Are you considering installing a solar system but feeling confused about the different inverter options? We are often asked what the differences are and “Why would I opt for one over the other”? With years of experience in installing solar systems, let us break this down for you.

At Lenergy we offer all 3 types of inverters because we know every household has its own needs and requirements. 

In this article we will compare String Inverters, DC Optimised systems, and Microinverters; examining their efficiency, installation, cost, and suitability for various scenarios. Choosing the right system is crucial for maximising your system’s efficiency and cost-effectiveness. 

By the end, you’ll have a clear understanding of which system will suit your needs best, ensuring optimal performance and value from your solar investment.

What are String Inverters?

String inverters dominate the solar energy market, due to their cost-effectiveness. They work by connecting a series (or string) of solar panels to a single inverter. This inverter converts the DC electricity from the panels into AC electricity. AC electricity is what powers your household appliances and the grid.

Advantages of String Inverters:

1. Cost-Effective: String inverters are generally less expensive than other types of inverters. Their lower cost makes them an attractive option for small to large-scale installations.
2. Simplicity: String inverters offer a more straightforward installation in comparison to DC optimisers or microinverters. 
3. Efficiency in Ideal Conditions: In ideal conditions, all panels get equal sunlight without shading. In these conditions, string inverters can be very efficient.

Disadvantages:

1. Shading: If one panel in the string is shaded, soiled, or damaged in any way, the system’s output can be drastically reduced. This is because the power output of the entire string is affected by the weakest panel.
2. Limited Monitoring: String inverters typically offer less detailed monitoring of individual panel performance. This can make it harder to identify and address issues with specific panels.
3. Limited Design Flexibility: String inverters require panels in a specific layout. This limits design flexibility, especially on roofs with multiple orientations or obstructions.

Best Use Cases:

• String inverters are ideal for open spaces with little or no shading. These include homes with simple roof designs that are unaffected by shading, large commercial rooftops or ground-mounted solar farms.
• Simple Panel Layout. They work well for homes with very simple roof layouts where the solar panels only face up to three separate directions.
  

String inverters are reliable and cost-effective for many solar installations. But, shading and layout can greatly hurt their performance.

Imagine a large, open roof with no shading, this is where string inverters thrive.

What are DC Optimisers?

DC optimisers are advanced devices paired with each solar panel in a system, still working with a central string inverter. Their main job is to maximise the energy output of each panel by conditioning the DC electricity before it reaches the inverter. Each optimiser is attached to a single solar panel, independently optimising the panel’s performance. This allows each panel to operate at its maximum potential, regardless of the performance of surrounding panels.

Additionally, DC optimisers adjust the DC voltage to ensure the inverter receives the ideal voltage for converting to AC. This panel-level optimisation enhances the overall efficiency and reliability of the solar energy system.

Advantages:

1. Better Shading Performance: DC optimisers reduce shading’s impact on a solar array. They do this by ensuring that the other panels in the string keep operating at their best. This results in improved overall system efficiency compared to traditional string inverters.
2. Panel-level Monitoring: It allows for precise issue detection and performance tracking for each panel. This makes maintenance more targeted and efficient.
3. Higher Harvest: DC optimisers can increase the total energy that solar panels harvest. They do this by ensuring each panel runs at its best. This is especially helpful in systems with partial shading or varied panel orientations.

Disadvantages:

1. Higher upfront cost: Adding DC optimisers raises the initial cost of the solar installation. It raises it compared to a system with only a string inverter.
2. Added Install Time: The installation process has a few more steps with the added DC optimisers. This can increase the installation time. This is dependent on the complexity of the installation.

Best Use Cases:

• DC optimisers are for places where some panels may be slightly shaded at different times of the day. This includes residential rooftops with chimneys, trees, or other obstructions that may shade sections of the roof.
• Variable Panel Orientations are well-suited for roofs with many angles or orientations as each panel can be optimised separately.

DC optimisers offer a great balance of cost and performance. They boost the efficiency and reliability of solar systems in less-than-ideal conditions. They provide great benefits in scenarios where shading or panel orientations would otherwise reduce the system’s overall output.

What are Microinverters?

Microinverters are small inverters attached to each solar panel in a solar energy system. Unlike string inverters, which convert the DC electricity of an entire array, microinverters convert the DC to AC at the panel level. Each microinverter is installed on a solar panel, converting its DC electricity to AC electricity on the spot.

This panel-level conversion allows each panel to operate independently, ensuring optimal performance regardless of issues with other panels. By enabling independent operation, microinverters ensure that the performance of one panel does not affect the others, enhancing the overall efficiency and reliability of the solar energy system.

