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It'll be great when these battery cost reductions filter through to home batteries. At the moment a Tesla Powerwall 2.0 costs $6,700 for 13.5 kWh, so $496/kWh,

by pmuk 8y ago

It'll be great when these battery cost reductions filter through to home batteries. At the moment a Tesla Powerwall 2.0 costs $6,700 for 13.5 kWh, so $496/kWh, which is doesn't work as a financial investment. We've got a solar installation and so I have been considering getting a battery for either off peak to peak cost arbitration, or capturing excess solar energy for use at night. In the UK a Powerwall costs around £9,000 to £11,000 including additional hardware, taxes and installation. Based on some estimates (see below), at current prices I think you would be lucky to get a third of that back through energy bill savings. If the Powerwall sold at closer to its battery pack cost, it might be worth considering. Off peak to peak arbitration Peak cost of energy (£ per KWh) - £0.1573 Off peak cost of energy (£ per KWh) - £0.0815 Saving per KWh - £0.0758 Powerall 2 - maximum lifetime throughput - non solar uses (KWh) - 37800 [1] Lifetime power bill saving £2,865.62 Solar PV energy capture PV System Size (KWp) - 5.76 Solar irradiation - 986 Annual yield (KWh) - 5679 Annual energy exported to grid - assume 70% - 3976 Annual proportion that could be captured - estimate 50% - 1988 [2] Peak cost of energy (£ per KWh) - £0.1573 Annual saving - £312.66 [3] Warrant Period (years) - 10 Total saving over warranty period - £3,126.57 [1] https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_warranty_europe_1-5_english.pdf https://www.tesla.com/sites/default/files/pdfs/powerwall/pow... [2] In winter months, all solar energy could be captured, but in summer the panels will produce more than the Powerwall is able to store. [3] Doesn't factory in degradation over the period, which Tesla quotes at 80% capacity after 10 years

WhitneyLand 8y ago
What prevents cheap home lithium power? It seems easier for powerwall derivitives to become cheaper than solar because the % total cost of ownership not attributable to batteries is less. For example, it may not require a bunch of people on your roof, maybe less permit or zoning related costs, maybe less electrician labor, etc. Why couldn't a startup with a couple of EE's design something comparable or maybe even something with ease of installation innovations using commodity battery cells? Couldn't they buy cells in small batches online at first, paying notch or two higher than wholesale until they ramp up sales? Not sure how it couldn't start as a garage business for a clever engineer undergraduate and a clever sales/marketing/distribution person. I mean, people are already rolling their own as side projects right (without going into the practicality or safety of that, just in reference to the barriers to entry)?
- slfnflctd 8y ago
  This would be really nice to see. I started looking into emerging battery tech eight or ten years ago, and was really excited-- between approaches using compressed air storage (ha), liquid metal, saltwater, molten salt and new ways of using cobalt, I was convinced consumer price per kWh was about to be slashed in half by someone, somewhere, at least for stationary battery arrays. Since then, most of my enthusiasm about potential new products, bundles and kits that could be driven by this has steadily evaporated as consumer price per kWh for actual, usable power storage has more or less held steady. At this point I'm just as curious what's keeping it stuck there as I am about what we could do if it wasn't.
- zackmorris 8y ago
  Part of the problem is grid tie inverters. 1 kW used to cost about 10 times more than the equivalent 1 kW computer power supply, but prices have finally dropped to the point where they are comparable (roughly $100/kW): https://www.ebay.com/sch/i.html?_nkw=grid+tie+inverter https://www.ebay.com/sch/i.html?_nkw=grid+tie+inverter https://www.amazon.com/s?k=grid+tie+inverter https://www.amazon.com/s?k=grid+tie+inverter IMHO power converters like these are the future, because eventually we'll plug in all noisy sources of power from wind/solar/thermal into an inverter that accepts any voltage and plugs into the wall to provide 110 V AC. So roughly 12 of these (for a typical 100 amp system) would power the average home, meaning the inverter portion of a Powerwall should cost no more than $1200.
- pjc50 8y ago
  The cells themselves are the expensive bit. There have been one or two people doing it as recreational projects but obviously Tesla's vertical integration and large production run will win over the garage tinkerer. Not to mention that selling an unsafe product is a non starter. No, the interesting thing to me is why everyone forgot about the other chemistries like NiFe, which are cheaper but heavier - matters less for a fixed installation. Also I feel that proper net metering should be better than domestic batteries for the normal case. The only reason it isn't is regulatory spinelessness.
  - Tuna-Fish 8y ago
edent 8y ago
I'm in the UK and use a Moixa home battery with my solar panels. I agree that the tech is too expensive right now to break even - although I'm also dumping spare solar into my car's battery. https://shkspr.mobi/blog/2016/03/meet-maslow-the-uks-answer-to-teslas-powerwall/ https://shkspr.mobi/blog/2016/03/meet-maslow-the-uks-answer-...
- pmuk 8y ago
  Thanks, I'll take a look at Maslow and Moixa. We've got an electric car too, so I plan on getting a Zappi installed soon to push all surplus energy into the car battery. It automatically adjusts the charge rate to match the level of surplus being generated. https://myenergi.uk/ https://myenergi.uk/ I'm thinking of combining this with Economy 7 for charging the car at night when we've not had much sun.
mavhc 8y ago
I bought a 24kWh battery for £6500, came with free wheels to drive it around.
- mikeash 8y ago
  Can it power your house, though? (Serious question. I hear some of them can.)
  - alex_duf 8y ago
    The Nissan leaf is the only widely available one that can. In fact it's the chademo standard that allows it (the plug type) New generation cars are coming with that feature on other standards but as far as I'm aware, no other mass production vehicles are equipped with it yet.
  - mavhc 8y ago
    Yeah, it's a Leaf, but it costs way too much for a device to do so. Turns out CCS can't do V2H until v3 which isn't out yet. When I asked for a price in 2017 it was $2600
woodandsteel 8y ago
From what I have read, the problem is that there is a shortage of batteries for Powerwalls because Tesla's total demand for batteries is running ahead of its supply, and the company gives the priority to its autos, so Tesla is keeping the Powerwall prices high for now.

