Editing Distributed generation (section)

==== PV storage ====
: Common [[rechargeable battery]] technologies used in today's PV systems include, the [[valve regulated lead-acid battery]] ([[lead–acid battery]]), [[nickel–cadmium battery|nickel–cadmium]] and [[lithium-ion batteries]]. Compared to the other types, lead-acid batteries have a shorter lifetime and lower energy density. However, due to their high reliability, low [[self-discharge]] (4–6% per year) as well as low investment and maintenance costs, they are currently the predominant technology used in small-scale, residential PV systems, as lithium-ion batteries are still being developed and about 3.5 times as expensive as lead-acid batteries. Furthermore, as storage devices for PV systems are stationary, the lower energy and power density and therefore higher weight of lead-acid batteries are not as critical as for [[electric vehicle]]s.<ref name=ethz-harvard>{{cite web |publisher=ETH Zürich, Harvard University |url=https://www.researchgate.net/publication/264239770 |title=The Economic Viability of Battery Storage for Residential Solar Photovoltaic Systems – A Review and a Simulation Model |author1=Joern Hoppmann |author2=Jonas Volland |author3=Tobias S. Schmidt |author4=Volker H. Hoffmann |date=July 2014 }}</ref>{{rp|4,9}}

: However, lithium-ion batteries, such as the [[Tesla Powerwall]], have the potential to replace lead-acid batteries in the near future, as they are being intensively developed and lower prices are expected due to economies of scale provided by large production facilities such as the [[Gigafactory 1]]. In addition, the Li-ion batteries of plug-in [[electric car]]s may serve as future storage devices, since most vehicles are parked an average of 95 percent of the time, their batteries could be used to let electricity flow from the car to the power lines and back. Other rechargeable batteries that are considered for distributed PV systems include, [[Sodium–sulfur battery|sodium–sulfur]] and [[Vanadium redox battery|vanadium redox]] batteries, two prominent types of a [[Molten salt battery|molten salt]] and a [[Flow battery|flow]] battery, respectively.<ref name=ethz-harvard />{{rp|4}}