The DC voltage of your solar power system determines the DC voltage of its system components. It will also determine the amperage capacity (ampacity) of the wires that you use. Also, it is hard to change the voltage of your system once you set it up. So, choose your system’s voltage carefully. So, keep this in mind when asking which is the better of a 24V or 48V solar system. The short answer is that the 48V system is generally better. But we should look closer to understand why.
This is the voltage of the solar system
The system voltage is the nominal voltage of the battery. It is also the nominal voltage output of the charge controller and the input to the inverter. So, a 24V system will use 24V batteries and 24V DC input into the inverter. The charge controller will output greater than 24 volts to ensure the charging of the 24V batteries. Similarly, a 48V system will use 48V components and will charge at greater than 48 volts.
Collecting energy from the solar panels
A conductor of a given diameter and type has a certain limit on the amount of amps it can safely carry. Also, the power transmitted by a conductor is equal to the voltage times the amps that it carries. So, a wire can safely handle more power using a higher voltage than a lower voltage.
A wire rated at 100 amps can transmit 4,800 watts in a 48V system. The same wire can only transmit 2,400 watts in a 24V system. The same principle applies to a charge controller. So, an MPPT charge controller with a given output amp rating can deliver twice the wattage in a 48V system as it can in a 24V system. This will allow the 48V system to handle twice the power input from solar arrays.
Storing energy in the batteries
The power (wattage) is the rate at which it can deliver energy. This means that a 48V system can deliver energy at twice the rate as a 24V system of the same amperage rating. This will let the 48V system charge the battery bank twice as quickly as the 24V system. That is if the battery bank can handle the rate of charge.
Powering the inverter
The power output from an inverter cannot be greater than its input. So, a powerful inverter will need a large power input to operate at full power. A 48V system is better than a 24V system for this because it can deliver twice the power using the same wire sizes. So many inverters rated at over 5,000 watts use 48V inputs.
Cost of wires, circuit breakers, and fuses
A 48V solar power system can use smaller components to deliver the same power as a 24V system. This includes smaller wires, circuit breakers, and fuses. This results in cheaper components.
Expandability
If a 48V system and a 24V system deliver the same power with the same size components, then the 48V system is under-used. In fact, the 48V system would only use half of its capacity. It has the capacity for more solar panels and an extra inverter. This allows you to expand your system, which helps if your needs increase.
In summary, a 48V solar system is generally better than a 24V solar system. It is because the 48V system allows more power for the same size components. This means that you can collect energy and charge batteries at a faster rate. It also allows you to use a more powerful inverter. If you use the same system power, a 48V system will either let you use smaller wires or be more expandable than a 24V system.