by pmuk 8y ago

WhitneyLand 8y ago

What prevents cheap home lithium power? It seems easier for powerwall derivitives to become cheaper than solar because the % total cost of ownership not attributable to batteries is less. For example, it may not require a bunch of people on your roof, maybe less permit or zoning related costs, maybe less electrician labor, etc. Why couldn't a startup with a couple of EE's design something comparable or maybe even something with ease of installation innovations using commodity battery cells? Couldn't they buy cells in small batches online at first, paying notch or two higher than wholesale until they ramp up sales? Not sure how it couldn't start as a garage business for a clever engineer undergraduate and a clever sales/marketing/distribution person. I mean, people are already rolling their own as side projects right (without going into the practicality or safety of that, just in reference to the barriers to entry)?

slfnflctd 8y ago
This would be really nice to see. I started looking into emerging battery tech eight or ten years ago, and was really excited-- between approaches using compressed air storage (ha), liquid metal, saltwater, molten salt and new ways of using cobalt, I was convinced consumer price per kWh was about to be slashed in half by someone, somewhere, at least for stationary battery arrays. Since then, most of my enthusiasm about potential new products, bundles and kits that could be driven by this has steadily evaporated as consumer price per kWh for actual, usable power storage has more or less held steady. At this point I'm just as curious what's keeping it stuck there as I am about what we could do if it wasn't.
zackmorris 8y ago
Part of the problem is grid tie inverters. 1 kW used to cost about 10 times more than the equivalent 1 kW computer power supply, but prices have finally dropped to the point where they are comparable (roughly $100/kW): https://www.ebay.com/sch/i.html?_nkw=grid+tie+inverter https://www.ebay.com/sch/i.html?_nkw=grid+tie+inverter https://www.amazon.com/s?k=grid+tie+inverter https://www.amazon.com/s?k=grid+tie+inverter IMHO power converters like these are the future, because eventually we'll plug in all noisy sources of power from wind/solar/thermal into an inverter that accepts any voltage and plugs into the wall to provide 110 V AC. So roughly 12 of these (for a typical 100 amp system) would power the average home, meaning the inverter portion of a Powerwall should cost no more than $1200.
pjc50 8y ago
The cells themselves are the expensive bit. There have been one or two people doing it as recreational projects but obviously Tesla's vertical integration and large production run will win over the garage tinkerer. Not to mention that selling an unsafe product is a non starter. No, the interesting thing to me is why everyone forgot about the other chemistries like NiFe, which are cheaper but heavier - matters less for a fixed installation. Also I feel that proper net metering should be better than domestic batteries for the normal case. The only reason it isn't is regulatory spinelessness.
- Tuna-Fish 8y ago

edent 8y ago

I'm in the UK and use a Moixa home battery with my solar panels. I agree that the tech is too expensive right now to break even - although I'm also dumping spare solar into my car's battery. https://shkspr.mobi/blog/2016/03/meet-maslow-the-uks-answer-to-teslas-powerwall/ https://shkspr.mobi/blog/2016/03/meet-maslow-the-uks-answer-...

pmuk 8y ago
Thanks, I'll take a look at Maslow and Moixa. We've got an electric car too, so I plan on getting a Zappi installed soon to push all surplus energy into the car battery. It automatically adjusts the charge rate to match the level of surplus being generated. https://myenergi.uk/ https://myenergi.uk/ I'm thinking of combining this with Economy 7 for charging the car at night when we've not had much sun.

mavhc 8y ago

I bought a 24kWh battery for £6500, came with free wheels to drive it around.

mikeash 8y ago
Can it power your house, though? (Serious question. I hear some of them can.)
- alex_duf 8y ago
  The Nissan leaf is the only widely available one that can. In fact it's the chademo standard that allows it (the plug type) New generation cars are coming with that feature on other standards but as far as I'm aware, no other mass production vehicles are equipped with it yet.
- mavhc 8y ago
  Yeah, it's a Leaf, but it costs way too much for a device to do so. Turns out CCS can't do V2H until v3 which isn't out yet. When I asked for a price in 2017 it was $2600

woodandsteel 8y ago

From what I have read, the problem is that there is a shortage of batteries for Powerwalls because Tesla's total demand for batteries is running ahead of its supply, and the company gives the priority to its autos, so Tesla is keeping the Powerwall prices high for now.