Is it possible to power all of your appliances with a solar battery, or should you go with a gas generator instead?
Homeowners everywhere are considering home energy storage as a way to combat the increasing number of power outages occurring throughout the country.
Some areas in Texas have been seeing days-long power outages due to extreme weather, and California’s pre-planned power shut-offs can go on for a full 24 hours. It’s no wonder people are losing their faith in the grid and looking to put it somewhere else.
Even if you don’t have solar panels, a solar battery can be a great way to ensure your most important appliances are up and running when the power goes out. However, it’s probably not the right solution if you’re looking to power your entire house.
So, how can you figure out what appliances a solar battery can power, and more importantly, how long will they stay up and running? We’ll help you find the answers to these questions and more in our in-depth guide.
Key takeaways
- Once you’ve established what your essential loads are, you can figure out how much power you’ll need your battery to release.
- A battery’s output is what determines how many appliances you can run. Most solar batteries come with power output ratings of about 5 kW, which means they can provide enough power to run a refrigerator, clothes dryer, and an electric stovetop at once.
- A battery’s size determines how long your appliances can run. A typical 10 kWh battery can power a fridge for 14 hours, a television for 130 hours, or a single LED light bulb for 1,000 hours.
- Homeowners usually choose to back up essential loads like their fridge, WiFi router, lights, and a few outlets, as opposed to their entire home, to keep the size and cost of their battery system low.
Identifying your essential loads
Before you can even start to consider what battery to get, you’re going to need to sort out what appliances you want to power. These are called your ‘essential loads’.
You can make anything an essential load. Can’t live without watching TV? Make it essential. You need to do laundry when the power’s out? Make the washer an essential load.
Whatever you determine is essential will be put on the backup load panel that gets installed with your battery. It’ll work just like your regular circuit breaker, but it only contains the appliances you have deemed essential to have running during a power outage.
Essential loads are not critical loads! You may come across the phrase ‘critical loads’ when you're looking up solar battery backup, and a lot of people use it interchangeably with ‘essential loads’. However, they are not the same thing. A critical load would be something like medical equipment that absolutely cannot be turned off and needs to be connected to an uninterrupted power source.
Common essential loads
Again, anything can be an essential load if you want it to be, but what you pick will determine what kind of battery you need. Most people do not back up their entire house, and instead pick a few of the most important things they need to make it through an outage, like:
- Refrigerator
- Lights
- WiFi router
- A few outlets
- Television
- Electric stove
- Microwave
These loads ensure your life continues to run smoothly, but don’t require you to install a huge energy storage system. Adding on more powerful appliances, like air conditioners, will likely require more than one battery, which can cost a pretty penny.
Figure out how much power output you need
A battery’s output determines how many (and which) appliances you can run.
Most solar batteries today have a continuous power output of around 5 kilowatts (kW), which is enough power to run a standard refrigerator, clothes dryer, and an electric stovetop at once.
But chances are, those aren’t the same loads you want to be running when the power goes out. For instance, the essential loads you want to run might require less power from your battery.
It’s pretty easy to find out how much power you’ll need your battery to release once you’ve established what your essential loads are. All you have to do is find the wattage requirements of your appliances and add them all up. You can usually find the wattage listed on a label on the back or bottom of the appliance, or in an owner’s manual.
Here’s an example using some of the common essential loads we listed earlier:
| Essential load | Wattage |
|---|---|
| Refrigerator | 700 W |
| Lights* | 400 W |
| Electric stove | 2,500 W |
| Microwave | 900 W |
| Laptop charger | 61 W |
| Phone charger | 20 W |
| Television | 77 W |
| WiFi router | 5 W |
| Total power demand | 4,663 W |
*Assumes 40, 10-watt LED light bulbs
To run all of the above appliances at once, you would need to get a battery with a minimum power output of 4,663 watts (or 4.66 kW), which falls in line with what most solar batteries are capable of.
Watt the heck? It can get confusing when talking about watts and kilowatts. Although most of your appliances will have their power ratings listed in watts (W), most batteries have their power outputs listed in kilowatts (kW). It’s easy to convert watts to kilowatts: simply take the number of watts and divide it by 1,000. That means for our example, you divide 4,663 by 1,000, which gives you 4.66 kW!
Peak power output
Some appliances need a bit of extra power to get up and running. Usually, these loads have motors, like refrigerators and sump pumps, and the amount of power they need to start will be listed somewhere on their label as the ‘startup wattage’.
The good news is, solar batteries have a peak power rating that tells you the maximum amount of power the battery can release in a short period of time, which is usually about 10 seconds. This has been designed specifically for providing extra power to those appliances that need it in order to turn on. Most batteries have a peak power output around 7 kW.
To find the peak power output, you would need to run your essential loads and add the startup wattages of all your appliances that have them to the total continuous power demand of your loads.
Using the example from the above table, let’s say your refrigerator is the only appliance that has a startup wattage. We already have a total power demand of 4,663 watts. If that fridge had a startup wattage of 1,050 watts, we would then add that to the total power demand (4,663 watts) for a peak power demand of 5,713 watts, or 5.7 kW.
Power requirements for bigger loads
Like we said before, adding power-hungry appliances like an air conditioner or washing machine need bigger battery systems in order to run.
