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I have been speaking with Solar City's commercial division about doing large grid-tied solar projects with Tesla batteries in one of USA largest cities and have

I have been speaking with Solar City's commercial division about doing large grid-tied solar projects with Tesla batteries in one of USA largest cities and have $100M in projects under development. These batteries aren't going to power your home at night, nor should they as electricity rates at night are dirt cheap (comparatively) when people aren't at work, in factories and in bed sleeping. These batteries are going to be performing grid marketplace arbitrage and some governments and utilities are providing amazing incentives to do so. (Currently the incentives require the batteries to be tied to solar.) There are two pieces of your electricity bill (I'm simplifying here) 1) the electricity charge (EC) and 2) the transmission charge (TC). The EC is calculated by how many kWh you use during each (peak/off-peak) period of the day and the TC is calculated by your max grid demand during your largest 15 minutes for the month. Tesla Batteries are not just about the batteries, the system calculates how to remove kWh demand from peak hours by pulling power from batteries and then recharging during off-peak hours. This covers the EC cost reduction. To reduce TC costs the system calculates your peak load over the given month and tries to turn it from a "mountain range" (with many peaks) to a "platou". You pay your TC for the tallest mountain for the month. At first the system doesn't know that much about your usage profile and will just focus on the largest peak demand 15 minute intervals. Then over time it will learn more about your usage patterns and slowly platou your grid demand. At the end of the day it is going to be much more cost effective and efficient to have a distributed grid with thousands of solar arrays and batteries than build out large billion dollar gas fired turbines or even wind turbines.

