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How long does the typical battery last before it needs significant new investment (major maintenance or replacement)? In other words, how long before we need to

How long does the typical battery last before it needs significant new investment (major maintenance or replacement)? In other words, how long before we need to install another 30 GW not to increase capacity, but to maintain it? I'm not a pessimist but I know that at this stage in an adoption cycle, it's all gain, but that's not the long-term reality. I'm wondering what the long-term looks like. In part, if the capacity keeps doubling, replacing 30 GW will be trivial compared to the new capacity. But eventually that will flatten out.

rpmisms 3y ago
I don't know the actual numbers on that, but I do know that stationary storage lasts much longer than e.g. EV batteries, since there are no weight restrictions, so they're cycled more gently, temps are better, they can be kept in a more optimal window, you can use things like LFP that are heavier, and BMS has more latitude with more cells to work with.
The_Colonel 3y ago
Tesla Megapacks come with a 15-year "no defect" and "energy retention" warranty. A 10 or 20 year "performance guarantee" is available for an additional cost. (an example of Li-Ion based storage, I assume it won't differ wildly with other producers) I think they can in principle last longer if used well. You can control the temperature, you can use weather forecast (as part of some network-wide forecast of future required capacity) to decide how much you should charge the batteries. You'd use the "unhealthy" charging/discharging only in extreme situations, while in the day-to-day cycles you'd keep the batteries within the healthy voltage range.
- adrianN 3y ago
  We will probably also switch to different chemistries for grid batteries. Sodium batteries for example are cheaper. Iron oxide is also interesting.
- gwd 3y ago
  Two years ago when I was considering installing a battery along with my solar panels, here was the estimations I did: 1. Additional cost of installing a 13.5kWh Tesla Powerwall was quoted as being around £12,000 2. Warranty was 80% capacity after 10 years Now, my experience with batteries in general is that once they start to go, they deteriorate pretty rapidly; so 80% after 10 years to me basically account 10 years as the lifetime of the battery. £12k for 10 years is £1.2k per year, or £100 per month: that is, the battery would have to allow me to save £100/month in electricity just to break even -- and that's before factoring in the cost of capital (i.e., if I take that £12k and invested it somewhere else, I'd have a lot more than £12k after 10 years). Even if the batteries managed to eke out a reasonable capacity for 20 years -- which seems pretty unlikely to me -- I'd still have to somehow save £50/month to break even. All in all the battery just didn't make financial sense for me as an individual. One expects that the companies doing this on an industrial scale have done the math and managed to find some economies of scale that make it profitable; but it's not out of the realm of possibility that due to a combination of optimism, overselling on the part of battery companies, and FOMO, that they've drastically overestimated the performance of their batteries, and are going to find 15 years down the road that they're beginning to fail without having paid back the capital investment used to buy them.
  - pbmonster 3y ago
    Is there a reason you did the math with a 13.5kWh battery? Do you heat a large house electrically? Do you need to charge an EV at night off that battery? Most people can get away with a significantly smaller battery - if your goal is to just get a normal house through a single night. That goal can be achieved pretty economically, especially if you're willing to use grid electricity on mornings with little sun on your panels or nights with unusually high demand.
    - gwd 3y ago
      Basically the quote we got from the local company gave us the option of a 10kWh non-Tesla battery for about £10k and a 13.5kWh Tesla battery for £12k. The math doesn't change that much between the two. I had also looked into battery sizing previously based on our annual usage; but that was over 3 years ago so I don't remember what I came up with.
- wolverine876 3y ago
  Warranty or not, I don't think I'm relying on Tesla's performance claims as data. I know, it's warrantied - 'but wasn't it your fault? What humidity level did you store it in? The moisture sensor says ...'
jillesvangurp 3y ago
If it keeps on doubling like this, a fraction of the installed base may be affected by this some 10-15 years down the line. That's kind of how the math works out. Most batteries around that time will be new ones. And that seems to be the time line that these things are sold for. They might have quite a bit of life in them beyond that of course. It's not like they just stop working. In any case, we're talking about first and second generation products here adapted from batteries designed for the automotive industry. It works and it's great but there are better options coming to market that are more optimal for grid storage. Ten years from now, this market is going to be very different in terms of cost, performance, longevity, and volumes produced and deployed. The world's electricity production per year is around 25 pwh (25000 twh) per year. So, you can do some back of the envelope math on that. We're going from hundreds of gwh to twh of battery produced per year in the next years (overall, not just grid). Each of those batteries is good for thousands of charging cycles. So if you were to charge and cycle each battery every day to add up to 1/365th of 25pw, you end up with a number of around 70twh of battery that is needed. We don't actually need that much of course since there are other options on the grid. But it just shows you that it could be doable and might be what we have in the field in a few decades. A few twh of battery on standby goes a long way and might just sit there fully charged most of the time.
ZeroGravitas 3y ago
The doubling of production is also what drives the learning curve cost decreases at a rate of 20% per doubling. Which is what has reduced battery costs by 90% over the last two decades and is widely predicted to continue. https://ourworldindata.org/learning-curve https://ourworldindata.org/learning-curve

rpmisms 3y ago

I don't know the actual numbers on that, but I do know that stationary storage lasts much longer than e.g. EV batteries, since there are no weight restrictions, so they're cycled more gently, temps are better, they can be kept in a more optimal window, you can use things like LFP that are heavier, and BMS has more latitude with more cells to work with.

