Pros & Cons: Solar Microinverter vs Inverter

This blog will explain the similarities and differences between solar microinverter vs string inverter, as well as their pros and cons.

Both microinverters and string inverters change the Direct Current (DC) generated by the solar panels to Alternating Current (AC) to power the electrical loads. However, the type of inverter chosen will affect the cost, power output, and monitoring of the solar system.

Understanding the features and applications of Solar microinverters and String Inverters respectively are essential for making well-informed decisions when it comes to choosing a suitable inverter. 

What are String Inverters? How do they work?

String inverters connect multiple solar panels in series to form a “string”. The DC power generated by each panel is combined and channelled into the inverter – allowing the string inverter to convert DC power from the solar panels into AC power for electrical loads.

The string inverters typically come as a single unit to convert generated DC power from multiple solar panels into AC power for usage. Most string inverters have monitoring capabilities like Maximum Power Point Trackers (MPPTs) to track the performance of the solar energy system in real-time.

What are Microinverters? How do they work?

Microinverter is another type of PV inverter which is typically installed on individual solar panels. Similarly, microinverter converts DC power from solar panels to AC power for electrical loads. The difference is that a microinverter is a type of Module-Level Power Electronics (MLPE) that optimises individual solar panels' efficiency. In contrast, string inverters are normally paired with optimisers to conduct module-level optimisation and monitoring of solar panels. Both have their advantages and disadvantages when it comes to installation, monitoring, and maintenance of the solar system.

Differences between Microinverters and String Inverters

Both string inverters and microinverters work by converting DC power to AC power. The main difference between the two types of inverters lies in what type of locations they are meant to be installed: smaller homes are generally better suited for microinverters, while larger commercial premises would typically go with string inverters to accommodate more solar panels.

Size

The physical size of the microinverter, as the name implies, is much smaller than a string inverter. Often, the microinverter is mounted below each solar panel to enable module-level monitoring and optimisation. The inverter is typically small enough to be hidden below a solar panel, making it ideal for smaller households.

Larger residences and commercial buildings with more space typically have more solar panels installed to generate more power. String inverters would be a better option for these kinds of locations because multiple solar panels can be connected to a single string inverter by wiring them together. Therefore, choosing between a string inverter or a microinverter depends on the size of the customer's rooftop.

Installation

Both Microinverters and String Inverters are convenient to install in their ways. The under-panel placement and light weight of the microinverter make it easy to install. Although String Inverters are typically bulkier than Microinverters, the installation can be easier for larger solar systems - more than one solar panel can be connected to a single string inverter. After all, customers are advised to select a microinverter or string inverter according to the number of solar panels in the household/business premises.

Point of DC to AC Conversion

Microinverters convert electrical current at the source of creation (solar panel), whereas string inverters convert electrical current from all solar panels in one central location. Hence, it is typical for string inverters to have higher power capacity than microinverters, as they need to handle a larger amount of DC input.

Pros and Cons of Solar String Inverters vs Microinverters

Ease of installation

Both are simple to install in their respective ways. The size of the solar system makes all the difference; microinverters work best with smaller solar systems since installers and homeowners can mount the lighter microinverter beneath the solar panel to generate power. Larger solar systems typically require higher-powered string inverters, which weigh more than microinverters. However, installers and homeowners can save time during installation by only installing one string inverter to convert all the power output from all panels in one central location.

Size

String inverters are heavier than microinverters. Homeowners frequently install microinverters in smaller houses; they are typically mounted beneath solar panels to conserve space. String inverters require more space than microinverters because they are larger and bulkier, and they must be installed in areas with good ventilation and shade. Customers typically place them in their houses or shaded balcony areas. This takes up a lot of room, but overall, it's a good investment, especially for larger solar systems that need more solar panels connected in series.

Maintenance

String inverters are normally installed on ground level, end-users and installers can easily walk up to the inverter system and swap out the problematic parts with ease. The same can’t be said for microinverters, which are typically mounted below solar panels on the rooftop. End-users and installers would need to climb up to the rooftop to do the maintenance and uninstall the panel on which the microinverter is mounted.

Cost

Subjective. Again, it depends on the size of the solar system in question. Installing string inverters would be cheaper for larger solar systems, as the inverter system cost is shared by more solar panels installed on the rooftop. Conversely, installing microinverters on smaller rooftops, which only have a few solar panels can be cheaper. Ultimately, users need to be aware of the solar sizing of their system to make an informed decision.

Are microinverters better than string inverters?

No system is better than another. It all comes down to individual factors like the size of the system, rooftop orientation, and the energy goals of the user.

Factors to consider when choosing between Microinverters and String Inverters

Size of the solar system

Solar sizing of your system is important when choosing the right solar inverter for your home/business. String inverters are more suitable for larger rooftops which can collect more solar energy. The solar panels can be wired together in a string to process the DC input.

The converse is true; microinverters are more suitable for smaller systems with significantly fewer solar panels - using only a few microinverters to convert DC to AC power for electrical loads.

Rooftop Orientation

Shading and roof orientation affect the amount of solar input received by the solar panels.

Buildings or apartments that face shading conditions on certain orientations would be more suited for a microinverter system. As mentioned previously, the microinverter is a type of MLPE which can optimise the energy efficiency of each solar panel. This means that each microinverter works independently – one panel’s output suffering from shading will not affect the other panels. With a microinverter, the overall solar output will be optimised since shading will not affect the overall solar output of the system. The reverse is true, whereby string inverters are ideal for rooftops with no shading problems, effectively converting all available sunlight into usable power under normal conditions.

A rooftop facing many different directions will also be more suited for a microinverter-based system. The same logic applies to different orientations, whereby the solar output from a shaded portion of the rooftop will not affect the overall output of the entire system. 

Energy Goals

Some homeowners want an upgradeable system, especially when they are still unsure about going solar. Microinverters will be more suitable for such purposes since users can slowly add microinverters to their solar inverter system according to their changing energy goals in the future.

For homeowners who are already aware and confident of the benefits of solar, installing a string inverter saves a lot of time and money, since usually only 1 string inverter is installed to process the large solar inputs by multiple solar panels in the system. The users can enjoy the cost savings brought by the string inverter for a long period until the inverter ages.

Micro inverter or String inverter?

Picking the right inverter can increase your solar system’s performance and maximise your solar savings. There are two main types of inverters to consider: String inverters vs microinverters.

The ideal inverter for you depends on the size of your system, sun exposure, and energy goals.

Learn more about Microinverter and String Inverters here.