driverdan 12y ago
This is the answer. Commercial power penalizes you for having a large difference between your peak use and continuous use. If you can eliminate peaks using batteries you can eliminate this penalty. You can also recharge the batteries during off hours to cut costs further.
- deleted 12y ago
  [deleted]
- danielweber 12y ago
  Unless you have a particular reason to worry about your connection to the grid, it's better to use demand management than batteries. Let's take a Tesla S battery. It costs $30,000 [1]. It has a capacity of 85KWh, which lasts 265 miles. [2] The battery is down to 80% life after 100K miles [3], which is 377 cycles. Say you fill up the battery at 5 cents/KWh and sell it at 20 cents/KWh. You've made $12.75. After 377 cycles, you've made almost $5000. You still have life in those batteries, but they are going to keep on getting worse, and the efficiency of energy in/energy out will start falling as well. Once you hit 40% they are probably useless. You might be able to run that $5000 two or three more times before you hit that. You could only barely use the batteries to prolong their life. But you spent $30,000 on them! That's a lot of capital costs for something that isn't doing anything. And Li-Ions will gradually lose capacity even if you don't use them and store them in ideal conditions. There are certainly efficiencies of switching from a car-bound battery to a stationary battery, although a lot of people posting on this page are talking about hooking up a car to do price arbitrage. [1] http://my.teslamotors.com/it_CH/forum/forums/battery-replacement-cost http://my.teslamotors.com/it_CH/forum/forums/battery-replace... and watch how hard it is for the guy to get an answer [2] https://www.google.com/search?q=tesla+car+battery+capacity&oq=tesla+car+battery+capacity&safe=active&ssui=on https://www.google.com/search?q=tesla+car+battery+capacity&o... [3] http://www.plugincars.com/tesla-roadster-battery-life-study-85-percent-after-100000-miles-127733.html http://www.plugincars.com/tesla-roadster-battery-life-study-... don't just read the headline
  - ethbro 12y ago
    Does anyone want to comment on flow batteries? E.g. http://www.cbc.ca/news/technology/organic-battery-hailed-as-cheap-renewable-energy-solution-1.2489300 http://www.cbc.ca/news/technology/organic-battery-hailed-as-... I assume the primary issue now is cost, but if you can decouple the reaction -> electricity engine from the reactants to a greater degree, then it sounds attractive? I imagine increasing storage tankage is a much easier problem to solve than increasing energy density.
  - mhandley 12y ago
    I would expect the car is a much more harsh environment for the battery than my house. I'm not talking about vibration or temperature, though those matter, but electrical demand. A model S has a 310kW motor. Nothing in my house comes anywhere close to demanding 310kW. Of course the Tesla will rarely require the full 310kW, but its charge and recharge cycles are at the mercy of your driving. You could smooth out the peaks in my home demand with probably just 10kW. Perhaps smooth out many of my neighbours peaks with 50kW. But my point is that there are no hard bounds that the battery needs to satisfy, unlike in a car when you have to supply the drive current or sink the brake current. You can tune a home battery's charge/discard cycles for maximum battery life rather than maximum performance. I don't have data for how much difference that would make to battery life, but I would guess it may be significant.
nkg 12y ago
smooth.
jackreichert 12y ago
This is also the missing piece to move over to a more renewable energy source. Coal is on demand. If there is a need for more, you can spin up more factories, and many site waiting just for this. Most renewable energies are reliable, but over longer periods of time. With a way to store energy, and have it dormant in the grid waiting to be used, this creates the surplus needed so we can switch to solar and wind and be able to rely on output.
- bdcs 12y ago
  Your point is correct, but the details are wrong: coal (and nuclear) provide so-called "baseload" power, while natgas and hydro provide "peak" power (this is why natgas plants are called peakers). Coal has a very long spin-up (and spin-down) time. If you've studied process control, the first-order time delay is on the order of hours to days. Natural gas and hydro have time constants of ca. minutes. Moreover to your point, batteries have very short time constants (but a plethora of of other problems).
  - Florin_Andrei 12y ago
    So, for coal, is it just because of thermal inertia? The size of the whole thing? Do they need to load the coal in a specific way?
    - stcredzero 12y ago
      That's very likely due to size. Things like powerplants get more efficient as they get larger. (And as they get more complex by piling on more optimizing subsystems.)
    - toomuchtodo 12y ago
      Thermal inertia. Boilers have to be brought up to temp, and do not take well to throttling like a combined cycle natural gas plant.
    - WalterBright 12y ago
      For coal, I think it is because of the large turbines used. They have to be brought up to temperature gradually because they are very large precision made hunks of metal.
oconnore 12y ago
I was with you until you said that distributed energy is more efficient than large scale energy. A large scale hydroelectric, battery, or wind plant will be far more efficient than distributed energy in the home. Solar may benefit from capitalizing on under utilized residential real estate, but absent that incentive, a large solar plant will also be more efficient than a distributed per home grid due to standardized install and maintenance, larger inverters, and optimized layout (most home systems are non tracking).
- criley2 12y ago
  You're not counting transmission loss, something that distributed systems avoid. Central systems are more efficient but also must lose efficiency to transmit the power over distance.
  - lukifer 12y ago
    As a naive layman, I'd be very curious to see numbers on inefficiencies of non-tracking panels vs. typical transmission loss.
    - oconnore 12y ago
      25-35% more efficient for single axis tracking panels vs. non tracking. Distribution losses are ~6%. http://en.wikipedia.org/wiki/Solar_tracker#Basic_concept http://en.wikipedia.org/wiki/Solar_tracker#Basic_concept http://energyinformative.org/solar-panel-tracking-systems http://energyinformative.org/solar-panel-tracking-systems
  - oconnore 12y ago
    I'm ignoring it because it's mostly irrelevant (6% total, ~1% for transmission). If it weren't, we would not have an electric grid. http://www.eia.gov/tools/faqs/faq.cfm?id=105&t=3 http://www.eia.gov/tools/faqs/faq.cfm?id=105&t=3 https://en.wikipedia.org/wiki/Electric_power_transmission#Losses https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...
smoyer 12y ago
Yep ... This idea has been around for a long time (Hydrokinetix was building ETS systems in the '80s) but a great battery will allow the technology to go mainstream. It's cool to hear that you've got such a backlog of orders! Good luck!
api 12y ago
As I understand it the big problem is the "duck curve," the spike in demand that occurs immediately as the sun sets when there's a lot of solar. If the batteries could smooth that out, that'd be pretty huge in helping solar adoption.
the_ancient 12y ago
>> should they as electricity rates at night are dirt cheap I dont know where you are but my electric rate is the same night or not... I pay the exact same rate 24/7 I do not have demand based pricing which is reserved for business customers or persons consuming a crap load more power than I. >>At the end of the day the Power Companies are doing their level best to penalize home use Solar, they want to charge home owners through the nose if they "sell" power back to the grid eliminating any costs savings and in come cases making a roof top solar project more expensive than just buy power from the mafia err power companies. Distributed non-grid power should be the goal, Grid power needs to be phased out.
- jstrom 12y ago
  That's not necessary malicious on the part of the power company. At a previous job, we built a system for a company that prepared batteries through multiple charge/discharge phases. During a discharge, the power was pushed back onto the grid. The major challenge was matching the waveform of the grid power (occasional spikes confusing the zero-crossing, drift on the timer elements etc.). If you don't, it reduces the efficiency of the power company's transformer leading to replacement with a larger one, or damage due to the excess heat. You can imagine they're going to recover that expense from somewhere (and you and your dirty sine wave are pretty clearly at fault). I would expect the home systems to be less precise than our industrial client's equipment.
- lotsofmangos 12y ago
  A lot of UK homes have storage heaters that are powered at a cheaper rate at night on an off-peak circuit.
  - laurencerowe 12y ago
    I never got the point of storage heaters. They're completely useless in the evening when you want heating. Much of the heat escapes when they're on overnight (while in bed so little need for it) and the rest during the day while you're at work.
    - 12y ago
afarrell 12y ago
Do you operate in one particular ISO or multiple?

