Lucas123 writes: Lithium-ion (Li-on) and flow battery prices are expected to drop by as much as 60% by 2020, making them far more affordable for storing power from distributed renewable energy systems, such as wind and solar, according to a recent report by Australia's Renewable Energy Agency (ARENA). The 130-page report (PDF) shows that Li-on batteries will drop from $550 per kilowatt hour (kWh) in 2014 to $200 per kWh by 2020; and flow battery prices will drop from $680 per kWh to $350 per kWh during the same time. Flow batteries and Li-ion batteries work well with intermittent energy sources such as solar panels and wind turbines because of their ability to be idle for long periods without losing a charge. Both battery technologies offer unique advantages in that they can easily be scaled to suit many applications and have high cycle efficiency, the ARENA report noted. Li-ion batteries more easily suit consumer market. Flow batteries, which are less adaptable for consumer use because they're typically too large, scale more easily because all that's needed to grow storage capacity is more electrolyte liquid; the hardware remains the same.