5 Tips for Choosing a Microinverter 0

 As concerns over the environment and economy grow, more people are choosing sustainable energy options. The high cost of installation and maintenance had initially restrained the market growth of solar panels that were connected together in series to create higher voltage DC, but microinverters have emerged as a more accessible option. 

In fact, our previous article highlighted how large-scale PV plants in the US generated 63 billion kilowatt-hours of power in 2018. The total number of solar installations is only going to double in the next five years for residential and commercial use, so it’s clear that solar energy is becoming the norm. 

What is a Microinverter?

Microinverters are strategically sized to suit individual solar panels rather than a string of solar modules. An introduction to microinverters by Hoymiles explains how converting energy into safe electricity also tends to create waste that is unusable. It is therefore important to ensure that the microinverter has a high Maximum Power Point Tracking (MPPT) efficiency rating to maximize productivity.  

Things to consider when choosing a microinverter

Not all micro inverters were created equal, however. Here are our tips on what to look out for when selecting a microinverter. 

  • Input Voltage
  • Energy Efficiency
  • Size & Weight
  • Available Warranty
  • Peak Output Power

Input Voltage

Microinverters come in different sizes, each designed to handle different voltages of electricity. It is important to select the right voltage according to the power of the inverter lest we risk potential danger, as an increase in the output power increases input currents and vice-versa.  

AAC’s guide to key issues on power supplies explains that input undervoltage and overvoltage are among the most common, yet problematic, issues. Sustained input overvoltages can lead to damage to the unit, while undervoltage can cause problems with output regulation and control, resulting in increased input current and power dissipation.

For starters, remember the following for microinverters: 12 V at a power up to 600 W; 24 V at a power from 600 to 1500 W; and 48 V at a power of more than 1500 W. 

Energy Efficiency

 Microinverters have varying efficiencies just like solar panels. As the earlier Hoymiles’ guide explains, efficiency measures how much energy is lost in the form of heat during the conversion from DC to AC electricity. A high Maximum Power Point Tracking (MPPT) efficiency leads to a higher overall system efficiency and more solar electricity production.

This is usually expressed in terms of a curve, and can be compared on various manufacturer websites and resources. A good efficiency curve should reflect consistent performance and (1) create curves that rise quickly; (2) create flat curves with no dropping phenomenon; (3) offer high performance under full load; and (4) show overlapping curves at different voltages.

Size & Weight

 For regular-sized inverters, Interior recommends oversizing by 10-20% as a good rule of thumb to minimize costs while maximizing production. With microinverters, while varying sizes do still exist, their primary significance would be their aforementioned ability to handle different voltages. Microinverters’ small size is a defining feature for easier installation, after all. 

Microinverters are usually around 200–250 W in size. Larger microinverters will likely be more expensive, but a microinverter that is too small for the associated panel’s energy output will result in too much clipping and wasted energy. Guidelines on the maximum DC wattage per panel will be listed by the manufacturers. 

Available Warranty

 Most microinverter options on the market today come with a 25-year warranty. This makes for a pretty good deal, as PV Magazine’s article on lifespans claims that microinverters have a service life of 25 years — nearly as long as their panel counterparts and much longer than string inverters that last about 10 to 15 years.  

However, many factors such as heat, humidity, and regular maintenance can directly affect microinverters’ overall lifespan. Warranty will protect you against any manufacturing defects or undue degradation, depending on their level of coverage. Make sure to read and compare warranty agreements when choosing solar equipment.

 Peak Output Power

 Peak power is the maximum electric power that can be produced. These values can be found in the products’ datasheets and are provided by manufacturers based on STC (Standard Testing Conditions). A high peak AC power output means that the inverting device is able to handle and feed into the grid a larger amount of power produced by the solar panels.

As more options for sustainability are made readily available for various consumers, our craving for energy independence attains a higher standard. It’s thus no wonder that an increasing number of homes and multinational companies are investing in solar energy.

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