Which is Better – Solar String Inverter VS Central Inverter

When it comes to solar panel systems, two of the most popular inverter types are the solar string inverter and the central inverter. Both have their pros and cons when it comes to design, cost, and efficiency. Knowing these differences can help you make an informed decision that best fits your energy needs. This article will compare the two inverters in detail to provide a better understanding of which one is best for you.

Solar string inverters are electrical devices that convert the direct current (DC) generated by solar panels into alternating current (AC) that businesses can use. They are usually installed in a string formation where multiple solar panels are connected in series to form a single circuit. The solar energy produced by the panels is then fed into the string inverter, which converts the DC energy into AC energy, making it usable by businesses and industries.The string inverter also manages the voltage and current of the solar panels, ensuring that the energy produced is stable and consistent.

Upsides of Solar String Inverters

• Cost-effective: Solar string inverters are the most cost-effective inverters available today. They are less expensive than other inverters, such as micro-inverters, which can be costly due to their unique panel-level design.
• Efficiency: String inverters are also more efficient than microinverters. They can convert DC energy into AC energy at an efficiency rate of up to 98%, higher than microinverters.
• Easy to maintain: Solar string inverters are easy to maintain as they are installed in a central location, making it easy to monitor and troubleshoot any issues.
• Scalable: String inverters can be easily scaled up or down to meet the needs of the business.

Downsides of Solar String Inverters

• Limited performance monitoring: String inverters have limited performance monitoring capabilities compared to microinverters. They do not provide individual panel-level tracking, making it challenging to identify the performance of individual panels.
• Reliability: String inverters have a higher risk of failure than microinverters. If one panel fails, it can affect the entire string’s performance, reducing the overall energy production.
• Space requirement: String inverters require more space for installation compared to microinverters. This can be a challenge for businesses with limited space.

Central Inverters

Central inverters are large devices used in solar power plants to convert the direct current (DC) produced by solar panels into alternating current (AC) that can be fed into the electrical grid. They are usually installed outdoors and are designed to withstand high power.

Central inverter functioning is designed to operate at a fixed voltage and frequency. They use electronic components such as MOSFETs, IGBTs, and diodes to convert direct and alternating currents. The direct current produced by the solar panels is first fed to a combination box where several panels are connected in parallel. The combined DC output from the combo box is then fed to a central transformer, which converts the DC into an AC source that can be fed into the mains. The output voltage and frequency of the central inverter are synchronized with the grid voltage and frequency.

Advantages of Central Inverters

• High efficiency: Central inverters are very efficient, with conversion efficiency ranging from 95% to 98%. This means they can convert much of the direct current produced by the solar panels into alternating current electricity fed into the grid.
• Cost-effective: Central inverters are cost-effective, especially in large solar power plants. Their cost per watt is lower than micro-inverters or string inverters.
• Easy maintenance: Central inverters are easy to maintain and have fewer parts to replace. They also have a longer lifespan, so they must be replaced less often.

Disadvantages of Central Inverters

• Single Point of Failure: Central inverters are a single point of failure in a solar power plant. If the central converter fails, the whole system goes down.
• Limited flexibility: Central inverters have little flexibility in terms of power management. They cannot control power on a per-panel basis, meaning blackouts or failures in one panel can affect the entire system’s performance.
• Size and weight: Central inverters are large and heavy, making installation and maintenance difficult. A separate space is also required for their installation.

Power Output

Solar inverters are designed for a specific number of solar panels or “strings.” A string is a series of interconnected solar panels. The number of strings to connect to the solar inverter depends on the power of the inverter. Solar inverters are usually available in capacities from 1 KW to 10 KW. The number of strings connected to the inverter varies between 1 and 3.

The Central Inverter, on the other hand, is designed for larger solar systems. It can handle more strings and is more powerful than a string inverter. Central inverters are available in sizes from 10 KW to 500 KW and can handle up to 16 strings. The inverter’s maximum and minimum KW and strings are important factors to consider when choosing an inverter for your solar system. The Max KW value indicates the total power that the inverter can handle. The minimum KW value indicates the minimum energy required for the inverter to operate efficiently.

Parting Thoughts

After carefully analyzing the differences between Solar String Inverters and Central inverters, it is evident that both have their unique features and advantages. The choice between the two ultimately depends on your solar panel system’s specific requirements and constraints.

Solar string inverters are best suited for solar systems with fewer than 15 panels. They offer high efficiency, easy maintenance, and a relatively lower cost. On the other hand, central inverters are more suitable for larger commercial or industrial solar systems with 15 or more panels. They offer better reliability, higher power output, and a longer lifespan.

The decision between solar string inverters and central inverters will depend on your solar panel installation’s size, complexity, and budget. However, regardless of the type of inverter chosen, it is important to ensure that it is installed and maintained by a qualified professional to ensure optimal performance and longevity.