Concerns about privacy have risen with most forms of wireless use. The advent of EZ-Pass toll systems as a way to automate collections and eliminate cashiers immediately brought forth the scenario of time-stamped entry & exit data from a toll road being shared with authorities if it indicates a driver was speeding on documented occasions. It was discovered that cities like New York "ping" transponders at choke points, not to charge tolls, but to count vehicles for traffic flow monitoring. Such "where & when" stats could be shared with police. The New York State Department of Transportation (NYSDOT) "has silently scanned tags for years to monitor the flow of New York City traffic. But...the agency scrambles the serial numbers to anonymize vehicles and their owners." [240, 240a] The fact that E-ZPasses can be used as a tracking device outside of toll payment, is not disclosed in the terms and conditions.
Retail Analytics lets stores track customers near or in the store using their cell phones much as websites can track the clicks of their customers.
Smart Meters Aid & Abet the Invasion of Privacy.
A paper outlining cyber vulnerability and other issues arising with the
worldwide deployments of smart meters  noted that in 2008 Dutch courts had determined that "fine-grained central data collection by smart meters to be an unacceptable infringement of citizens’ privacy and security, following opposition by the Dutch consumers’ association." [241a]
National Grid asserts to maintaining "robust security to ensure data is safe and consumers are protected. All data transmitted via the Itron® smart meters is encrypted to ensure the privacy of customer information."  in referring to the meters they are using in the Worcester Pilot of 15,000 customers. The new Landis & Gyr® meters used in Pennsylvania Electric's system encrypt data transmissions also  so we can rest assured that at least the neighborhood geek will not be able to "read" our meters remotely with a digital receiver.
Patricia Burke of HaltMAsmartmeters.org has discovered a privacy concern regarding the National Grid smart meter pilot:
National Grid purchased demographic, lifestyle, and buying behaviour data (financial) on pilot participants from InfoGroup and Core Logic and matched to Pilot accounts by combinations of address, phone number, and/or customer name.
The relevant data is shown in the Interim Evaluation Report to the DPU, published on Feb. 24, 2916. 
Aside from data collected by smart meters and its use/misuse by utilities
and third party "partners" (including government agencies) we have seen the ease with which our banking and credit info can be stolen from trusted institutions with "solid, foolproof" security measures in place. Even with data being sent only to the utility on its own private network the question becomes"How secure is our data once it is stored on the utility's systems?"
The Department of Energy proffered a voluntary code of conduct governing privacy of data from smart meters [9a] and President Obama, in January, 2015, announced the release of the final concepts and principles for a Voluntary Code of Conduct (VCC) governing utilities, government agencies and any other parties regarding the collection, storage, dissemination or sharing of utility customers' private data, that is, the US government's Data
But the value of customer analytics may be greater than the cost of electric power consumed: It is now used to make the smart grid smarter and more efficient but could eventually be sold to retailers and others - with customer consent - in exchange for a discount, for example. "The roll-out of AMI in many utility service territories has produced large amounts of customer generated data, and utilities are seeking opportunities to maximize its value." 
Utilities are eager about the prospects: "Dr. Stephen Pratt, Chief Technical Officer for CenterPoint Energy, stated the following during an
“We have an entire organization that’s gotten behind data as an asset
… We get a lot of data. We do 221,000,000 meter reads a day …
We can do nothing with that data, or we can mine that data
Utilities will 'swear' their smart meters are not surveillance devices but the very thing a meter does, collecting granular data about energy use at a specific home or site by specific persons on a continuous, ongoing basis, fits the definition of surveillance. While specific activities are not recorded they can be inferred by analyzing amounts of energy use at specific times of day. 
Most would agree a smart meter's ability to detect tampering by customers is a good thing as well as a meter being able to send alarms to
the utility if a customer's service is overheating. But a spokesman for PECO (Pennsylvania Electric), which has practically completed 1.7 million SM installations gloats, "Now that the system is in, we can really start to extract the value," said Dickens. "There's so much data there that we have to sit down and figure out how to mine it." The Landis & Gyr® models that replaced the 186,000 Sensus® meters changed out in 2012 to avoid risk of fire have built in GPS; The device awakens on installation and reports its GPS coordinates to the PECO system.
“I think the data is going to be worth a lot more than the commodity that’s being consumed to generate the data,” said Miles Keogh, director of grants and research at the National Association of Regulatory Utility Commissioners.
All sorts of inferences about people’s private lives are potentially available from detailed energy consumption data. The number of people inside a house. Daily routines. Degree of religious observance. Household appliance usage. Even, according to two German hackers, what’s on the television, given a fast enough meter refresh rate.
“Very sensitive information can be revealed about homes, and homes are the most sacred privacy environment,” said Nancy King, an Oregon State University business law and ethics academic who’s studying smart meter deployments.