Solar Battery vs. Generator: Which One Is Right for You?

Jul. 22, 2020

New England homeowners are no strangers to power outages that can cause blackouts for a few hours or up to a few days. Traditionally, homeowners looked to portable or whole-home standby generators to keep their essential appliances running when a Nor’Easter hits. However, in recent years, there has been an increase in interest in using a solar PV (photovoltaic) system with solar battery storage. 

In 2020, while there is a lot going on that we can’t control, we can control how we get our energy and how we can store it for our homes. So, solar battery vs. generator, which one of these backup energy systems is best for you, and how do they work?


Solar Battery Backup

Solar battery systems store excess energy from a power source like your solar panels or the electricity grid, and save it for later use.

When you combine energy storage from a solar battery, like Tesla Powerwall or sonnenBatterie, with your solar PV system, the battery will save any of the excess energy generated by your solar panels for use during times of low solar output, like at night. Tesla Powerwall stores 14 kWh of energy while sonnenBatterie has products that range from 5 to 20 kWh capacity, depending on your home’s energy needs. Tesla Powerwall comes with a 25 year performance guarantee. 

During a power outage, a grid-tied solar PV system will be shut off and you will be left without power just like your neighbors who are hooked up directly to the grid as well. When combining solar panels with a solar battery, your system will disconnect from the grid but your battery will start powering your home without any interruption.  You can also size your battery backup system to power your essential energy loads or your whole-home.  

Examples of the times you might use a solar battery backup are:

  • At night or low solar output

  • During an outage

  • Times of high electricity rates (in the case of time-of-use programs)



  • No added noise/quiet operation

  • Operates on renewable energy when combined with solar

  • Increases your daily solar consumption 24/7

  • Qualifies for MA state and federal tax credit incentives

  • Extremely low maintenance

  • Seamless operation during an outage



  • Higher price tag

  • Limited power capacity (if grid connected)

Powered Backup Generators

Portable or standby generators are the backup power technology most homeowners are already familiar with. Backup generators create their own electricity by burning fossil fuels like propane, natural gas, or even diesel. They are installed outside the home, and can include sensors to detect an outage when it occurs for automatic operation. Backup generators are more affordable to purchase, but they do come with some small monthly costs since they often require weekly self-tests, on top of any fuel you use while they’re running during an outage. A well-maintained standby generator will tend to last 10,000 to 30,000 hours in its lifespan (or if run consecutively that’s up to 3.5 years). 


Backup Generator Pros:

Less expensive than solar batteries

Can be connected to an existing natural gas line

Can provide power 24/7, given a steady fuel supply

Flexible options from a small portable to whole-home standby 


Backup Generator Cons:

Noisy operation

Higher carbon footprint

Requires maintenance 

Monthly fuel costs


Choosing the Right Backup Power

So, which option is going to be best for your home? Here are our recommendations. 


If You Are:

  • Only looking for emergency power

  • Not planning to install solar panels in the future

  • In a home with an existing natural gas line


...Then a standby backup generator may be the best option for your home.


If You Are:

  • Wanting to combine backup power with a solar energy system

  • Looking to power your home 24/7 and in an outage all from renewable energy

  • Looking to reduce peak electricity charging


...Then a solar backup battery may be the best option for your home.

If you are looking to make the right choice for your home when it comes to backup power, Boston Solar is here to answer your questions, like how long a Tesla Powerwall or sonnenBatterie last, what a Tesla or sonnen battery costs, or any other questions you might also have about solar power. Get an idea of what solar battery backup would look like with a free solar quote today!

Looking to keep the lights on during an outage? Choose the right backup power solution with Boston Solar. Call 617-858-1645 or get in touch for a free quote.

Solar Battery vs. Generator: Which One Is Right for You?

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