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Battery Education

From Size to Science: Mastering the Art of Home Batteries


Not all Home Batteries are Created Equal

Size Matters

Battery size, measured in kilowatt-hours (kWh), is crucial because it determines how much energy your home battery can store and for how long it can power your home during outages or peak times.

Real-World Application: Choosing the right battery size depends on your household's energy consumption, the energy demands of your appliances, and your backup energy goals (e.g., full vs. partial home power).

  • Small Batteries (1-5 kWh): Suitable for smaller homes or those with lower energy needs. These can handle essential loads like lights and small appliances.

  • Medium Batteries (6-15 kWh): Ideal for average-sized homes, capable of running the household comfortably but may not cover heavy appliances for more than very short periods.

  • Large Batteries (15+ kWh): Best for large homes or high energy usage, capable of running the entire home, including heavy appliances like air conditioners, for several hours.


Importance of Charge and Discharge Rates

The charge and discharge rates, measured in kilowatts (kW), affect how quickly a battery can be charged or depleted. High rates can handle more instantaneous power needs.

  • Charge Rate: Determines how quickly the battery can convert AC power from the grid or DC power from solar panels to stored energy.

  • Discharge Rate: Indicates how fast the battery can deliver power to your home.


  • Faster rates are crucial during sudden power needs or emergencies.

  • They determine the efficiency and performance of your energy management during peak and off-peak times.

State of Charge (SoC)

SoC is a percentage that shows how much charge your battery has left compared to its total capacity.


  • Essential for managing battery health and understanding when to charge or discharge.

  • Helps prevent overcharging and deep discharging, which can affect battery lifespan.


Depth of Discharge (DoD)

DoD refers to how much of the battery’s capacity has been used.


  • Directly impacts the battery's operational lifespan. Regularly using a high DoD can shorten a battery's overall life.

  • Important to understand for maintaining optimal battery health and efficiency.

Batteries with a high allowable DoD can offer more usable energy per cycle, enhancing the system's utility and often reducing the cost per cycle.

Pro's and Con's of Different Backup Power Options


Natural Gas Backup Generator

Cost:  $12,500 installed


  • Always ready when you need it

  • Can run the entire home.  No need to pick and choose appliances


  • Sunk cost with no monthly payback

  • Higher cost per kWh produced

Cost per kWh produced:    $0.154 cents 

Batteries tied to Grid 

Cost:  $15,000 - $21,000 installed


  • Stable charging from the grid

  • Charge when rates are lowest and use when rates are highest

  • Savings every month for highest ROI

  • Rebates available from Federal Govt


  • Finite power if grid down long-term.

Cost per kWh produced:    $0.025 cents 

Batteries tied to Solar System 

Cost:  $45,000 - $70,000 installed


  • Can produce and charge when grid is down

  • Rebates available from Federal Govt.


  • Heavy up-front cost.

  • Limited home energy use due to smaller battery and inverter setup

  • Ever-changing weather creates unstable solar production

Cost per kWh produced:    $0.102 cents 

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