Microinverter Vs String Inverter: All You Need To Know 

Home Microinverter Vs String Inverter: All You Need To Know 
31/10/2022
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An electronic gadget known as a solar inverter serves as the main controller of the solar array. It resembles the “brains” of the entire apparatus. Imagine that the solar system’s photovoltaic (PV) panels as its workhorses on the roof or other property. They are responsible for converting solar energy into electrical energy by capturing it. 

However, it isn’t possible to currently use the direct current (DC) electricity that the panels generate (not counting some off-grid situations). It needs to be transformed into an alternating current before it can power the refrigerator or chill a house (AC). The direct current (DC) electricity generated by solar panels is converted into alternating current (AC) electricity using a solar inverter which is used by the appliances and HVAC systems in houses.

What is a microinverter?

Micro inverter technology
Source: Beny

To control the DC-to-AC power inversion for a single solar panel, a micro-inverter is an inverter that pairs with the panel. There is no centralized inverter in systems that use micro-inverters, which is how they vary from systems that use central inverters. Each panel is connected to a separate micro-inverter instead.

Microinverters are module-level power electronics (MLPEs) that transform the DC electricity generated by solar panels into AC electricity that can be used by home appliances and HVAC systems. They are regarded as high-tech luxury products.

To put it another way, a microinverter functions similarly to a tiny string inverter for a single PV panel that is situated on a specific panel. Prior to the inversion, they also perform DC optimization.

How does it work?

Quad-in Microinverter
Source: Beny

Each solar panel operates independently of the others when they are connected in parallel. In this setup, a microinverter mounted behind or nearby converts the solar energy generated by each individual panel from DC to AC electricity.

Modern solar microinverters optimize the solar output of each panel in your home system using MPPT and other cutting-edge techniques. This results in the best optimization and smoothest conversion.

Following the inversion, AC electricity enters your home, where it can be used to power your appliances and heat or chill the space. Anything extra is delivered to the utility grid. (Or, if one is configured to receive electrical current, to a battery pack.)

Pros and Cons of a microinverter 

Pros

Solar microinverter 1
Source: Pinterest
  • Ability to shut down quickly- They can easily and quickly shut off to comply with electrical codes in various locations.
  • Panel-wise Inspection- Microinverter performance may be monitored one panel at a time, but standard inverters can only monitor the entire system. This implies that even minor problems with the panels can be quickly found and resolved.
  • Functions well even in a shaded area -Microinverters have no trouble operating and making the most of the sunshine even in locations with partial shade and when the panels are all facing different directions because there are inverters behind every panel. Compared to an optimizer, they even have a slight advantage.

If you want to divide into the advantages of microinverters, please check out our blog on The Role of Microinverters in Photovoltaic Systems: Key Advantages Unveiled

Cons

Solar System with Microinverter technology
Source: Pinterest
  • Because there are so many inverters, maintenance is difficult.
  • When compared to a string inverter, it is not cost-effective, especially for a typical 5kW household installation.
  • Not appropriate for stormy places since microinverters may double as miniature lightning rods.

What is a string inverter?

String Inverter 1
Source: Pinterest

A central inverter with inputs for “strings” of panels to be run into a single unit is known as a string inverter. The inverter is connected to the end of a chain of connected panels that are wired in series. Multiple inputs can be seen in string inverters.

Depending on the size of the entire solar power system, each household solar installation may include just one single inverter or as many as two string inverters.

A “series string” of solar panels, also known as a group of 6 to 12 solar panels, is what a string inverter uses to operate in a series circuit.

How does it work? 

Solar panels create what is referred to as a “string” or group when they are joined in series. There may be more than one string, depending on the array’s maximum energy output and the location of the panels. One string typically consists of 8–15 panels.

All of the modules in a string must be the same type, have the same wattage rating, and face the sun at the same angle and direction in order to produce the most electricity possible.

Each string carries high-voltage DC electricity from the panels to an inverter, which is often found on the ground floor of your home adjacent to the electric panel. You can place the inverter outside, in your garage, or in the basement.

The inverter is attached to each string, typically as a separate input. You might even require more than one string inverter to manage all of the numerous strings, depending on the size and layout of your solar array. The inverter converts the DC electricity and transfers it via the strings into AC electricity.