In our example, we said we would need about 4.7 kW of power to run those essential loads. If you add a central AC unit onto that, you’d need a battery that can deliver 8.2 kW of power. When you take its startup wattage into account, you’d need a peak power rating of almost 14 kW.
Basically, you’d need a whole separate battery just to run the central air. Because of this, most people choose not to have these larger appliances as one of their essential backup loads, and instead opt for plugging in a fan or two.
How long do you need power for?
A battery’s size determines how long your appliances can run for.
When we talk about battery size, we’re referring to how much electricity the battery can hold, in kilowatt-hours (kWh), for your home to use. This is most commonly called the ‘usable capacity’ of the battery.
Watt's the difference? Though kilowatts and kilowatt-hours sound the same, they’re actually completely different. A kilowatt is a unit of power, while a kilowatt-hour represents how much power is used over a period of time. How much energy is stored in a battery is typically measured in kWh.
Learn more: Watts, kilowatts, and kilowatt-hours explained
Most solar batteries are 10 kWh in size, which can run:
- The average refrigerator for 14 hours
- A television for 130 hours
- An LED light bulb for 1,000 hours
- A WiFi router for 2,000 hours
However, it’s unlikely that you want to back up just one appliance in the event of a power outage. That means if you want to power more appliances, you won’t be able to run your fridge for a full 14 hours, because another load will be using the energy stored in your battery at the same time.
Let’s take a look at our essential loads again for an example of how long a 10 kWh battery could power multiple appliances in your home:
| Essential load | Wattage | Hours | kWh consumed |
|---|---|---|---|
| Refrigerator | 700 W | 8 | 5.6 kWh |
| Lights | 400 W | 5 | 2.0 kWh |
| Electric stove | 2,500 W | 0.5 | 1.25 kWh |
| Microwave | 900 W | 0.25 | 0.23 kWh |
| Laptop charger | 61 W | 2 | 0.12 kWh |
| Phone charger | 20 W | 4 | 0.80 kWh |
| Television | 77 W | 2 | 0.15 kWh |
| WiFi router | 5 W | 8 | 0.4 kWh |
| Total kWh needed | 9.47 kWh |
In this example, a 10 kWh battery would be able to run your most important loads, like the fridge and WiFi router for 8 hours, and still let you use your other appliances before it needs to be recharged.
If you installed a 15 kWh battery, you could potentially run more loads than the ones we listed in this example. Or you could run the same loads for a longer period of time instead.
How top battery manufacturers stack up
There are a ton of different solar batteries on the market, and the one that’s right for you depends on what loads you want to run, how you want to use them, and your budget.
| Battery model | Capacity | Power output | Price* |
|---|---|---|---|
| sonnenCore | 10 kWh | 4.8 kW | $9,500 |
| Tesla Powerwall | 13.5 kWh | 7.0 kW** | $9,200 |
| Generac PWRcell | 15 kWh | 7.5 kW | $17,000 |
| LG Chem Prime | 16 kWh | 7 kW | $9,500 |
*Estimated price before installation and incentives like the federal solar tax credit and SRECs
**The Tesla Powerwall’s output depends on current weather conditions and whether you are operating on or off-grid. This power output assumes the system is operating off-grid with no sun.
Any of these batteries would be able to successfully power the bare minimum of appliances. With that said, some of them are better suited for power outages than others.
The sonnenCore has the smallest capacity and the lowest power output, which means it will power the least amount of appliances for the shortest amount of time. This makes the sonnenCore better in places that experience the occasional one or two-hour blackout.
If you experience prolonged blackouts somewhat regularly, you’re going to want to choose a battery with the highest capacity and the highest power output. The Tesla Powerwall and Generac PWRcell are great options because you can install several of them to power more loads for longer periods of time. Keep in mind, however, the Generac PWRcell comes with a pretty hefty price tag.
The LG Chem Prime offers a great capacity and power output; it can power the most appliances for the longest amount of time on this list - without costing you an arm and a leg. Plus, it works great as an everyday battery and not just during outages, as it can run your home at night when your solar panels aren’t producing any electricity.
You can check out more specs, costs, and other comparisons of a variety of solar batteries in our in-depth guide here.
Is a solar battery better than a generator during an outage?
Solar batteries are a great way to get backup power for homeowners who are okay with only running a few appliances during a grid outage. Technically, you can power your entire home with batteries, it’ll just cost a significant amount of money.
Homeowners looking to backup their entire home are probably going to want to get a gas generator, as it’ll end up being cheaper than whole-home battery storage. But the good thing about batteries is that they don’t just provide value during a power outage. You can use a solar battery every day, even when the grid is up and running.
By using a battery to store your excess solar energy, you can reduce your reliance on the grid, lower your electricity bill, and maximize the amount of clean electricity your home uses. Our solar calculator will give you an idea of how battery storage impacts your solar investment, and how many batteries you’ll need to power your specific home.
Catherine Lane
Written Content Manager
Catherine is the Written Content Manager at SolarReviews. She has been researching and writing about the residential solar industry for four years. Her work has appeared in Solar Today Magazine and Solar Builder Magazine, and has been cited by publications like Forbes and Bloomberg.