driverdan 12y ago

This is the answer. Commercial power penalizes you for having a large difference between your peak use and continuous use. If you can eliminate peaks using batteries you can eliminate this penalty. You can also recharge the batteries during off hours to cut costs further.

deleted 12y ago
[deleted]
danielweber 12y ago
Unless you have a particular reason to worry about your connection to the grid, it's better to use demand management than batteries. Let's take a Tesla S battery. It costs $30,000 [1]. It has a capacity of 85KWh, which lasts 265 miles. [2] The battery is down to 80% life after 100K miles [3], which is 377 cycles. Say you fill up the battery at 5 cents/KWh and sell it at 20 cents/KWh. You've made $12.75. After 377 cycles, you've made almost $5000. You still have life in those batteries, but they are going to keep on getting worse, and the efficiency of energy in/energy out will start falling as well. Once you hit 40% they are probably useless. You might be able to run that $5000 two or three more times before you hit that. You could only barely use the batteries to prolong their life. But you spent $30,000 on them! That's a lot of capital costs for something that isn't doing anything. And Li-Ions will gradually lose capacity even if you don't use them and store them in ideal conditions. There are certainly efficiencies of switching from a car-bound battery to a stationary battery, although a lot of people posting on this page are talking about hooking up a car to do price arbitrage. [1] http://my.teslamotors.com/it_CH/forum/forums/battery-replacement-cost http://my.teslamotors.com/it_CH/forum/forums/battery-replace... and watch how hard it is for the guy to get an answer [2] https://www.google.com/search?q=tesla+car+battery+capacity&oq=tesla+car+battery+capacity&safe=active&ssui=on https://www.google.com/search?q=tesla+car+battery+capacity&o... [3] http://www.plugincars.com/tesla-roadster-battery-life-study-85-percent-after-100000-miles-127733.html http://www.plugincars.com/tesla-roadster-battery-life-study-... don't just read the headline
- ethbro 12y ago
  Does anyone want to comment on flow batteries? E.g. http://www.cbc.ca/news/technology/organic-battery-hailed-as-cheap-renewable-energy-solution-1.2489300 http://www.cbc.ca/news/technology/organic-battery-hailed-as-... I assume the primary issue now is cost, but if you can decouple the reaction -> electricity engine from the reactants to a greater degree, then it sounds attractive? I imagine increasing storage tankage is a much easier problem to solve than increasing energy density.
- mhandley 12y ago
  I would expect the car is a much more harsh environment for the battery than my house. I'm not talking about vibration or temperature, though those matter, but electrical demand. A model S has a 310kW motor. Nothing in my house comes anywhere close to demanding 310kW. Of course the Tesla will rarely require the full 310kW, but its charge and recharge cycles are at the mercy of your driving. You could smooth out the peaks in my home demand with probably just 10kW. Perhaps smooth out many of my neighbours peaks with 50kW. But my point is that there are no hard bounds that the battery needs to satisfy, unlike in a car when you have to supply the drive current or sink the brake current. You can tune a home battery's charge/discard cycles for maximum battery life rather than maximum performance. I don't have data for how much difference that would make to battery life, but I would guess it may be significant.

nkg 12y ago

smooth.

jackreichert 12y ago

This is also the missing piece to move over to a more renewable energy source. Coal is on demand. If there is a need for more, you can spin up more factories, and many site waiting just for this. Most renewable energies are reliable, but over longer periods of time. With a way to store energy, and have it dormant in the grid waiting to be used, this creates the surplus needed so we can switch to solar and wind and be able to rely on output.

