As energy storage solutions increase in popularity thanks to the marketing prowess of large manufacturers, many of our solar customers express interest in battery system additions to their solar arrays. Battery storage systems have myriad uses and benefits both for on site users and the electric grid as a whole. But for homeowners, their main value proposition can be boiled down to three key benefits.
Time of use bill and demand charge management
During peak electricity consumption hours, utilities often charge higher rates referred to as time of use (TOU) rates. Storage can be used to reduce the impact of TOU rates by charging batteries during off-peak or mid-peak hours when rates are lower (or from the free power of the sun!), and discharging during high-peak, thus avoiding higher rates. Less common for residential customers, some utilities include extra demand charges based on the highest usage recorded during short intervals (typically 10-20 minutes) in any given month. Any customer that uses a large amount of power over short periods of time is subject to higher demand charges. Energy storage can reduce this by discharging batteries during those intervals of intensive energy consumption.
Increased self consumption of solar electricity
Sometimes a utility’s rate structure is not favorable to distributed solar, such as a lack of or under valued compensation for exporting electricity generated but not used by behind the meter solar (i.e. no net metering). In this scenario, the ability to store excess generation allows the system owner to retain the value of that electricity.
Back up power
Of course, in the event of a grid outage, a battery backup solar energy system can provide off grid electricity to run any specific set of loads.