Battery Storage

Our campus is battery powered.

Cobb EMC is using battery storage on campus to further our commitment to innovative sustainability solutions for our members and the community.

Solar panels and other renewable energy resources produce power that can be used immediately, stored or injected back into the grid. Battery storage systems are what enable us to save this energy for later. Why save the energy? Renewable energy production often varies based on weather conditions. By storing renewable energy in a battery, we can save it for a rainy day or any time when renewable energy production is lessened. The battery’s charge can also be deployed when electricity is in high demand and power costs are high, like on a hot summer day. 

Cobb EMC on-campus battery storage

As a part of our commitment to a cleaner energy future, we're proud to be the first utility in the nation to install a battery storage system on our campus to help power operations. Our battery stores the excess power generated by solar on our campus. It also serves as an educational destination for our community.

  • How long does it take to fully charge the battery storage system? The charge time for a battery storage system depends on the rate at which renewable energy is produced, the amount of energy being used immediately upon generation and the size of the battery. If all of the energy produced on our campus goes directly into storage, it will take about 4 to 7 hours for our battery to fully charge.
  • What is the capacity of the battery? We have a 1-megawatt lithium-ion battery that can discharge 4 Mwh of energy. When the battery is fully charged, we can switch to full battery powered operations, allowing us to power all six buildings on campus for up to 8 hours. A battery of this size, when fully charged, could power 200 homes during peak periods for 4 hours.
  • What will we learn from this project? This energy storage project will teach us how to better support the solar and battery needs of many of our large commercial members. Battery storage is also a key component of microgrids, which can make our electrical grid more resilient, if implemented in the future. This battery storage project underscores our goal to meet the energy needs of today and tomorrow, while honoring our commitment to sustainable resources and keeping electric rates low.

Types of battery storage systems

Battery storage systems vary by size, type and need. Battery storage use cases include homes, businesses and utility-scale.

  • Residential battery: Homeowners with rooftop solar can choose to install a battery in their home to help save on energy costs and serve as a backup in the event of a power outage. Popular residential battery manufacturers include Tesla and Sonnen, both of which produce batteries that can store from 10-30 kWh of electricity.
  • Commercial battery: Commercial businesses can benefit from battery storage technology by storing excess solar output. Businesses typically require more power than homes and need a larger battery. A typical commercial battery can store from 30 kWh of electricity up to several megawatts.
  • Utility-scale battery: Utilities can choose to invest in large-scale battery storage in order to boost the resiliency and cost effectiveness of the overall electrical system. Utility scale battery storage involves hundreds up to thousands of megawatt hours of battery capacity that can be charged and discharged to save on power costs.

Battery storage benefits

  • Cost savings: Battery storage systems enable you to save renewable energy for times of day when electricity is in highest demand. These peak times are associated with higher energy costs, so by switching to battery power during these times, you can save money while also operating on renewable energy.
  • Increased reliability: In the event of a power outage, a battery storage system can serve as backup until power has been restored. Battery storage systems have a higher capacity than most generators and are more powerful when it comes to keeping everything in your home or business running while the power is out.
  • Environmentally friendly: By using the renewable energy stored in your battery during peak or evening hours, you are lowering your demand for grid-provided power, and instead optimizing the carbon reduction capabilities of your solar system.

Want to know more about battery storage? Email our energy experts who can help answer your questions.

The warranty on each battery is determined by the manufacturer, however, most batteries have a lifespan of 10 years or longer depending on operations and maintenance.

Battery storage systems store energy for later use. This energy can come from excess power produced by rooftop solar or from the grid. Every battery storage system is equipped with an inverter that allows the energy to be converted from DC to AC, so that it is usable for the home or business.

The amount of time a home or business can run exclusively off battery power is determined by the size of the battery and the extent to which it is charged. A typical home could run on a fully charged battery for about 2-3 hours during an outage.

No, it is not recommended to go completely off grid with a battery storage system and solar array. While your solar array may produce excess power at times, a solar array and battery are often not enough to completely power your home or business year-round due to fluctuations in the weather. The grid provides the reliability you need when your solar array does not produce enough.