An Introduction to Solar Battery Storage

Solar Battery Storage 101

Throughout the day, your solar system is constantly converting the sun’s rays into energy to power your home. What happens when your solar system produces more energy than your home needs?

Traditionally, that extra energy is transported back into the grid through net metering, which offsets your energy consumption costs. However, with rapidly changing policy challenging the continuity of net metering and the rising costs of grid electricity, more homeowners are adding a solar storage battery to their solar panels.

A solar storage battery does exactly what its name suggests – it captures excess energy from your solar panels for later use. You’ll be able to draw energy from your solar storage battery at night, on cloudy low-production days, and during grid outages. The technology producing solar storage batteries is rapidly evolving. Below is a quick overview of some of the advantages:

How Long Will a Typical Solar Storage Battery Keep Your Home Running?

During a grid outage, if you have a fully-charged solar storage battery, you can1:
  • Refrigerate food for 116 hours.
  • Burn a 60W light bulb for 155 hours.
  • Run your window AC unit for 5 hours.
  • Run a pedestal fan for 310 hours.
  • Keep your basement dry with a Sump Pump for 8 hours.
  • Charge your phone for 40,734 hours.
  • Operate your WIFI router and computer for 93 hours.
  • Watch TV for 78 hours.
Solar storage batteries also reduce your day-to-day dependence on the grid. When the sun goes down, you’ll be able to power your home from your battery instead of using expensive grid electricity. Backup battery storage is a good addition to any solar panel system - the battery can provide energy where and when you need it most, which means that you’ll use excess solar energy efficiently. Plus, your battery is a reliable backup when the power goes out that keeps your food fresh, allows your garage door to open, and keep your phones charged.

Two Main Types of Solar Batteries:

  1. Lead Acid
  2. Dating back to the 1850’s, lead acid is type of battery you’ll find in your car, golf carts, wheelchairs, and more. Lead acid batteries are cost-effective and dependable. However, lead acid batteries are slow to recharge, and each discharge/charge cycle causes the battery to permanently lose a small amount of capacity.
  3. Lithium-Ion
  4. Lithium-Ion batteries are generally considered to be the most efficient option on the market with very low maintenance. These batteries have an impressive lifespan and tend to be lighter and smaller than lead acid options. Right now, Sunnova offers lithium-ion batteries like Generac PWRcell™ and Tesla Powerwall.

Which Battery is Best for You?

When choosing a solar storage battery, If you want to add a storage battery to your solar system, then it’s key to find out your battery’s capacity to power key appliances until the sun comes out and your solar system produces more energy, or grid power returns. Based on your energy needs, your solar system installer can provide guidance on how your battery will work best for you. For most homeowners, cost is the top driving force behind their decision in solar storage installation. However, when choosing adding a solar battery for your home and your family’s needs, you’ll want to consider the warranty, number of cycles, brand, total capacity and power rating. Let’s dive deeper into these important factors:
  • Warranty. Solar storage battery manufacturers guarantee their batteries over the course of their warranty, usually 10 years or longer. If you’re a Sunnova customer, your battery is also covered by our Sunnova Protect warranty.
  • Cycle Life. All batteries degrade over time. Think about your cell phone battery – the lithium-ion battery in your phone loses charge capacity (the amount of charge a battery can hold) with every charge and drain cycle. A solar storage battery is no different.
  • Cycle life is part of the manufacturer’s warranty - it describes the number of times a solar storage battery can be fully charged and discharged before the charge capacity is greatly diminished.
  • Brand: Different solar storage batteries will have different pros and cons. While it may be tempting to pick a solar storage battery because of its brand name, it’s important find a battery (and a warranty) that matches your energy needs.
  • Depth of Discharge, sometimes shown as DoD, refers to the amount of charge that can be used of a battery’s total capacity before needing to be recharged. If you were to use all 100 percent of your battery’s charge, it would require more maintenance and would cause a higher rate of deterioration, requiring earlier replacement. That’s why most batteries will specify a DoD, which will tell you how much of the battery’s charge can be safely used before needing to switch to grid power and allow the battery to recharge.
  • Power ratings. Take DoD, capacity, and roundtrip efficiency into account, among other factors, and are used to tell you how much electricity the battery can deliver all at once. In simple terms, it’s the difference between powering a few appliances at once versus your entire home at full power. The higher the power rating, the more energy the battery can deliver, however if it’s got a relatively low capacity, it might only provide energy for a short amount of time before your home needs to switch over to grid power.

You Can Bank on Sunnova SunSafe® - Solar + Battery Storage

With Sunnova SunSafe™, as opposed to solar-only systems, solar + storage technology will produce and store energy—even when the grid is down—allowing you to keep your lights on day and night. In addition, Sunnova SunSafe™ offers:
  • Rely on Your Rate - With Sunnova SunSafe™, homeowners are guaranteed up to 25 years of rate protection.
  • Top Technology - You also enjoy intelligent control technology that will automatically detect when to switch from solar energy to stored energy.
  • Stay Protected - Homeowners who choose Sunnova SunSafe™ are always protected with Sunnova’s top-rated up to 25-year warranty. Your solar system is monitored day and night to ensure peak performance – if your solar system needs maintenance or repairs, you’re covered. Plus, Sunnova guarantees the battery performance of our SunSafe™ systems for up to 25 years, the longest warranty in the industry.

Smart Energy for Your Whole Home

Whether you’re looking into installing solar for the first time or have been searching for a way to increase your solar system’s return on investment, solar + storage may be the solution for you. You don’t need to be a scientist to understand the battery option on the market - a basic understanding will help you to feel more confident about the decision you make for your home and your family.

Solar storage batteries are becoming an increasingly popular way for homeowners to decrease their reliance on the grid, increase energy efficiency and save more money. No matter which type of battery you’re considering, taking time to dig a little deeper into the details is the best place to start.



1. The amount of power available from the battery during a power outage is limited, depending on the loads connected, customer usage and battery configuration (i.e. batteries in certain areas may be set up to provide you with the best economic benefit, which may affect the amount of back-up power available). Solar systems and/or batteries may require repairs after weather events and such repairs may be delayed due to forces outside of our control. No assurances can be given that the solar system or the battery will always work. You should never rely upon either of these to power life support or other medical devices.