Tesla Powerwall: Engineering Analysis

[anorlunda]

A side question, could one hook one of these up with a generator and charge with the unused power?

Sure. I imagine that batteries in combination with on site generation are very attractive.

Remember that not all locations have net metering where you sell excess power back to the utility, nor are all users on the grid. On-site energy storsge is most attractive to those users.

I think the solar/storage combination is attractive. Once you have a solar installation, you already bought the inverter, mandatory grid interface (if any), and installation labor. The incremental cost to add additional panels is small. Combine that with the cost of adding battery storage, and the economics are compelling.

Where net metering is available, the grid acts as your storage battery at no charge. That is why I think net metering is not sustainable.

 

[shanaya]

i have question that how can we increase the output voltage 90vdc to 200v if we are having the input voltage 220v ac?

 

[anorlunda]

The DC to AC inverter will boost the voltage. It has an internal transformer.

 

[mheslep]

By the way, the world's biggest utility battery installation is in Fairbanks Alaska.

That facility was build with Ni-Cads in 2006 (45 MW, 4 MWh). The new largest in N. America is li-ion based and eight times larger, http://www.greentechmedia.com/articles/read/The-Biggest-Battery-in-North-America-Gets-Unveiled-By-SCE-Today in California.

 

[mheslep]

They are required to pay whatever it takes to buy all the energy needed to satisfy the demand, not matter what the price.

Also, in many places utilities are required by the state to buy a quota of certain types of power, specifically renewable power (aka RPS).

 

[anorlunda]

That facility was build with Ni-Cads in 2006 (45 MW, 4 MWh). The new largest in N. America is li-ion based and eight times larger, 32 MWh, in California.

Thank you mheslep, I was not aware of the California installation. In another recent thread, Batteries for utility storage, I found news of a battery facility under construction in Austrailia with 50 MW. 300 MWh . Maybe we'll see more wide spread use of utility batteries in the future.

I'm curious about choice of chemistry. For utility applicaitons, volumetric or mass energy density sounds unimportant. Their lifetime measured in cycles may be similar. Is it simply $/MWH that determines the choice?

Also, in many places utilities are required by the state to buy a quota of certain types of power, specifically renewable power (aka RPS).

But batteries are not an energy source, just energy storage. Do purchases of battery power count as renewable? It sounds complex, because you have to figure the source of energy used to charge the battery.

I would also add, that the location of the generation is sometimes also a requirement. For example, Manhattan Island in NYC, where some fraction of reserves must be on-island.

 

[mheslep]

Is it simply $/MWH that determines the choice?

amortized capital cost of storage $/MWh, efficiency, and $/MW, i.e. cost for storage, cost of wasted generated energy, and cost of rate of charge/discharge. The last may or may not add to the total cost.