Solar Battery

What is a Solar Battery?

Formally, a solar battery is defined as a networked grid of photovoltaic cells. Practically, a solar battery refers to a storage device used to store power generated by the sun.

Key Takeaways:

  • Solar batteries have formal and colloquial definitions that refer to different devices.
  • Capacity and power rating are two of the most important metrics to consider with a solar battery
  • Local utility companies may act as the solar battery for certain photovoltaic system owners.

Understanding Solar Batteries

Officially, a solar battery is defined as a networked series of connected solar cells. But colloquially and more practically used, a solar battery is simply a battery that is charged with the power generated by a solar array and meant for consumption during hours that the array is not generating electricity. They can range in size from very small (pocket-sized) to utility scale that is meant to power entire cities.

The biggest benefit to a solar battery is that a consumer will be able to power their home or business during times that the sun is not shining or during peak power demands and power outages. In order for a consumer to determine what solar battery is right for their application, they will need to know two key factors: how much power a solar battery is able to store, and how much power a battery will be able to provide at any given moment.

The solar battery’s capacity will tell a person what the total amount of power it can store is, as measured in kilowatt-hours (kWh); while the battery’s power rating will disclose the maximum amount of power that can be supplied at any one point in time in terms of kilowatts (kW).

To better understand how these two metrics are important, consider the case of two batteries: Battery A which has high capacity and low rating, and Battery B which has a low capacity but a high rating.

Battery A will be able to supply power for a small number of important appliances for a long time.

Battery B will be able to supply power for your entire home, but only for a short period of time.

Also important is a solar battery’s lifespan, or cycle life. This is the total number of charge-discharge cycles that a battery will be able to endure before battery life and performance will start to degrade. Battery life also degrades over time regardless of cycles, so knowing the estimated lifespan for a battery is very important.

For many residential or business photovoltaic system owners, a battery bank will not be required to capture savings because your local utility will act as the battery and provide power during non-daylight hours. That said, the power utility will not be useful when there is a power outage or during extreme weather events. In those situations, or for photovoltaic array owners who want to be more self-sufficient, a robust battery system will be a critical component of the system.

Related Terms

Battery – A storage device for electrical energy, typically in a chemical solution, that can be used as a source of power.

Battery life – The length of time a device can continue to work before it needs its battery to be recharged. 

Photovoltaic System – A photovoltaic system refers to the entire system of photovoltaic devices and supporting equipment required to generate electricity from light. A complete system may include some or all of the following: a photovoltaic array, an inverter, mounting, cabling, a solar tracker, and a battery.