it does make sense for the EV owner to do so, because his marginal cost is tiny.
- est31 4y ago
  This reminds me of how in Germany, before there has been a value added tax, there'd been a revenue tax. It was lower, but you had to pay it on every $ of revenue, even if your profit margin was very small. So a lot of businesses started to vertically integrate. Once the system switched to one where you get back the tax for the things your business buys, businesses got broken up or grew in only one of the steps of their supply chain.
- onlyrealcuzzo 4y ago
  > Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. This depends where you live and the size/efficiency of your rooftop setup, right?
- antisthenes 4y ago
  > Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. Whereas rooftop solar energy is untaxed when it powers your laptop. If you completely neglect the installation part, sure. Utility-scale solar farms have massive efficiencies of scale on purchasing panels and on labor-related overhead. It's not that clear cut, basically. I think what the EV model allows is for private car owners to essentially sell a part of their car back in increments, if for some reason their driving behavior changes and they don't need to drive as much as they used to.
scythe 4y ago
>It only makes sense if the EV owner can somehow get charge capacity "for free" - eg the car will be EOL after 1000 charges but the battery lasts 2000 - he should sell the extra 1000. Plug in the numbers. A charge cycle is probably around 200 miles (not even optimistic). That means that 1000 charge cycles is 200000 miles. That's roughly the lifetime of a car. However, I have heard anecdotes that EVs should last longer, due to a simpler transmission, so this may be a little up in the air.
neallindsay 4y ago
"X cents per charge cycle" is a bit simpler than the reality. The actual wear cost of charging/discharging a big EV battery is cheaper in the middle and more expensive at the extremes. I already have to own a car for short trips most days and an occasional long trip. And when I'm not going on a long trip I have a lot of extra battery capacity that I can rent to the grid at extremely low (additional) cost to me. A dedicated battery storage facility on the other hand has to justify the entire price of the battery.
- schiffern 4y ago
  I took their numbers only as a simplified illustrative example to teach the idea. A real deployed algorithm would estimate the "degradation cost curve" over the entire DoD, and stop charging when total (fully-considered) costs exceed revenue.
bryanlarsen 4y ago
Power has two big costs: generation and distribution. Once rooftop solar power is below the cost of distribution it doesn't matter how much it costs to generate power; rooftop solar is always going to be cheaper. That milestone has been hit in some places Australia already.
- mercutio2 4y ago
  I don’t quite buy your argument. If the system still depends on distribution, someone has to pay for it. It may be that rooftop solar users will be asked to pay more for that distribution than they think is reasonable. I’m sure not excited about my grid operator proposing a $50/month minimum for electricity, it makes my panels seem worthless. But there is logic; I was being subsidized by net metering. And in future I may have to pay a cost closer to the true cost of access to the stability of the grid.

iso1210 4y ago

This does work today at grid scale, people use their home batteries (either on wheels or not) to charge/discharge to the grid in the UK all the time. If someone builds that storage facility to do it commercially then great. > rooftop solar can't exist without special subsidies Yet it does

deleted 4y ago
[deleted]
sokoloff 4y ago
There are special subsidies for rooftop solar here in the US (Solar Investment Tax Credit). Are there not subsidies for solar where you live? https://www.seia.org/initiatives/solar-investment-tax-credit-itc https://www.seia.org/initiatives/solar-investment-tax-credit... > The solar Investment Tax Credit (ITC) is one of the most important federal policy mechanisms to support the growth of solar energy in the United States. Since the ITC was enacted in 2006, the U.S. solar industry has grown by more than 200x - creating hundreds of thousands of jobs and investing billions of dollars in the U.S. economy in the process.
- philipkglass 4y ago
  The same link says: The Section 48 commercial credit can be applied to both customer-sited commercial solar systems and large-scale utility solar farms. The rate is effectively at 30% until Treasury issues guidance on new wage and apprenticeship standards. Two months later, the rate will be at 6%, with an additional 24% (for a total of 30%) available for meeting these new labor standards. So utility-scale solar farms can get the same 30% credit as rooftop solar. They're both tax-advantaged compared to (e.g.) building a new gas plant, but the rooftop credit isn't any higher, at least not on the federal level. Self-consumption from rooftop solar may avoid other taxes, like sales tax, but in many states there is no sales tax on residential electricity to begin with.
  - sokoloff 4y ago
    The interesting question of there being a subsidy for rooftop solar is the difference in subsidy to me between my roof having solar panels or my roof not having solar panels, not between my subsidy for my roof having solar panels or someone else's for their field having solar panels on it.
- iso1210 4y ago
  Not any more, other than no sales tax on the panels.
  - sokoloff 4y ago
    ?? It's part of the "Inflation Reduction Act of 2022" (and at a higher rate than before): https://www.solar.com/learn/inflation-reduction-act/ https://www.solar.com/learn/inflation-reduction-act/
    - iso1210 4y ago
      That's a foreign law applying to a foreign country
- fwungy 4y ago
  Subsidies are a terrible way to run energy policy because they can change quickly with politics. Big players stay away from big commitments to subsidy based markets.
mercutio2 4y ago
I think you may have missed the point here. Rooftop solar is heavily subsidized almost everywhere it’s popular. Rooftop solar isn’t a good deal for utilities or their non-rooftop-solar customers. I say this as someone who lived off the grid on solar for years; encouraging rooftop solar may have kickstarted the learning curve for the solar panel industry, and as such may have been pretty good social policy. But it definitely owes its existence to subsidies. These days grid scale solar makes lots of sense, rooftop solar still doesn’t (and the subsidies are now harder to defend).