The_Colonel 3y ago

Tesla Megapacks come with a 15-year "no defect" and "energy retention" warranty. A 10 or 20 year "performance guarantee" is available for an additional cost. (an example of Li-Ion based storage, I assume it won't differ wildly with other producers) I think they can in principle last longer if used well. You can control the temperature, you can use weather forecast (as part of some network-wide forecast of future required capacity) to decide how much you should charge the batteries. You'd use the "unhealthy" charging/discharging only in extreme situations, while in the day-to-day cycles you'd keep the batteries within the healthy voltage range.

adrianN 3y ago
We will probably also switch to different chemistries for grid batteries. Sodium batteries for example are cheaper. Iron oxide is also interesting.
gwd 3y ago
Two years ago when I was considering installing a battery along with my solar panels, here was the estimations I did: 1. Additional cost of installing a 13.5kWh Tesla Powerwall was quoted as being around £12,000 2. Warranty was 80% capacity after 10 years Now, my experience with batteries in general is that once they start to go, they deteriorate pretty rapidly; so 80% after 10 years to me basically account 10 years as the lifetime of the battery. £12k for 10 years is £1.2k per year, or £100 per month: that is, the battery would have to allow me to save £100/month in electricity just to break even -- and that's before factoring in the cost of capital (i.e., if I take that £12k and invested it somewhere else, I'd have a lot more than £12k after 10 years). Even if the batteries managed to eke out a reasonable capacity for 20 years -- which seems pretty unlikely to me -- I'd still have to somehow save £50/month to break even. All in all the battery just didn't make financial sense for me as an individual. One expects that the companies doing this on an industrial scale have done the math and managed to find some economies of scale that make it profitable; but it's not out of the realm of possibility that due to a combination of optimism, overselling on the part of battery companies, and FOMO, that they've drastically overestimated the performance of their batteries, and are going to find 15 years down the road that they're beginning to fail without having paid back the capital investment used to buy them.
- pbmonster 3y ago
  Is there a reason you did the math with a 13.5kWh battery? Do you heat a large house electrically? Do you need to charge an EV at night off that battery? Most people can get away with a significantly smaller battery - if your goal is to just get a normal house through a single night. That goal can be achieved pretty economically, especially if you're willing to use grid electricity on mornings with little sun on your panels or nights with unusually high demand.
  - gwd 3y ago
    Basically the quote we got from the local company gave us the option of a 10kWh non-Tesla battery for about £10k and a 13.5kWh Tesla battery for £12k. The math doesn't change that much between the two. I had also looked into battery sizing previously based on our annual usage; but that was over 3 years ago so I don't remember what I came up with.
wolverine876 3y ago
Warranty or not, I don't think I'm relying on Tesla's performance claims as data. I know, it's warrantied - 'but wasn't it your fault? What humidity level did you store it in? The moisture sensor says ...'

jillesvangurp 3y ago

If it keeps on doubling like this, a fraction of the installed base may be affected by this some 10-15 years down the line. That's kind of how the math works out. Most batteries around that time will be new ones. And that seems to be the time line that these things are sold for. They might have quite a bit of life in them beyond that of course. It's not like they just stop working. In any case, we're talking about first and second generation products here adapted from batteries designed for the automotive industry. It works and it's great but there are better options coming to market that are more optimal for grid storage. Ten years from now, this market is going to be very different in terms of cost, performance, longevity, and volumes produced and deployed. The world's electricity production per year is around 25 pwh (25000 twh) per year. So, you can do some back of the envelope math on that. We're going from hundreds of gwh to twh of battery produced per year in the next years (overall, not just grid). Each of those batteries is good for thousands of charging cycles. So if you were to charge and cycle each battery every day to add up to 1/365th of 25pw, you end up with a number of around 70twh of battery that is needed. We don't actually need that much of course since there are other options on the grid. But it just shows you that it could be doable and might be what we have in the field in a few decades. A few twh of battery on standby goes a long way and might just sit there fully charged most of the time.

ZeroGravitas 3y ago

The doubling of production is also what drives the learning curve cost decreases at a rate of 20% per doubling. Which is what has reduced battery costs by 90% over the last two decades and is widely predicted to continue. https://ourworldindata.org/learning-curve https://ourworldindata.org/learning-curve