Advantages: 

1. Maximum Efficiency: By converting electricity at the panel level, microinverters ensure that each panel operates at its maximum potential. This leads to higher overall system efficiency, especially in systems with shading or varying panel orientations.
2. Excellent Performance in Shaded Conditions: Because each panel operates independently, shading on one panel does not affect the performance of the rest of the system.
3. Enhanced Monitoring: Microinverters offer detailed monitoring of each panel’s performance, allowing for precise identification and troubleshooting of issues.
4. Increased Safety: With no high-voltage DC running through the system, microinverters reduce any risk of electrical fires.

Disadvantages:

1. Cost: Microinverters cost more upfront. 

Best Use Cases:

• Complex Roof Designs: Microinverters are ideal for installations with multiple roof angles and orientations, as they ensure each panel performs optimally regardless of its position.
• Shaded Locations: They are perfect for areas where shading varies throughout the day, as each panel operates independently without impacting the rest of the system.
• High-Performance Monitoring: For those who value detailed performance data, microinverters provide comprehensive monitoring at the panel level, making them a great choice.

Microinverters are very efficient and flexible. Microinverters are an excellent choice for residential and commercial solar installations with varying conditions. Their ability to optimise each panel independently and provide detailed monitoring ensures maximum energy production and system reliability.

How are DC Optimisers, String inverters and Mircoinverters Different?

Choosing between String Inverters, DC optimisers, and Microinverters involves evaluating many key factors. These include efficiency, performance, installation, maintenance, cost, and safety. 

Here’s a detailed comparison to help you understand the differences:

Efficiency and Performance:

• String inverters are efficient in ideal conditions. But, they suffer performance drops if even one panel is shaded or malfunctioning. The output of the whole string is limited by the weakest panel. It can greatly reduce efficiency.
• DC optimisers boost efficiency. They do this by letting each panel operate at its best. They reduce the impact of shading on a single panel. They do this by optimising each panel independently. This results in better overall system efficiency in varied shading conditions.
• Microinverters offer the highest efficiency. They convert DC to AC at the panel. Each panel operates alone. If one panel is shaded or fails, it does not affect the others. This results in superior performance, particularly in installations with mixed shading or orientations.

Installation and Maintenance:

• String Inverters: These are the simplest and quickest to install due to fewer components. Maintenance is also straightforward, as there is only one central inverter to manage.
• DC Optimisers: Have more time-consuming installations. This is due to the extra components attached to each panel. Maintenance can be more involved. But, the panel-level monitoring makes it easy to find and fix specific issues.
• Microinverters: Much like the DC Optimisers, are more time-consuming to install. This is because each panel requires its own microinverter. However, this allows for easier maintenance and troubleshooting at the individual panel level.

Cost Considerations:

• String inverters: Have the lowest upfront cost. This makes them a good option for budget-conscious installations. However, potential performance losses due to shading can impact long-term savings.
• DC Optimisers: Higher initial cost than string inverters due to the added optimisers. The better efficiency and performance in shaded conditions can justify the additional expense over time.
• Microinverters: The highest initial cost due to the need for multiple inverters. The higher upfront cost can be offset by better efficiency, performance, and monitoring. This is especially true in challenging installations.

Cost Comparison of a String inverter, Microinverter and DC optimisers:

– 6.6 kW String Inverter system at Lenergy is: $6,992

– 6.6 kW DC Optimiser inverter system at Lenergy is: $8,110

– 6.6 kW Microinverter system at Lenergy is: $10,279

There is a notable price difference between string inverter systems and microinverter systems. Therefore, it is crucial to have a system that is specifically tailored to your needs.

Safety and Reliability:

• String Inverters are reliable but considered less safe as high-voltage DC electricity runs through the system. Performance issues with a single panel can affect the entire string. Both String and DC optimisers have Arc Fault Detection Devices to minimise their risk.
• DC Optimisers increase safety by reducing the impact of shading and managing voltage at the panel level. They offer better reliability through panel-level optimisation. 
• Microinverters provide the highest safety. They eliminate high-voltage DC electricity, reducing the risk of fires. Their independent operation of each panel ensures excellent reliability and safety.
  

Solar inverters: turning the ‘current’ situation around

The most important takeaway is understanding your needs, your home’s capabilities, and your goals. This will help you avoid buying something unnecessary or unsuitable.

We get it, you’re probably not 7 feet tall with a perfect view of your roof. That’s why we can show you, in real time, any shading issues and discuss which option is best for your roof layout.

With the above information in your arsenal, you can now understand why one inverter option may be suggested for you. Or know if you’re being led astray.