How to Charge 48V Battery with Solar Panels

When it comes to sustainable energy solutions, solar power is one of the most efficient and eco-friendly ways to charge a 48V battery. Whether you’re looking to power a backup system, an RV, or even your home, knowing how to charge a 48V battery with solar panels can save you both money and energy in the long run.

However, this process requires proper planning, the right equipment, and accurate configurations. In this guide, we’ll explain everything you need to know, from choosing the correct solar panel size to installation tips and calculations.

What size solar panel to charge 48v battery

Choosing the right solar panel setup involves understanding the wattage of the solar array and number of solar panels.

Size of solar panel array

To determine the size of the solar panel needed to charge a 48V battery, start by calculating the total energy required to fully charge the battery using:

• Total Energy (Wh)=Battery Voltage (V)×Capacity (Ah)

Next, divide this energy by the desired charging time, which can either be the expected charging duration or the average daily sunlight hours. This calculation gives you the solar panel power required to generate the necessary energy within the specified time frame:

• Solar Panel Power (W)=Total Energy (Wh)/Charging Time (hours)

This approach helps determine the optimal panel size to achieve the target charging output efficiently.

For instance, a 48V 100Ah battery has an energy capacity of 4.8kwh (48V×100Ah=4800Wh=4.8kWh). To charge it in 5 hours of sunlight, you'd need a 960W solar array (4800Wh / 5h). However, accounting for an additional 25% inefficiency, you would need a 1200W solar array to charge it effectively.

Number of solar panel

To calculate the number of solar panels needed, divide the total wattage required by the wattage of each panel. For instance, if you're using 300W panels, the calculation would be:

1200W/300W= 4 

So, to effectively charge a 48V 100Ah battery, you would need four 300Watt solar panels, assuming optimal sunlight conditions.

Installation tips for charging 48v battery with solar panel

Can You Charge a 48V Battery with a 12V Solar Panel?

Charging a battery with a solar panel lies in the flow of electrical current, which moves from a higher voltage source to a lower voltage destination. For the battery to charge effectively, the solar panel's voltage must be higher than the battery's voltage.

So, technically, you cannot charge a 48V battery directly with a 12V solar panel unless you connect four 12V solar panels in series to exceed the battery’s charging threshold, which is generally around 54-60V for lithium-ion batteries.

If possible, it is recommended to use a solar panel whose voltage matches the 48V battery's charging voltage, as this simplifies the setup and avoids potential issues.

Additionally, if you have limited space to install multiple solar panels, a boost charge controller can step up 12V to the required 48V.

Use a solar charge controller

Charging a 48V battery with such a high voltage will damage the battery and pose safety risks. The solution here is to use an MPPT charge controller, which can regulate the high voltage from the solar panel down to the safe operating range of the 48V battery.

When install a solar charge controller, please keep in mind that wiring should follow the sequence of Battery > PV Input > Load, to avoid damage.

Adjust the connection of solar panels

Choosing the right voltage ensures compatibility with the battery and optimizes charging efficiency. Always use a charge controller to regulate the system and protect the battery from overcharging or damage.

Additionally, configure the solar panel system in parallel or series connections as needed to align with the solar charge controller's input requirements.

How to charge a 48v lithium battery

Batteries are charged in multiple phases: bulk, absorption, and float. Each phase has a specific voltage range to optimize charging, protect the battery, and ensure longevity. Therefore, it is crucial to configure the charging parameters according to the battery's specifications.

How many cells are in a 48v battery

Additionally, it’s important to know whether your 48V battery is 15S or 16S. Most 48V batteries on the market consist of 15 or 16 cells, depending on the model.

For example, lithium-ion cells typically have a nominal voltage of 3.2V (LiFePO4) or 3.7V (NMC). A 15S configuration gives you about 48V (15 × 3.2V = 48V), while a 16S setup provides a slightly higher voltage (~51.2V). Knowing your battery's configuration is essential, as the charging voltage differs between 15S and 16S batteries.

48V LiFePO4 Battery Voltage Chart

SoC is often determined using voltage levels, with specific ranges corresponding to various charge levels.

The table below provides a general reference for the voltage of 48v batteries based on their state of charge (SoC).

State of Charge (SoC)	15 cells LiFePO4	16 cells LiFePO4
Full Charge	54.75V	58.4V
90%	53.2V	56.4V
80%	52.4V	55.6V
60%	51.6V	54.6V
50%	51.2V	54.2V
30%	50.2V	53.0V
20%	49.6V	52.4V

Key charging parameters of 48v battery

When setting up a charging system for a 48V lithium battery, proper configuration of charging parameters is crucial to ensure safe and efficient operation. Below are the main parameters to set, their definitions, and their importance.

For example, consider the specifications of the PowMr POW-LIO48100-16S battery:

• Maximum Discharge Cutoff Voltage: 43.2V (lower limit)
• Recommended Discharge Cutoff Voltage: 48V

This 48V battery consists of 16 cells, with a full charge voltage of 58.4V based on the specifications above. Therefore, the float or trickle charge voltage can be set to this value (58.4V).

To prevent deep discharge, which can degrade the battery, it’s best to recharge it when the State of Charge (SoC) drops to 20%. To achieve this, set the discharge cutoff voltage to 52.4V, ensuring it stays within the recommended range, with the lower limit at 43.2V (maximum discharge cutoff voltage

By following these guidelines further, you ensure optimal charging, battery performance, and longevity:

How Many Amps to Charge a 48V Battery Bank?

The charging current depends on the battery’s capacity and recommended charge rate. For the PowMr 100Ah 48V battery:

• Recommended Charging Current: 20A (0.2C rate)
• Maximum Current: 100A

On the other hand, you can adjust the charing current segun your expected chaging time, just keep it below the max charging current by the manufacture.

To determine the charging current for a specific charging time, use the formula:

• Charging Current (A)=Battery Capacity (Ah)/Charging Time (hours)

For example, if the battery capacity is 100Ah and you want to charge it in 4 hours, the charging current would be 25A (100Ah/4h)

Always ensure the calculated current is within the manufacturer's limits. For example, the PowMr 100Ah 48V battery recommends a maximum charging current of 100A, making 25A safe for use.

For efficient 48V battery charging, the PowMr M60-Ultra MPPT controller offers configurable currents (2A–60A), compatibility with 48V systems, and enhanced solar efficiency through advanced MPPT technology, ensuring optimal performance and energy utilization.