Saving Money by Understanding Demand Charges on Your Electric Bill, Cover Page Demand–related charges usually represent 30 to 70 percent of most commercial customers' electric bills.
The sort of demand charge cited in that article is fairly rare. The typical demand charge simply looks at the peak demand of the customer, regardless of when that occurs. Managing demand charges is a key business proposition for "Smart Grid" applications. For example, one of Comverge's offerings coordinates when HVAC compresses turn on, sequencing them to eliminate spikes. The challenge in trying to manage the sort of "coincident peak" demand charges described in the article is to predict exactly when the system peak demand will occur. Under one plan (now replaced) in the UK, all of the transmission charges for the month were allocated based on a customer's use during the top three, non-consecutive hours. This rule spawned a service business of forecasting those hours; companies even guaranteed that they could hit two of the three. Of course, the more people who attempt to shift usage from a peak hour to an adjacent hour, the more likely it is that the peak itself will move. Having on-site storage combined with good software to control energy usage could certainly save commercial customers a lot of money. If residential customers were ever charged for their power use on a sensible tariff design, then they could, too.
In september the first commercial EES "battery park" will be connected to the grid in Germany. Initial subsidies helped, but it's intended to operate cash positive in the free market. Rated power is 5 MW and it has capacity of 5 MWh. "The fully automated battery park sets new standards in many respects: For the first time in Europe, a battery will provide primary frequency regulation without back-up by a conventional power plant. Also for the first time a battery park is being operated commercially and will - following an initial innovation grant - earn its keep through market proceeds. Another unique feature is the performance of the park's Lithium-ion cells is guranteed for 20 years by cell producers Samsung SDI." Source and more pictures: Younicos: Europe’s first commercial battery park!
What Does A SolarCity/Tesla Storage System Cost? Someone shopped SolarCity for a 10 kWh residential battery. It leases for 10 years with $1500 and $15/month. Assuming a 9% discount, this has a present value of $2684. If both SolarCity and Tesla have a 30% mark up, then the cost to SolarCity must be $2008 and to Tesla $1588. I wonder if Tesla really has this down to a cost of $159/kWh.
New article about stationary storage potential for Tesla. Tesla Motors Inc (NASDAQ:TSLA), SolarCity Corp(NASDAQ:SCTY) News Analysis: Tesla Motors Inc Could Soon Be The Nation's Top Energy-Storage Vendor