Losses on the big high-voltage wires average about 2% in the US. Losses on lower-voltage distribution wires average 4% on top of that - so about 6% in total. [1

Losses on the big high-voltage wires average about 2% in the US. Losses on lower-voltage distribution wires average 4% on top of that - so about 6% in total. [1] Lithium Ion batteries charge near 100% efficiency. [2] In terms of storage (specifically self-discharge), Lithium Ion batteries lose 5% in 24 hours, then 1-2% per month thereafter - but can be as low as 0.35% per month. [3, 4] [1] http://insideenergy.org/2015/11/06/lost-in-transmission-how-much-electricity-disappears-between-a-power-plant-and-your-plug/ http://insideenergy.org/2015/11/06/lost-in-transmission-how-... [2] https://www.powertechsystems.eu/home/tech-corner/lithium-ion-battery-advantages/ https://www.powertechsystems.eu/home/tech-corner/lithium-ion... [3] https://batteryuniversity.com/article/bu-802b-what-does-elevated-self-discharge-do%C2%A0 https://batteryuniversity.com/article/bu-802b-what-does-elev... [4] https://en.wikipedia.org/wiki/Lithium-ion_battery https://en.wikipedia.org/wiki/Lithium-ion_battery