Lux Research recently released a report Batteries Included: Gauging Near-Term Prospect for Solar/Energy Storage Systems that projects that the coupled Solar and energy storage (lithium ion batteries) market will grow to $2.8 billion in 2018. Lux projects that residential applications will be the primary driver through 2018 growing to 382 MW in 2018. It will be followed by the light commercial segment which is projected to reach 220 MW by 2018. Most of the installations (95%) will be linked to the electric power grid.
SolarCity offers a home Lithium-ion battery system and has just announced a commercial energy storage system with smart software (DemandLogic) running behind the meter in selected California, Massachusetts, and Connecticut markets and expects to be able to offer the service across the U.S. by the end of 2014. The battery system uses Tesla Motor's advanced battery technologies.
The home battery system is wall-mounted and about the size of a solar power inverter. A fully charged battery will power basic home needs for a few days and a solar powered home can recharge the battery from the sun to run indefinitely. Basic home needs include charging cell phones, basic lighting, and home security systems.
In the commercial market the battery system is being marketed primarily as a backup system during emergency power outages.
But another benefit is targeted at people and businesses on a time-of-use tariff, because the battery can be used to shift power grid consumption from peak to off-peak. For the same overall power usage, this will reduce the monthy power bill.
Coupled solar and storage
Solar photovoltaic (PV) cells installed on the roof generate direct current (DC) when hit by sunlight. The DC power is converted by an inverted into alternating current (AC) power. The AC power travels goes to a breaker box.which connnects it to your home AC electricity network. Any excess DC power is uses to charge the battery. The home remains connected to the utility grid so you can use grid power when it is available.