Battery Storage
Battery Storage refers to the use of rechargeable batteries to store electricity generated by a solar PV system for later use. It allows homeowners, businesses, and utilities to save excess energy produced during the day and use it during the night, during grid outages, or when utility rates are high.
In modern solar systems, battery storage is one of the fastest-growing technologies due to rising electricity prices, demand for backup power, grid instability, and the expansion of time-of-use billing. Storage systems are often integrated into solar design workflows through tools like Solar Designing, and energy modeling becomes more accurate with shading and irradiance insights from Shadow Analysis.
Battery storage is essential for residential, commercial, and utility-scale solar applications—supporting energy independence, resilience, and peak load reduction.
Key Takeaways
- Battery Storage allows solar energy to be used when sunshine isn’t available.
- Enhances energy independence, resilience, and cost savings.
- Works with solar panels, hybrid inverters, and smart controls.
- Essential for backup power, TOU optimization, and grid services.
- Integral to modern solar workflows using automated design tools and planning platforms like SurgePV.
What Is Battery Storage?
Battery Storage is an energy system that captures and stores electricity so it can be used later. In a solar PV setup:
- Solar panels produce DC power
- Batteries store DC electricity
- Inverters convert DC to AC for use or export
Battery storage makes solar systems flexible and reliable, helping users power critical loads, avoid peak electricity charges, and maintain uptime during grid disruptions.
Battery systems are central to modern hybrid and off-grid solar design and are commonly paired with load analysis, inverter sizing, and system optimization tools like Solar Project Planning Hub.
How Battery Storage Works
1. Solar Panels Produce DC Electricity
Energy is generated during sunny hours, often exceeding real-time consumption.
2. Excess Energy Charges the Battery
Instead of exporting all surplus energy to the grid, batteries store it for later use.
3. Inverters Manage Power Flow
Hybrid or battery inverters decide when to charge, discharge, export, or power loads.
4. Stored Energy Powers the Building
At night, during outages, or during peak pricing windows, the battery supplies electricity.
5. Smart Controls Optimize Use
Advanced systems use load forecasting, rate schedules, and production estimates for maximum savings.
Related concepts include Load Analysis and Inverter Sizing.
Types / Variants of Battery Storage
1. Lithium-Ion Batteries (Li-ion)
The most common type for residential and commercial solar.
Benefits: high efficiency, long lifespan, compact size.
2. Lithium Iron Phosphate (LFP)
A subtype of lithium-ion known for excellent safety and thermal stability.
3. Lead-Acid Batteries
Older and more affordable, but bulkier and less efficient.
Used mostly in off-grid or backup-only scenarios.
4. Flow Batteries
Ideal for utility-scale energy storage.
Long duration, high cycle life, and tolerance for deep discharge.
5. Hybrid Battery Systems
Integrated with hybrid inverters for seamless solar + storage operation.
6. Utility-Scale Battery Energy Storage Systems (BESS)
Massive storage banks used for grid support, peak shaving, and renewable integration.
How Battery Storage Is Measured
Battery performance and size are defined by:
Capacity (kWh)
Total amount of energy the battery can store.
Power Rating (kW)
Maximum amount of energy the battery can deliver at once.
Depth of Discharge (DoD)
Percentage of the battery’s capacity that can be safely used.
Round-Trip Efficiency (%)
Energy retained after charging and discharging.
Cycle Life
Number of charge-discharge cycles before degradation.
State of Charge (SoC)
Current stored energy level—related to SoC.
Typical Values / Ranges
Practical Guidance for Solar Designers & Installers
1. Start with load analysis
Use tools like Load Analysis to identify critical loads and backup needs.
2. Size the battery based on goals
Common objectives include:
- Backup power
- Peak shaving
- Self-consumption
- Off-grid independence
3. Evaluate inverter compatibility
Hybrid inverters simplify installation and system management.
4. Consider TOU billing schedules
Storage provides maximum value where electricity rates vary throughout the day.
5. Perform accurate production modeling
Integrate shading results via Shadow Analysis for correct sizing.
6. Use design automation tools
Auto-layout and inverter sizing features inside Solar Designing speed up project workflows.
7. Ensure proper ventilation and placement
Batteries should be installed in cool, dry, indoor/covered environments for longevity.
Real-World Examples
1. Residential Solar + Battery
A 10 kWh LFP battery powers a home during evening peak rates and provides overnight backup for essential loads.
2. Commercial Demand Charge Management
A grocery store installs a 200 kWh battery to reduce monthly demand charges and stabilize power usage.
3. Utility-Scale BESS
A 50 MWh battery system stabilizes grid frequency, supports solar farms, and reduces curtailment during high-supply periods.
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