Solar inverters change the DC electricity that is produced by solar panels in to AC electricity that is used by homes and buildings. Three technologies are available for installation: String Inverters, Micro Inverters, and DC Optimizers. You may have only heard of one or two of these technologies. This article is to help our customers better understand their inverter options.
Before we discuss the different types of inverters available, you first need to understand what an inverter does:

• Solar modules output Direct Current Electricity
• Inverters change DC Electricity to Alternating Current (AC) electricity.
• …More information on how solar energy works.

 

String Inverters

String inverters are the traditional inverter used in solar installations. They work great in applications with limited shading and consistent soalr panel orientation. New Dual Mppt units can be designed to work with dual orientation’s and slightly shaded conditions. Below is a quick explanation on solar string inverters:

1. Solar panels are wired in series to form a string of modules.
2. A single string of modules is then combined or ran by itself to the string inverter.
3. The DC electricity from the solar modules is then inverted in to AC electricity.

 

Benefits of a String Inverter:

• Lower cost than micro inverters.
• Less points of failure
• Easy maintenance.
• Great for large gable roofs.
• Proven technology that has been around for years.
• High Efficiency

 

 

Micro Inverters

Micro Inverters are the younger solar inverter technology. Below is a quick explanation of how they work:

• Micro Inverters attach to the racking (mounting) equipment directly below the solar module.
• Each module has its own micro inverter.
• Micro Inverters are then wired together and ran to an electrical panel.

 

Benefits of Micro Inverters:

• Solar module performance is no longer limited by shaded neighbor modules.
• Great for irregular roofs.
• Monitoring system provided allows for module monitoring.
• Safer for fire department to cut into roof.
• Rapid Shut down compliant

 

 

DC Optimizers

DC Optimizers are a new technology that utilizes ideas from string and micro inverters. Below is a quick explanation of how they work:

• DC optimizers attach to the racking (mounting) equipment directly below the solar module.
• Each module has its own optimizer that regulates the DC output of the module.
• The Optimizers are wired in to a string and fed in to a string inverter that communicates with the optimizers.

 

Benefits of DC Optimizers:

• Solar module performance is not limited by shaded neighbor modules.
• Voltage limiting allows for longer strings
• Monitoring system provided allows for module level monitoring.
• Safer for fire department to cut into roof.

 

 

Final Thoughts

We strongly encourage string inverters when designing systems with limited shading. String Inverters reliability and ease of maintenance make them the safest choice for system design. Micro Inverters are a safe alternative for systems where modules can be maintained from underneath (ground mount and tilt leg). DC optimizers are a safer bet for roofs than micro inverters because they contain less electronics inside the rooftop unit.

Solar Panels are expected to last 30+ years, however, inverters are not. Inverter’s have an estimated life expectancy of 10 to 20 years. This is the underlying reason designers at HESOLAR recommend string inverters when possible. We have additional pages available on solar inverters.

Hopefully this gives you a better understanding of the available inverter options. Of course, you can always leave it to us to determine what options best fits your needs.

(Archived from HESOLAR original website – content has been updated and is still relevant)
written by: Eric Hoffman May 23, 2012
edited February 4, 2015