As solar energy becomes more popular across the United States, many homeowners are asking an important question: How much battery storage do I need for solar power? The answer depends on your energy usage, goals, and location. Whether you want backup power during outages or wish to reduce reliance on the grid, understanding battery storage is key to getting the most from your solar system.
This guide has simplified this topic in easy terms to enable you to make an informed decision.
What Is Solar Battery Storage?
Solar battery storage will enable you to save up the surplus electricity that is generated by your solar panels, rather than selling it to the grid.
This energy can be stored and be utilized:
- At night
- During power outages
- At the times of high electricity rate periods
Popular solar batteries in the U.S., such as the Tesla Powerwall or LG Energy Solution, are designed to work seamlessly with residential solar systems.
Why Do You Need a Solar Battery?
Not every solar homeowner needs battery storage, but it can be very beneficial if:
- You also have frequent power outages
- You desire power autonomy
- Electricity rates are high during peak-time in your utility company
- You would like to maximize self-consumption of solar energy
Battery storage also acts as a security measure against grid instability due to extreme weather.
Key Factors That Determine How Much Battery Storage You Need
Your Daily Electricity Usage
The most significant determination is your daily household consumption of electricity.
The average home in the U.S. has an average of 30 kilowatt-hours (kWh) per day of consumption; however, this is dependent on:
- Home size
- Number of occupants
- Appliances and HVAC systems
- Electric vehicles
Your daily usage is available on your electric bill.
What You Want the Battery to Power
Ask yourself: What do I want my battery to run?
The two popular methods are:
Essential Loads Only
This includes:
- Refrigerator
- Lights
- Internet and phone charging
- Medical equipment
Battery storage in the form of 5-10 kWh is usually adequate when it comes to critical loads.
Whole-Home Backup
This covers:
- Air conditioning or heating
- Washer and dryer
- Kitchen appliances
Depending on use, whole-home backup can be as little as 20-40 kWh or more.
Length of Backup Power Needed
How long do you want your battery to last during an outage?
Short outages (4-8 hours): A smaller battery capacity might suffice.
One day: Calculate at least one day of average use.
Several days: You can require several batteries or less consumption.
U.S. homeowners are typically ambitious in having 1-2 days of backup power.
Solar Panel System Size
Your solar panels should have the capacity to recharge the battery.
For example:
- A solar system can produce a typical output of 25-35 kWh per day with a 7-kW solar system.
- Big systems can accommodate more battery storage.
If you have a small solar system, then a huge battery might not be a viable option.
Grid Connection and Net Metering
In most states of the U.S., net metering will enable you to sell surplus energy to the grid to get credits. If net metering is generous, then you might have to use less battery storage.
However, in states with time-of-use (TOU) rates or less net metering advantages, battery storage is more useful in terms of saving money.
How to Calculate Your Battery Storage Needs (Simple Method)
The following is a quick step-by-step procedure:
- Measure your daily electricity consumption (kWh)
- Choose the percentage that you wish to have backed (50%, 75%, or 100%)
- Multiply your percentage of daily usage
- Adapt the number of hours or days of backup that you desire
Example:
Daily usage: 30 kWh
Backup goal: 50%
Battery need: 15 kWh
That would require one huge battery or two smaller ones.
Common Battery Sizes for U.S. Homes
Here’s a general guideline:
| Home Type | Battery Storage Needed |
| Small home / essential loads | 5–10 kWh |
| Average home | 10–20 kWh |
| Large home / whole-home backup | 20–40+ kWh |
Most homeowners use a series of batteries in order to achieve their wanted capacity.
How Many Batteries Do Most Homes Need?
U.S. homes install one to three batteries, which depend on:
- Backup goals
- Budget
- Energy usage
For example:
1 battery: Partial backup
2 batteries: Extended backup
3+ batteries: Entire home coverage
Cost Considerations for Battery Storage
Solar batteries can be described as a big investment.
The average cost in the U.S ranges between:
- $8,000 to $15,000 per battery (installed)
Nonetheless, incentives can be used to cut costs.
Federal Solar Tax Credit
A federal tax credit of 30 percent on battery storage is offered with solar, which reduces initial expenses by a significant margin.
Is More Battery Storage Always Better?
Not necessarily. Oversizing your battery can lead to:
- Higher upfront costs
- Underutilized storage
- Longer payback periods
The answer to this is to be able to match battery capacity to your real use, rather than the highest usage.
Should You Add Battery Storage Now or Later?
Many U.S. homeowners choose to:
- Install solar panels first
- Add battery storage later
Nevertheless, when both are installed, labor costs will be minimized and incentives maximized.
