Solar Battery Backup vs Generators

It is very common for customers beginning to research solar to type solar generator into the search box. Nine times out of ten, what they really mean to search is solar with battery backup. So, what is the difference between a battery backup system and a generator? Read on to find out!


First let’s break down the definitions of a generator and battery backup.

Generator: Converts mechanical energy to electrical energy. Most commonly seen as a gas, propane or diesel engine that spins a metal conductor in a magnetic field to cause electrons to flow in that is then used as electricity.

Battery Backup: Converts chemical energy to electrical energy. Most commonly seen as lithium ion nowadays. Still available are lead acid, AGM (another type of lead acid) and other battery chemistries including some that use salt water. These battery systems all consist of a specific chemical solution between positive and negative plates in what are called cells. These cells charge and discharge with Direct current, or DC electricity. This electricity is typically inverted to create AC electricity which is used in most all residential and commercial applications.

The Venn Diagram below gives you a good idea of the differences between battery backup and generators which we will go more in depth below.

venn diagram template

Solar Battery Backup

As mentioned previously, when customers begin their research for backup power and type in solar generators, what they are likely looking for is a solar system to provide power when the grid is down. This is called a solar with battery backup system.

Solar with battery backup systems store electricity produced by the sun. These systems provide a reliable way to generate electricity, store it, and use it later both when the grid is up or down, with no interruptions and no downtime. Battery backup systems are quiet, get installed inside, can take up less space, and are more environmentally friendly than their generator counterparts. They rely on renewable solar energy produced from the sun to perpetually recharge the batteries, never having to worry about running out of fuel. They work without emitting any harmful greenhouse gasses once installed on site. These systems require little to no maintenance at all for the lifetime of the system. 

Solar with battery backup systems are versatile and serve many purposes. For one, they can be used both when the grid is on or off. When the grid is on, and the system is in backup only mode, electricity from the solar panels will keep the batteries 100% charged, then power the loads on the in the house, then any additional electricity from the solar panels will be sent back to the grid for credits. In North Carolina this is called net metering. Learn more about Net Metering in our other blog post HERE. In this battery backup mode scenario, when the grid goes down, the home or business will seamlessly have power from the batteries and the building’s critical loads will be run off the batteries & solar. 

The other way these solar with battery backup systems can be used is from time-of-use or self consumption. In some scenarios you may want to operate the system while being connected to the grid but not pulling any power from the grid. You can program to cycle your batteries so they power the loads in your home during the night when the solar is off, or during specific times of the day when the utility company in your area may be charging higher rates for electricity to lessen demand on the grid. This is called time-of-use and is growing to be a more common way for utility companies to charge for power. 

Solar with battery backup systems can be pricier upfront but can still provide favorable return on investments due to the tax credit savings and the lower to non existent utility bills. As mentioned above, the solar power will power the loads in your home and sell excess power back to the utility for credits. These credits are used to lower your utility bill throughout the year. There are additional financial benefits worth mentioning is the additional equity in your home and your home being more likely to sell faster due to having solar. To learn more about tax credits, and home equity with solar,  please visit our FAQ page HERE and blog post HERE . 

The downsides to solar with battery backup systems are the higher upfront costs as well as the limited capacity that a battery may provide. Most battery systems available in 2022 are able to power most of the loads in your home, but struggle with the large loads that generate heat. Typical battery backup systems provide 20-65 amps of backup power with some able to do upwards of 200 amps. Cost can get out of hand quickly so most owners end up with a solar and battery backup system that covers their critical loads. These are typically all of the lights, outlets, fridge, well pump, small appliances, microwaves etc. The loads that typically get left out are the heat pumps, HVAC equipment, water heaters, ranges/ovens, dryers etc. During the design process of your solar with battery backup system, Rhino Renewables look at the loads you need backed up when the grid is down, your budget, and your solar access to determine the size solar and battery backup system that fits your needs. 

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The term “solar generator” is a misnomer. Technically a solar generator does not exist.A generator runs on fuel such as liquid propane, natural gas, or diesel. Depending on the generator, they can either automatically turn on when the grid is down or may have to manually be plugged in and started. Generators can take up a good amount of space outside due to the air flow that is required around them to dissipate the heat created from the engine running. They can be very loud, and emit a lot of fumes when running. Generators require constant maintenance both when the generator is being used or stored.

That all said, the one undeniable benefit of a generator is the amount of power you get for the cost. Most generators are able to put out a lot more amperage and provide the instantaneous power required for heavy loads like heat pumps or electric stoves. Generators can be affordable initially when compared to battery backups, though the maintenance and fueling costs add up over time. To add to high maintenance costs, generators are incapable of selling power back to the grid so there is never the potential for any return on investment. Though generators have a lower sticker price, they are ineligible for any of the renewables energy subsidies available through tax credits, rebates, grants and other monies available for renewable energy and solar systems.

For those concerned about their carbon footprint, generators are the least appealing option because of the emissions they create that cause harm to the environment and the amount of nonrenewable fuel it uses. A typical generator is expected to last 10+ years.

Are there systems that incorporate solar, batteries and generators? Yes! There are two more systems that function for back up power that incorporate these power sources.

First is a multi use system that has solar, batteries and a generator. A system of this nature is your most redundant option to having backup power. Here, you are able to run the selected loads from the batteries. During sunny times of the day, the batteries will recharge from solar and other loads may be able to receive power from additional solar being produced. In times that the solar power is not enough to recharge the batteries during a grid outage, say it’s night time or there is snow covering the panels, then a generator is used to recharge the batteries and continue powering the home or business. The systems rely heavily on the controller and depending on the system type, will work seamlessly and automatically based on the parameters programmed into the controller.

Second, is a grid tied solar system with a backup generator. This is a very economical option to take advantage of the financial and environmental savings from solar, will still have back up power and avoid the upfront cost of purchasing batteries. In this scenario, solar power is produced when the grid is on to power the home and be sold back to the grid. When the grid goes down, the solar panels automatically turn off and a fossil fuel generator is then used to power all or some of the loads in the house. This can be a great option if you already have a generator and are looking to add solar onto your home or business.

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Rhino Renewables is happy to help answer any further questions you may have on any of the above system options. Please give us a call at (828) 417-7060 or click the button below!

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