  The current trend towards more renewable and sustainable energy generation
leads to an increased interest in new energy management systems and the concept
of a smart grid. One important aspect of this is local energy trading, which is
an extension of existing electricity markets by including prosumers, who are
consumers also producing electricity. Prosumers having a surplus of energy may
directly trade this surplus with other prosumers, which are currently in
demand. In this paper, we present an overview of the literature in the area of
local energy trading. In order to provide structure to the broad range of
publications, we identify key characteristics, define the various settings, and
cluster the considered literature along these characteristics. We identify
three main research lines, each with a distinct setting and research question.
We analyze and compare the settings, the used techniques, and the results and
findings within each cluster and derive connections between the clusters. In
addition, we identify important aspects, which up to now have to a large extent
been neglected in the considered literature and highlight interesting research
directions, and open problems for future work.
