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tesla powerwall solar battery vs home generator

Solar Battery vs Generator: Which Is Best for Emergency Power Backup?

When the lights flicker and the power goes out, every minute can feel like an hour. From the unsettling quiet of a dark house to the more serious risk of losing access to phones and medical equipment, power outages threaten your comfort and your safety. 

In these critical moments, having a reliable source of emergency power makes all the difference. 

There are a few options for home backup power, but the debate typically comes down to two main contenders: a standby generator or a solar battery. In this guide, we explain the pros and cons of solar batteries vs generators to help you decide which option is the best emergency backup power for your home.

Solar Battery Backup: What It Is & How It Works

A solar battery is an energy storage device that can be integrated into a solar panel system. They work by storing electricity produced by your solar panels. The stored energy can then be used to power your home during a grid outage. Keep in mind that solar panels do not work during a power outage unless you have a battery. Grid-tied solar panels are automatically shut down during a power outage as a safety precaution, but solar plus battery systems can temporarily disconnect from the grid and remain operational.

Standalone Batteries Work Without Solar Panels

Battery storage systems like the Tesla Powerwall 3 are typically integrated into solar panel systems, but they can also be installed without solar. These systems are referred to as standalone batteries. If you install a standalone battery, it will charge from the main electric grid, creating a bank of stored power you can use when the grid is down. Without solar panels, however, your battery won’t be able to recharge during a grid outage.

Pros & Cons of Solar Battery Storage

Solar battery backup systems have many advantages over propane generators, especially when installed as part of a solar panel system, but they also have some drawbacks.


  • Environmentally Friendly – Solar batteries store renewable energy generated by solar panels, unlike backup generators which burn fossil fuel. 
  • Silent Operation – Unlike backup generators which can be noisy, solar batteries operate silently and with no exhaust fumes. 
  • Low Operational Costs – Solar batteries recharge from your solar panels (when installed as part of a solar energy system) which means there are no refueling costs. They also don’t require regular maintenance, and are easy to control and track battery health using your phone.
  • Long Term Outages – Because they recharge from the sun and don’t rely on fuel delivery, solar batteries have the potential to provide backup power for weeks or even months during the long term outages that can occur after major disasters such as earthquakes.
  • Incentives – With the federal solar tax credit, you can save 30% on your solar battery installation costs. Your battery will also be exempt from Washington State sales tax if it’s installed as part of a solar panel system.
  • Size and Location – batteries are typically smaller than generators, and also can be installed either inside or outside.  This gives you more flexibility on where you want to put your battery compared to a generator. 


  • Weather Dependent – You need sunlight to recharge your battery with solar power, which can limit the total run time in the winter or during a storm.
  • Initial Cost – The cost of a solar panel and battery system is high compared to a standby generator, but there are incentives available to make your installation more affordable.

Backup Generators: What They Are & How They Work

A backup or standby generator is a device that kicks in automatically to provide backup power during a grid outage. They’re powered by a fuel source like propane, natural gas, or diesel. Since there is limited natural gas distribution on the Olympic and Kitsap Peninsulas, most generators in our area are powered by propane. 

Pros & Cons of Backup Generators

Backup generators have several benefits, but like solar batteries, they also have their drawbacks.


  • Cost-Effective Energy Storage – Propane and diesel tanks can store large amounts of energy much more cost-effectively than batteries. This makes them more suitable for handling heating loads during long outages in the winter.
  • Power Large Loads – Standby generators can typically handle large loads like a heat pump or air conditioner. Advanced solar batteries like the Tesla Powerwall 3 can also start and run large loads, but doing so will drain the battery quickly.


  • Environmental Impact – Propane is cleaner than other fuel sources like gas and diesel, but propane generators still emit greenhouse gasses and harmful exhaust. 
  • Noise – Generators are loud and could be irritating for both you and your neighbors. 
  • Refueling – Generators must be refueled continuously to supply backup power. Refueling costs can add up, and if you run out during an emergency, you may not be able to refuel your generator. Also the larger the propane tank, the pricier the installation.
  • Maintenance – Like anything with an internal combustion engine, generators require regular maintenance.
  • No Incentives – Unlike solar batteries, generators do not qualify for incentives, so you will have to pay for your installation in full.

Choosing the Best Home Emergency Power Backup System

So, which is better: a solar backup battery or a generator? The decision is ultimately quite personal. 

Generators excel at providing large amounts of power for long-term outages and are a good option for households that use a lot of electricity. However, solar batteries are a cleaner and quieter option that costs less to operate. 

As the solar division of Frederickson Electric, Cascadia Solar is uniquely qualified to help you choose the best emergency power backup for your home. We install solar batteries and backup generators for homes and buildings on the Olympic and Kitsap Peninsulas and can recommend the right fit based on your needs and priorities.

Be prepared the next time the power goes out! Call 360-531-6163 or contact us to learn more about your backup power options.