On the surface, it makes little sense to put a big battery bank next to a commercial solar array. As it is, solar power is more expensive than the grid in most places, so adding pricey batteries would just push the cost of energy up more.
But what if you could finance the energy storage equipment, much the way solar panels are, and the batteries provided a revenue stream?
In an off-grid solar scenario, old-school lead-acid batteries are just there to provide power at night and cloudy days. But modern grid-scale battery systems are only put in place to save money or provide services to the grid.
The grid energy storage market is benefiting from the big investments the auto and battery industries have made in lithium ion technology and manufacturing. These batteries are more expensive per kilowatt-hour than other types of energy storage, but they are well suited for frequency regulation where fast response is valuable.
For the customer, having four hours of back-up power for critical loads, particularly if the battery can be recharged with solar panels, means a building can stay in business during an outage.