bdcs 12y ago
Your point is correct, but the details are wrong: coal (and nuclear) provide so-called "baseload" power, while natgas and hydro provide "peak" power (this is why natgas plants are called peakers). Coal has a very long spin-up (and spin-down) time. If you've studied process control, the first-order time delay is on the order of hours to days. Natural gas and hydro have time constants of ca. minutes. Moreover to your point, batteries have very short time constants (but a plethora of of other problems).
- Florin_Andrei 12y ago
  So, for coal, is it just because of thermal inertia? The size of the whole thing? Do they need to load the coal in a specific way?
  - stcredzero 12y ago
    That's very likely due to size. Things like powerplants get more efficient as they get larger. (And as they get more complex by piling on more optimizing subsystems.)
  - toomuchtodo 12y ago
    Thermal inertia. Boilers have to be brought up to temp, and do not take well to throttling like a combined cycle natural gas plant.
  - WalterBright 12y ago
    For coal, I think it is because of the large turbines used. They have to be brought up to temperature gradually because they are very large precision made hunks of metal.

oconnore 12y ago

I was with you until you said that distributed energy is more efficient than large scale energy. A large scale hydroelectric, battery, or wind plant will be far more efficient than distributed energy in the home. Solar may benefit from capitalizing on under utilized residential real estate, but absent that incentive, a large solar plant will also be more efficient than a distributed per home grid due to standardized install and maintenance, larger inverters, and optimized layout (most home systems are non tracking).

criley2 12y ago
You're not counting transmission loss, something that distributed systems avoid. Central systems are more efficient but also must lose efficiency to transmit the power over distance.
- lukifer 12y ago
  As a naive layman, I'd be very curious to see numbers on inefficiencies of non-tracking panels vs. typical transmission loss.
  - oconnore 12y ago
    25-35% more efficient for single axis tracking panels vs. non tracking. Distribution losses are ~6%. http://en.wikipedia.org/wiki/Solar_tracker#Basic_concept http://en.wikipedia.org/wiki/Solar_tracker#Basic_concept http://energyinformative.org/solar-panel-tracking-systems http://energyinformative.org/solar-panel-tracking-systems
- oconnore 12y ago
  I'm ignoring it because it's mostly irrelevant (6% total, ~1% for transmission). If it weren't, we would not have an electric grid. http://www.eia.gov/tools/faqs/faq.cfm?id=105&t=3 http://www.eia.gov/tools/faqs/faq.cfm?id=105&t=3 https://en.wikipedia.org/wiki/Electric_power_transmission#Losses https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...

smoyer 12y ago

Yep ... This idea has been around for a long time (Hydrokinetix was building ETS systems in the '80s) but a great battery will allow the technology to go mainstream. It's cool to hear that you've got such a backlog of orders! Good luck!

api 12y ago

As I understand it the big problem is the "duck curve," the spike in demand that occurs immediately as the sun sets when there's a lot of solar. If the batteries could smooth that out, that'd be pretty huge in helping solar adoption.

the_ancient 12y ago

>> should they as electricity rates at night are dirt cheap I dont know where you are but my electric rate is the same night or not... I pay the exact same rate 24/7 I do not have demand based pricing which is reserved for business customers or persons consuming a crap load more power than I. >>At the end of the day the Power Companies are doing their level best to penalize home use Solar, they want to charge home owners through the nose if they "sell" power back to the grid eliminating any costs savings and in come cases making a roof top solar project more expensive than just buy power from the mafia err power companies. Distributed non-grid power should be the goal, Grid power needs to be phased out.

jstrom 12y ago
That's not necessary malicious on the part of the power company. At a previous job, we built a system for a company that prepared batteries through multiple charge/discharge phases. During a discharge, the power was pushed back onto the grid. The major challenge was matching the waveform of the grid power (occasional spikes confusing the zero-crossing, drift on the timer elements etc.). If you don't, it reduces the efficiency of the power company's transformer leading to replacement with a larger one, or damage due to the excess heat. You can imagine they're going to recover that expense from somewhere (and you and your dirty sine wave are pretty clearly at fault). I would expect the home systems to be less precise than our industrial client's equipment.
lotsofmangos 12y ago
A lot of UK homes have storage heaters that are powered at a cheaper rate at night on an off-peak circuit.
- laurencerowe 12y ago
  I never got the point of storage heaters. They're completely useless in the evening when you want heating. Much of the heat escapes when they're on overnight (while in bed so little need for it) and the rest during the day while you're at work.
  - 12y ago

afarrell 12y ago

Do you operate in one particular ISO or multiple?