londons_explore 4y ago

Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. Whereas rooftop solar energy is untaxed when it powers your laptop. > It only makes sense if the EV owner can somehow get charge capacity "for free" The EV owner has the power electronics 'for free' - ie. they have almost infinite lifespan, and just a capital cost. Additionally, the variations of energy prices on the grid are really wide. There might be $100k/MWh for 5 minutes per year. It isn't worth a static operator paying the capital cost for the batteries (which also degrade with time) to setup for 5 minutes use per year. But it does make sense for the EV owner to do so, because his marginal cost is tiny.

est31 4y ago
This reminds me of how in Germany, before there has been a value added tax, there'd been a revenue tax. It was lower, but you had to pay it on every $ of revenue, even if your profit margin was very small. So a lot of businesses started to vertically integrate. Once the system switched to one where you get back the tax for the things your business buys, businesses got broken up or grew in only one of the steps of their supply chain.
onlyrealcuzzo 4y ago
> Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. This depends where you live and the size/efficiency of your rooftop setup, right?
antisthenes 4y ago
> Rooftop solar outcompetes solar farms because energy from a solar farm pays taxes and distribution costs before it is delivered to a user. Whereas rooftop solar energy is untaxed when it powers your laptop. If you completely neglect the installation part, sure. Utility-scale solar farms have massive efficiencies of scale on purchasing panels and on labor-related overhead. It's not that clear cut, basically. I think what the EV model allows is for private car owners to essentially sell a part of their car back in increments, if for some reason their driving behavior changes and they don't need to drive as much as they used to.

scythe 4y ago

>It only makes sense if the EV owner can somehow get charge capacity "for free" - eg the car will be EOL after 1000 charges but the battery lasts 2000 - he should sell the extra 1000. Plug in the numbers. A charge cycle is probably around 200 miles (not even optimistic). That means that 1000 charge cycles is 200000 miles. That's roughly the lifetime of a car. However, I have heard anecdotes that EVs should last longer, due to a simpler transmission, so this may be a little up in the air.

neallindsay 4y ago

"X cents per charge cycle" is a bit simpler than the reality. The actual wear cost of charging/discharging a big EV battery is cheaper in the middle and more expensive at the extremes. I already have to own a car for short trips most days and an occasional long trip. And when I'm not going on a long trip I have a lot of extra battery capacity that I can rent to the grid at extremely low (additional) cost to me. A dedicated battery storage facility on the other hand has to justify the entire price of the battery.

schiffern 4y ago
I took their numbers only as a simplified illustrative example to teach the idea. A real deployed algorithm would estimate the "degradation cost curve" over the entire DoD, and stop charging when total (fully-considered) costs exceed revenue.

bryanlarsen 4y ago

Power has two big costs: generation and distribution. Once rooftop solar power is below the cost of distribution it doesn't matter how much it costs to generate power; rooftop solar is always going to be cheaper. That milestone has been hit in some places Australia already.

mercutio2 4y ago
I don’t quite buy your argument. If the system still depends on distribution, someone has to pay for it. It may be that rooftop solar users will be asked to pay more for that distribution than they think is reasonable. I’m sure not excited about my grid operator proposing a $50/month minimum for electricity, it makes my panels seem worthless. But there is logic; I was being subsidized by net metering. And in future I may have to pay a cost closer to the true cost of access to the stability of the grid.