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 advantages and disadvantages 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

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 functioning of a solar string inverter is simple. When the solar panels generate electricity, it is passed through the string inverter, which then converts it to AC energy, which appliances in the businesses can use. The string inverter also manages the voltage and current of the solar panels, ensuring that the energy produced is stable and consistent.

Advantages 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.

Disadvantages 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.

What are Micro Inverters?

A micro inverter is a small device that changes the direct current (DC) that a single solar panel makes into alternating current (AC) that your home or business can use. Micro inverters work on a per-panel basis, while traditional inverters handle power conversion for a whole spread of solar panels. This means that every panel has its own transformer, which makes them work better and use less energy.

Advantages of Micro Inverters

When it comes to optimizing each panel, microconverters are very helpful. By changing DC to AC at the panel level, microinverters make sure that a panel that is shaded, dirty, or broken doesn’t slow down the whole system. This makes it easier to collect energy and makes the system work better generally.

How Micro Inverters Enhance Efficiency

Micro inverters make the system more efficient by letting each panel work at its full potential. This is especially helpful in places where shading or changing the orientation of the panels is a problem. Individual optimization by micro inverters means that energy production is more stable and uniform.

String Inverter vs. Micro Inverter

Pros of Micro Inverters:

• Improved the system’s dependability and longevity.
• Individual panel improvement led to more energy being collected.
• Better upkeep and monitoring.

Cons of Micro Inverters:

• More expensive to buy at first than string inverters.
• The building process might be more complicated.

Pros of String Inverters:

• Less money upfront.
• For big sites, the system design needs to be simpler.

Cons of String Inverters:

• Panel mismatch leads to less productivity.
• Shade and partial system breakdowns have a bigger effect.

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.