Battery Storage
Battery Sizing Calculator
Calculate battery storage needs for your home — instant results, no signup required.
Calculate Battery Size
Battery Sizing Calculator: How Much Storage Do You Need?
Use this battery sizing calculator to find the right battery capacity for your home. Enter your daily energy usage, solar system size (or 0 if no solar yet), and desired backup duration to get an instant recommendation — including how many Tesla Powerwalls you need and estimated installed cost.
Home battery storage is one of the fastest-growing home energy investments in the US. Power outages are increasing nationwide, electricity rates are rising 3–5% per year. Note: the federal 30% residential ITC expired December 31, 2025 — state incentives remain active in many markets.
How to Use the Battery Sizing Calculator
Daily Energy Usage (kWh/day): Check your electricity bill for your average daily kWh. The US average is about 30 kWh/day. If you only want to power essential loads during an outage (refrigerator, lights, WiFi, medical devices), enter 30–40% of your total usage — typically 10–12 kWh.
Solar System Size (kW): Enter your existing or planned solar system size. If you don't have solar, enter 0. Adding solar to a battery system changes the calculation significantly — with solar, your battery recharges daily for potentially indefinite backup.
Backup Duration: Enter how many hours of backup you want. 24 hours covers most short outages. 72+ hours provides protection for multi-day outages common in hurricane or ice storm zones.
Grid-Tied vs Off-Grid: Which System Is Right for You?
Grid-Tied Battery System
Stays connected to the utility grid. Stores solar energy and discharges at night or during peak pricing hours. During outages, automatically switches to battery power and recharges with solar. Most common and cost-effective setup for most homeowners.
Off-Grid Battery System
Operates completely independently of the utility grid. Requires significantly more battery capacity (3+ days of autonomy) and a large enough solar array. Off-grid systems cost more but are essential for remote properties without grid access.
Battery Storage Costs in 2026
The most popular home battery is the Tesla Powerwall 3 at 13.5 kWh, costing approximately $9,500–$11,500 installed in 2026. State incentives like California's SGIP can significantly reduce net cost — see our Battery Incentives Guide.
Tesla Powerwall 3
Enphase IQ Battery 5P
LG RESU 16H Prime
Solar + Battery: The Best Combination
Pairing solar panels with battery storage gives you the maximum benefit: free solar energy during the day, stored power at night, and backup protection during outages. With solar, your battery recharges daily — turning a single-use backup device into a permanent energy savings system. Learn more in our Battery Basics Guide or use our Solar Savings Calculator for the complete solar + storage picture.
Quick FAQs
Can I add a battery to my existing solar system?
Yes — most modern inverters support AC-coupled battery storage. A solar + battery retrofit typically costs $10,000–$20,000 installed before incentives.
How long do home batteries last?
Most home batteries carry a 10–15 year manufacturer warranty and are rated for 4,000–6,000 charge cycles. Real-world lifespan is typically 15–20 years with proper management.
Your Battery Backup System
Customized for your energy needs
Recommended Battery Size
— Battery storage needed🔋 Tesla Powerwalls
— 13.5 kWh each⚡ Enphase IQ 5P
— 11.5 kWh eachEstimated Runtime
— hours of backup power☀ With Solar
— recharges daily🔌 Grid Only
— per charge cycleGet Quotes
Compare 3–5 local battery installers. Read our Battery Basics Guide first.
Check Incentives
Consider Solar
Maximize savings with solar panels. Try our Solar Calculator.
Additional resources: Energy.gov Battery Storage Guide
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