Pros and Cons of a string inverter 

Pros

Solar String Inverters
Source: Pinterest
  • Very Few Wiring Errors- Because there is just one inverter, the wiring of the system is fairly straightforward. As a result, there is very little likelihood of wiring errors happening.
  • Cost-effective- In terms of installation costs, string inverters are fairly inexpensive.
  • Easy Problem-Solving- Installations using string inverters are fairly simple to troubleshoot because there is only one of them to deal with when there is an interruption in the production of energy.

Cons

Solar kit with String Inverter
Source: Pinterest
  • Challenges with compliance because of the slow shutdown
  • Inefficient in the shade
  • Due to the expensive expense of adding a second-string inverter, it is challenging to increase production capacity.
  • A 25-year warranty on microinverters as compared to a short warranty of 8–12 years.
  • Insufficient panel-level monitoring

Common grounds

Residential solar inverter
Source: Pinterest

Currently available residential solar inverters fall into one of three categories: microinverters; string inverters and inverters hybrids.

Whether they are grid-tied or off-grid, string inverters and microinverters share a similar trait. Both of them transform DC electricity into usable AC electricity before delivering it to your appliances.

They also direct any extra AC to the utility grid when they are grid-tied. With string or microinverters, there is no demand for onsite battery storage. (However, a battery pack connection is present for the majority of off-grid applications at least.)

As will be detailed below, string inverters differ from microinverters in terms of where the DC-to-AC conversion takes place.

Differences

Steps to Reset a Solar Inverter
Source: Pinterest

The two inverters must change from DC to AC. The location of this makes a difference. String inverters convert DC to AC at the string level, whereas micro-inverters do it at the back of each solar panel on the roof. Microinverters vs. string inverters contain some other points-

  • Production- Because of their panel-level optimization, micro-inverters frequently perform better for homes with complicated roofs and shading or soiling issues. However, due to their great efficiency, string inverters might work well for homes with a straightforward roof and decent orientation. The most recent string inverters have dual MPPT technology. 
  • Initial Cost: Compared to string inverters, micro-inverters often have greater initial equipment costs. One of the most well-liked micro-inverters has a 25-year warranty and costs around $0.7/W. With a 10-year warranty, string inverters are available for around one-third of that price.
  • Maintenance- Due to the low AC voltage they carry, micro-inverters are renowned for having a low individual failure rate. However, the failure rate rises with the number of components in a system, and a 5-kW solar system, for example, can contain 23 micro-inverters. A person needs to climb to the roof, remove the solar panels, and install a new micro-inverter when one fails. A string inverter installed on the wall eliminates the need for maintenance personnel to scale roofs.

Which one is for you?

A black soalr microinverter
Source: Pinterest

The majority of microinverter manufacturers tout extremely low failure rates, however, it continues to be dubious of these assertions. The inverter, which is the most intricate electronic component in a solar system, also happens to be the component that fails most frequently, according to sources- decades-long expertise in the solar installations industry. Instead of installing one string inverter, it would be quite hesitant to install 20 inverters. Only in extreme cases of significant shading problems it is recommended to do.

Although the ability to monitor each panel is marketed as a feature by microinverter makers (and it is), they do not offer the monitoring that enables the user to accomplish this. Unless you agree to purchase the higher level of monitoring as an upgrade, they only permit the installer to see the panel-level data from your system and not you as the client.

This implies that as a client, all of the monitoring data that is displayed to you is information about the system as a whole. A skeptic would counter that they do this in order to shield themselves and their installers from support calls relating to malfunctioning inverters. It is quite challenging to tell if only 1 or 2 inverters out of 25 or so are malfunctioning using only system-wide monitoring data.

Having said that, it is preferred microinverters, but from the view of a client, it would be preferred to buy a system with one with extra cash payment for the level of monitoring that provides panel-level analysis. The entire system pauses when a string inverter fails, which makes it easy to notice.

Conclusion

Man installing microinverter
Source: Pinterest

The limitations of your project will probably determine which type of inverter you use—micro, string, or power optimizer. If you can develop your system in direct sunlight, choose a string inverter. If you need to start small and grow later, use micro-inverters. Refer to Beny.com to get a perfect solution for your electrical system. 

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