String Inverters, Micro-Inverters and String Inverters

String Inverters, Micro Inverters and Optimizers

Solar inverters serve a single purpose: to convert the Direct Current (DC) generated by solar panels into the Alternating Current (AC) used in your home.
Over the last several decades, inverter technology has constantly improved, allowing homeowners to get the most out of their solar panels. As a solar homeowner, both string inverters and micro-inverters do this function, albeit in different ways.

What is a microinverter?

Micro-inverters are similar to string inverters in operation, however, they are positioned beneath each solar panel on your roof. Each microinverter is around the same size as an internet router.

Micro-inverters and string inverters differ significantly in that a solar panel system using microinverters will normally have the same number of microinverters as solar panels (Note: some microinverters accept two or four solar panels).

Enphase is a renowned microinverter maker. Enphase microinverters have been on the market since 2009 and have been a key component of their rapidly expanding business. Their scientists have been researching how to best use maximum power point tracking (mppt) concepts into their components to boost solar PV production.

Micro-inverters, on the other hand, do not have this difficulty because they operate in a parallel circuit, unlike ordinary string inverters, which cap the electricity production of each panel by the lowest producing panel on your roof.

The production of each panel will be fully used by a microinverter. The power generated by each panel will be converted to grid voltage using this device. Each solar panel and microinverter combo may “give it their all” and provide as much power as possible.

Advantages of microinverters

  • Because each Solar Panel produces independently of the others, a Solar Panel’s performance has no bearing on the performance of its neighbors. As a result, the performance of other solar panels will not be harmed by a shaded solar panel because they operate independently. String Inverters are an exception to this rule.
  • These inverters are small enough to put in the back of a solar panel. Because of its small size, it does not require as much cooling as central inverters. As a result, there is less heat loss.
  • A broken solar panel or inverter has no effect on the generation of solar energy from other panels, but a broken Solar String or Central Inverter will bring the entire array to a standstill.
  • In a Micro-Inverter architecture, the output from each Solar Panel and the Micro Inverter is typically monitored via a communication channel, which allows for much faster isolation of a problem than with other inverters.
  • Because the output is converted from DC to AC (230V) at the back of the panel, the current-carrying wire can be smaller.
  • A solar system may readily extend from a single panel to several panels that are independent of each other due to its modularity.

Disadvantages of microinverters

  • A Micro Inverter’s biggest downside is its greater starting cost. However, in circumstances where there are technical difficulties in building a solar array (series of solar panels) or shading issues that could cause the entire system to underperform, its expense can be justified.
  • Because each inverter is installed separately beneath a solar panel, a communication bus and a common monitoring system are required, similar to string inverters, which include an onboard display system.
  • Due to current site conditions, replacing the micro inverter, which is located underneath the solar panel, maybe challenging and require more than one expert on site.

What is a string inverter?

A string inverter (sometimes known as a “central inverter”) is a stand-alone box located near your main service panel and electricity meter.

Each household solar installation normally has only one single inverter, or sometimes two string inverters, depending on the overall solar power system size.

A string inverter works in a series circuit, with a “series string” usually consisting of 6 to 12 individual solar panels.

Advantages of using string inverters

  • The majority of the string inverters are located on the wall in a common room. This makes maintenance easier because it eliminates the need to return to the field for troubleshooting. This is a significant advantage in areas with extreme cold or heat.
  • String inverters, as previously said, have been around for decades. As a result, most string inverters are dependable, and electricians are familiar with the technology.
  • String inverters are currently less expensive than microinverters in terms of cost. One string inverter is required per installation, whereas micro inverters require one inverter per panel.

Disadvantages of string inverters

  • The entire solar array will be rendered inoperable if the inverter fails. This could result in a major reduction in electricity generation.
  • Expandability in the future is limited unless you purchase an oversized string inverter, as once installed for a specific rating, the inverter’s rating cannot be changed. In this situation, you’ll need to purchase a second inverter.

What are power optimizers? 

Power optimizers are positioned at each solar panel and provide a hybrid solution between a typical string inverter and microinverters.
The power optimizers “condition” the electricity generated by your solar panels by optimizing the voltage before sending it down to the inverter for conversion. Importantly, power optimizers are not inverters in and of themselves; they must be used in conjunction with a centralized string inverter to complete the conversion process.

Because power optimizers are located at the panel site, they each have their function in the system. As a result, MLPEs such as power optimizers are the best choice for complex installations or those with minor shading.
When using a typical string inverter without MLPEs, the panels can only produce as much power as the string’s worst-performing panel. When you link the inverter with power optimizers, this isn’t a problem: because solar panels have their MLPE component, they’ll continue to work efficiently even if one of the panels in the system isn’t providing electricity.

Advantages of Design with DC Power Optimizers:

  • In comparison to microinverters, there is a lower starting cost because one optimizer can be shared by one or more solar panels, as well as the cost savings of employing a single string inverter.
  • DC power optimizers, like microinverters, isolate each panel from the rest of the system, optimizing generation while reducing shade and mismatch concerns.

Disadvantages of Design with DC Power Optimizers:

  • When compared to microinverters, high voltage DC is not reduced on the roof.
  • DC optimizers must be designed to meet the maximum panels per string on string inverters, making them less versatile than microinverters.
  • When opposed to microinverters, they are less robust since if one optimizer fails, the entire string fails. In addition, when compared to microinverters or string inverters, the number of failure spots is larger.

Now we believe you understand what are String Inverters, Micro Inverters and Optimizers

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