Solar panels on AZ house with mountains in the backgroundSolar Battery Sizing Guide: How Big of a Battery Do You Need?

Size is one of the most important factors to consider when investing in a solar battery. The amount of storage capacity your battery has will determine what appliances it can back up and for how long. 

SouthFace Solar & Electric installs custom solar battery banks for grid-tied and off-grid solar energy systems. We wrote this guide to help you understand how solar battery backup works and how many solar batteries you need to get the amount of backup power you want. 

Solar Battery Storage Capacity 

When we talk about solar battery size, we’re referring to its storage capacity. Storage capacity is the amount of electricity a single battery can hold. Storage capacity varies from one battery to another, but most can hold about 10 kWh of electricity. Most solar batteries are also stackable. That means you can combine multiple units to get the amount of backup power you need. 

Whole-Home vs Partial-Home Backup 

So, how big of a battery do you need for your solar system? It depends on how much backup power you want. Solar battery systems can be sized for whole-home or partial-home backup. 

Whole-Home Solar Battery Backup 

A whole-home solar battery system allows you to back up your entire electric service panel. For whole-home backup you’ll need: 

  • A lot of storage capacity (multiple solar batteries)
  • Enough solar panels to recharge your batteries as they drain 

Whole-home solar battery systems have enough capacity to power your entire home, but your loads are still prioritized in order of importance. For example, your refrigerator, Wi-Fi router, and a few outlets may be your essential loads while your dishwasher, washing machine, and clothes dryer are secondary loads. As your battery drains, secondary loads will automatically turn off so your essential loads can stay on. Once your battery recharges, all loads will be back up and running. 

Partial-Home Solar Battery Backup 

Most people choose to back up their essentials with solar battery storage instead of their entire house. Partial-home backup systems separate essential loads like your fridge, Wi-Fi router, and a few outlets from the rest of your service panel and tie them into your battery system. Your battery keeps these loads running while the rest of the power in your home is shut off. Most homes can be partially backed up with one battery (~10kWh).

What About Electric Generators? 

A home generator is another great option for home backup power in Arizona. Like solar batteries, backup generators come in a variety of sizes and can be used for whole-home or partial-home backup. 

Whole-Home Generators 

Whole-home generators provide backup power for your entire home by burning fuel to create electricity. Most whole-home generators can detect a power outage and will turn on automatically when your grid connection is lost. A whole-home generator is a great alternative to solar battery backup if you don’t have or plan to install solar panels. 

Partial-Home Generators  

Portable generators provide backup power for select loads and can be used for partial-home backup. They can be used to keep a few essentials running but are better for RVs, job sites, and other temporary situations. For permanent backup power, we typically recommend whole-home generators over partial-home generators because they provide a much greater value. 

Custom Sizing for Backup Power Systems in Arizona 

Knowing you have a reliable backup power source provides invaluable peace of mind and will keep your family safe and comfortable during a power outage. SouthFace Solar & Electric installs solar batteries and home generators and can help you find and compare the best backup power sources for your home. We custom-size our backup power systems to make sure you have the storage capacity you need to keep your home running for hours or even days at a time.

Find the right backup power source for your home. Call 480-405-6105 or contact us to schedule your free consultation.

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