  Smart meters are key elements for the operation of smart grids. By providing
near realtime information on the energy consumption of individual users, smart
meters increase the efficiency in generation, distribution and storage of
energy in a smart grid. The ability of the utility provider to track users
energy consumption inevitably leads to important threats to privacy. In this
paper, privacy in a smart metering system is studied from an information
theoretic perspective in the presence of energy harvesting and storage units.
It is shown that energy harvesting provides increased privacy by diversifying
the energy source, while a storage device can be used to increase both the
energy efficiency and the privacy of the user. For given input load and energy
harvesting rates, it is shown that there exists a trade-off between the
information leakage rate, which is used to measure the privacy of the user, and
the wasted energy rate, which is a measure of the energy-efficiency. The impact
of the energy harvesting rate and the size of the storage device on this
trade-off is also studied.
