Sizing Solar Panels for a 5kWh Lithium Iron Phosphate Battery System

Introduction

When integrating solar panels with a 5kWh lithium iron phosphate (LFP) battery system running at 48V and 100Ah, determining the correct number of panels requires careful consideration of several factors. This guide aims to provide you with detailed insights, ensuring that your setup is both efficient and effective.

Understanding the Battery System

A 5kWh lithium iron phosphate battery system with a 48V 100Ah configuration can store significant amounts of energy, making it ideal for various applications. The 48V provides a high voltage, while the 100Ah capacity ensures a substantial charge storage capability.

Electricity Needs and Load Calculation

To determine the required number of solar panels, begin by assessing your household's electricity needs. Factors such as daily energy consumption, peak load times, and desired self-sufficiency play a crucial role.

Common Daily Consumption

For an average household, daily consumption can range from 10 to 20kWh. Given the 5kWh capacity of the battery, a 50% discharge rate typically aims for a 2.5kWh charge cycle, implying a total of 2-3kWh per day.

Choosing the Right Solar Panels

Each solar panel should be around 350 watts. When connected in series, these panels can produce the necessary voltage to operate an MPPT (Maximum Power Point Tracking) charging controller at the 150 volt threshold. The MPPT controller regulates the current to the appropriate levels for charging the batteries.

Series Connection and Voltage Management

The 350-watt panels, when wired in series, will increase the voltage. A 5-panel series configuration will yield approximately 300 volts, which is well beyond the 150-volt threshold required. The MPPT charging controller will manage the current to ensure efficient charging. When the air conditioner is in operation, the system switches to bulk charging, typically at around 55 volts, allowing the sun to recharge the batteries.

Hybrid Mode and Operational Flexibility

The system operates in hybrid mode, where the sun continues to contribute to the charge during periods of usage. This hybrid mode enhances the overall efficiency of the system. Here’s how it works:

Solar Power Input: The sun generates power, which the MPPT controller captures and distributes. Usage and Charging: As you use power from the battery, the system remains charged by the sun, minimizing the need for grid power. AC Operation: Once the air conditioner is turned on, the system switches back to bulk charging, ensuring a constant supply of power.

Conclusion

Choosing the right number of solar panels for your 5kWh lithium iron phosphate battery system is critical. With the right configuration, your system can run efficiently, providing a reliable and sustainable energy source. By utilizing 4-5 350-watt solar panels in series, you can ensure that your system meets your energy needs while optimizing the use of available resources.