Tesla Motors to Unveil Home and Utility Batteries April 30
bloomberg.com
bloomberg.com
Very interested in the announcement, pricing etc.
An alternative is to automatically disconnect your home from the grid in that situation, rather than disabling the PV. This is referred to as intentional islanding. (Although I suppose that could be disallowed in some jurisdictions, for no good reason that I can think of. At the very least though, you should be able to manually disconnect once the anti-islanding has kicked in, and then fire the PV and/or battery-powered inverter back up.) Depending on your equipment you may still have to shut down before reconnecting to the grid, once grid power is back up. (Depends on whether your inverter is capable of re-synchronizing with the grid, and again I suppose based on regulations in your jurisdiction.)
These batteries might help achieve some of this redundancy for an independent community grid, but the total installed battery+generation capacity would have to far exceed peak demand.
Another thing the grid connection gets you is the ability to charge your battery with cheap, but intermittent renewable electricity being generated at distant wind farms.
You also still have the problem of building, financing, and maintaining the local power distribution infrastructure in your community.
It would be interesting a) What the payback period is on a strategy where you charge when the spot price is low, and discharge when high, and b) How much installed battery capacity would be required to eliminate this arbitrage? i.e. what MWh of installed battery capacity would flatten the 24 hour across-grid demand cycle.
Then the price will rise at night and lower during the day.
Anyone who buys one of these just for time-arbitraging electricity is taking a pretty big risk.
This smells of the Newman/Krammer bottle deposit arbitrage scam.
The objective would be charge the battery up at night from the grid, and then use that power during the day + your solar power, when power is expensive.
Net metering is an accounting trick which lets you treat the grid as a big storage battery. My house "charges up" this battery during the day by running the meter backward; then I can "draw down" the battery at night, when my panels are inactive.
If I had a literal storage battery at home, the economics would work exactly the same way: but instead of externalizing the cost of the battery onto the public utility, I'd be paying the cost myself by purchasing the battery.
Solar power, on top of that, will be a bonus.
For the summer, California E-6 Residential rates are $.32/kWh during peak times, $0.13/kWh during off peak. If your house is using, say, 4 kW, for 5 hours during peak - then that 20 kWh will cost save you 20 * ($0.32-$0.13) = $3.80/day in power costs, approx $115/month. Do that for 4 months/year ,that's $460/year. With a 5 year life, that battery would need to be less than $2300 to come out even.
http://cleantechnica.com/2014/09/05/teslas-gigafactory-may-h... suggests that $100/kWh is in the ballpark - so this might make sense right out the door.
There should be savings there as well!
You could argue using battery electricity in stead of bringing in grid electricity is functionally equivalent to selling it to the grid, both in terms of pricing incentives, and the effect on the grid – in the same way that people are discussing being able to switch fridges on and off minute by minute as being equivalent to building grid generators which can be switched on and off on that timescale.
How feasible is it that the majority of households could have a massive home-battery installed in terms of natural resources? It seems like a lot of rare earth materials to build so many big batteries.
From Wikipedia: However, according to a 2011 study conducted at Lawrence Berkeley National Laboratory and the University of California Berkeley, the currently estimated reserve base of lithium should not be a limiting factor for large-scale battery production for electric vehicles, as the study estimated that on the order of 1 billion 40 kWh Li-based batteries could be built with current reserves.[85] Another 2011 study by researchers from the University of Michigan and Ford Motor Company found that there are sufficient lithium resources to support global demand until 2100, including the lithium required for the potential widespread use of hybrid electric, plug-in hybrid electric and battery electric vehicles. The study estimated global lithium reserves at 39 million tons, and total demand for lithium during the 90-year period analyzed at 12–20 million tons, depending on the scenarios regarding economic growth and recycling rates.[1]
Of course, lithium isn't the only element we can use to make batteries.
Note, I'm not making a claim one way or the other on the feasibility, just stating that resources don't appear to be a limiting factor for the next ~life-time.
Lithium-ion cells actually don't necessarily require any rare earth metals at all. For instance, the batteries Tesla currently uses for their cars are made up of lithium, nickel, cobalt, aluminum, and carbon, none of which qualify as rare earth elements.
There's a lot of lithium, but it's unlikely there is enough Lithium in the world to provide everyone with large home batteries.
But at that scale you don't have to use lithium anyway. When it comes to grid or off-grid storage, you don't need the best energy density as cost per watt-hour is probably the most important factor and there are already other chemistries on the market that will work just fine with many more on the way. Sodium or Aluminium based batteries seem particularly promising.
Like how Tesla Model S's get their owners access to luxury, HOV lanes, and public environmental bragging rights (presumably the buyers of a $100k car aren't trying to save money on gas).
Otherwise, like some have noted, why wouldn't the utilities themselves do the storage and avoid the round-trip power transmission losses?
The thing is, in the US, power outages are pretty rare and fixed pretty quickly, so bridging outages doesn't seem like a major selling point. If the customer really is the homeowner, I'm still wondering what the big life-value-add is. It's not like home battery storage market has a luxury segment that can be initially targeted as the Model S is in the car market. And
And I don't think that Elon is targeting geeks who want to set up power arbitrage schemes in their homes.
EDIT: final point added.
In South Africa we're having rolling blackouts called "load shedding" because we don't have enough power. Exactly why is a long and obviously controversial story, but in short: Mega projects that were supposed to fill in the gaps are being delayed, maintenance on existing infrastructure was delayed in the hope that the new projects would come online in time, but that's now causing cascading failures and maintenance cannot be avoided any longer, causing even more outages..
The blackouts are zoned and 2.5 hours at a time. Here's Cape Town's map, for example: http://ewn.co.za/assets/loadshedding/capetown.html
So we don't have grid power 24/7 anymore and our electricity prices (that used to be some of the cheapest in the world) are now skyrocketing. So I would imagine that many many people here might be in the market for something like this at the right price.
Totally agree that there is a big market here for the Tesla home batteries, depending on the cost vs capacity. I am definitely in the market.
I've actually been looking into playing with some LiFePO4 batteries and trying to see how big of a UPS you can build for, say, R5000 or R10000. LiFe batteries have longer lifetimes, are safer (less likely to catch fire or explode), are less finicky about how they get charged (more like lead-acid), seem to be potentially a bit cheaper, easier to use in multi-cell configurations (cell-balancing issue related), etc. You can also source or sink more current, so faster to charge/discharge. Downside is 14% less energy density which is why they don't get used in laptops or smartphones and (in Tesla's case) sometimes also not in cars. But that's not much of a downside for (off-)grid storage..
Pretty sure there's a gap in the market there just waiting for someone to jump into. And once you already have a giant battery it is probably that much easier to convince yourself of covering your roof in solar panels, getting a gas stove and disconnecting yourself from the grid entirely :)
A system like this costs 5-10 grand.
I wonder if these home batteries would be a less expensive alternative.
If the big wind power people start buying these, it's real.
Not that a cheaper, more energy dense UPS isn't already a win but the article keeps focusing on the fact that the product is a battery, not what it will actually be used for.