Why get a home battery
Last updated 8/25/2021
Energy storage is increasing in popularity throughout the US, with installations in homes and businesses more than doubling every year. To date, most of these installations have had one goal in mind (at least at the residential level): emergency backup power. However, backup power isn’t the only reason people invest in energy storage, either on its own or adding it to a solar panel system. There are three main reasons to get a battery, depending on your specific situation: emergency backup power, financial savings, and maximizing self-supply of solar.
Why get a battery: emergency backup power
If you live somewhere that experiences regular power outages, storage is a great option for you. Whether you live in California and experience wildfire-caused blackouts or utility-caused public safety power shutoff (PSPS) events or in the Southeast and experience regular, days-long outages from major-storm events, installing solar plus storage is an ideal way to keep your lights on even during an outage.
When you install a solar-plus-storage system, you’ll be able to keep your home or business running even when the grid goes down. You can power your home with the sun and charge your battery with any excess electricity. When the sun goes down, or if it’s cloudy, you can pull from your battery. So long as the sun keeps shining, you can repeat the process indefinitely.
It’s worth noting, though, that most energy storage systems do not offer whole home backup - in other words, you may need to choose only certain appliances to backup, as opposed to being able to run everything the way you typically would.
Why get a battery: financial savings
There are two primary instances in which energy storage can help you to save money on your electricity bills: if you are on a time-of-use rate or if you have demand charges (as many businesses now do).
Saving with storage on time of use rates
Time-of-use, or TOU, rates are a form of “time-varying-rates”: the cost of electricity varies based on the time of day when you are using it. While TOU rates have been common for businesses throughout the country for many years, it’s a newer way to pay for electricity for homeowners, with homes throughout California transitioning to (or already on!) TOU rates.
Most TOU rates make electricity more expensive later in the day, as or after the sun goes down. But with solar and storage together, you can use the energy stored in your battery instead of pulling from the grid when electricity is at its most expensive during the day.
Saving with storage on demand charges
A number of businesses now find themselves placed on demand charges: the utility will track your maximum energy pull during any given hour (or even fifteen minute period) per month, and will charge you based on that maximum demand for the whole month. In other words, even if you only need 50 kilowatts of electricity during 99% of hours each month, if your usage spikes to 100 kilowatts during even one hour, that’s what you’ll be charged based on at the end of the month, meaning you can see a significant cost for even a small time period of extra demand.
Storage can help mitigate the impact of these spikes in electricity usage, as you can pull from your battery instead of from the grid at peak times. As a result, for businesses on an electricity rate with a demand charge, batteries can help drive significant financial savings.
Why get a battery: use more of the solar you produce on-site
If you live somewhere with a one-to-one net metering policy (i.e., each unit of energy you send to the grid is credited at the exact same cost as each unit of energy you purchase back from the grid), then there’s really no need to maximize the amount of solar you consume at your home or business. One-to-one net metering allows you to use the entire electricity grid as a giant battery at no cost to you!
But there are two reasons you might want to maximize the amount of your solar production you use on-site: 1) if there’s no net metering policy where you live, or, less commonly, 2) if you want to go fully off-grid with solar and storage.
Solar-plus-storage without one-to-one net metering
If your region or utility doesn’t offer one-to-one net metering, adding storage to your solar panel system will help solar make more financial sense. Instead of sending excess solar production from your panels to the grid when you’re not using it, you can use that energy to charge your battery. Then, instead of pulling electricity from the grid when the sun goes down, you can first pull straight from your battery. That way, you’re maximizing the amount of the solar energy that you use at your home or business.
Going off-grid with solar-plus-storage
In most cases, when someone’s interested in going “off-grid” with solar, really what they’re looking for is resilience: the ability to operate and keep the lights on without the grid in the event of an outage. Going fully off-grid is typically not financially feasible–you need to overbuild both the solar and storage to ensure you have power under all circumstances.
However, in a select few instances, going fully off-grid with solar and storage may make sense. In those instances, the role of storage is to allow you to store excess solar production during the day to use at a later point in time when the sun isn’t shining, again maximizing the amount of solar production that you are able to use.
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