Differences between P2P trading and PPAs. As already seen above, P2P trading is a bilateral electricity trade between prosumers. In contrast, by the definition of PPA, PPA is a unilateral electricity trade contract in a one-way from renewable power producer (seller) to final consumer or an intermediary, such as a supplier (buyer). A distinct cast of either generator or consumer is defined under a PPA, i.e. the contractors under a PPA must be either generator or consumer, which is completely different from the P2P case: in P2P trading, each contacting party can be both generator and consumer, although this does not always have to be the case. Besides this, there are a number of differences between P2P trading and PPAs. First, the capacity of renewable power plants under a PPA is likely to be much larger, for instance a few MWs capacities are commonly seen, compared to that of under P2P which can include small-scale plant less than 10 kW capacity. Though small-scale plants like less than 10 kW can be a contractor of PPA in theory, an actual application of such case is rarely seen unless these small plants are aggregated by an aggregator, typically large private companies. Similarly, the consumer side of a PPA is most likely to be a large organization and not an individual household. Once again, this is a highly distinct feature compared to the P2P trading case, which theoretically can accommodate any type of consumers from individual household to a large organization. However, this may change in the future, with PPAs offered also to smaller consumers. On the other hand, some P2P trading pilot schemes also include more medium-sized renewable energy plants that reached the past-FIT age. Second, the duration of contracts for electricity trading is significantly different between P2P trading and PPAs, i.e. the duration of a PPA is normally on a yearly-basis, which can last 10 years or more. In contrast, the duration of a P2P trading contract execution can vary from few seconds to few hours, days, weeks depending upon the situation, but very unlikely to be on a yearly-basis. However, the P2P ‘framework’ contract between the participating generators, prosumers, and consumers to sell and buy electricity at a certain price and conditions can be concluded for several months, a year or two, and can be automatically renewing. The purpose of PPAs is obviously to provide private/public organizations with a means to procure renewable electricity over the longer period at an agreed price without capital investment...
