Table Of Contents

Inverter Systems

Any solar powering system would be incomplete without its solar inverters. These transform your solar panels' direct current (DC) energy into usable alternating current (AC) electricity for your home's appliances. When choosing an inverter solution for your solar panel installation, there are a number of options to consider. In this article, we'll look at micro inverters, one of the most prominent types of inverter technology available today.

Overview Of Micro Inverters

Instead of a solar energy system with a single centralised string inverter, micro inverters are tiny inverters put directly at the panel location. One micro inverter solar panel system is used for each panel in most micro inverters.

Micro inverters are classed as module-level power electronics since they function at the solar panel site independently of the others in the system (MLPE). For complex installations or those that face minimal shading, MLPEs are the best option.

Want to know more about them? Well, keep reading.

How Do Micro Inverters Work?

The technology used in a typical string inverter is totally different as solar panels can only produce power at the level of the least-performing solar panel on the exact string. This isn't a problem with micro inverters because each solar panel has its own inverter, so even if one solar panel in the system isn't producing electricity, the system will continue to work efficiently.

The size of every micro inverter depends on the size of the solar panel and the quantity of electricity it can produce. Clipping occurs when your solar panel produces more electricity than its micro inverter can convert at any given time, resulting in power losses.

When Should Micro Inverters Be Used?

There are numerous reasons to consider micro inverter installation, and they include:

Checking individual solar panel performance

Micro inverters allow for the monitoring of individual solar panel performance. Instead of measuring the entire system's performance, micro inverters will enable you to examine how each solar panel performs on its own. Because it's easy to recognise if a particular solar panel or micro inverter is failing, this can lead to faster equipment servicing.

During complex solar panel setups

Micro inverters are also excellent for more complex setups with solar panels facing multiple directions or inclined at different angles. If some solar panels face east and some face south, installing micro inverters on each solar panel will enable them to perform to their most significant potential.

This is to say, when sunlight strikes them since they will not be affected by production challenges that other solar panels in the system may encounter.

Pros Of Micro Inverters

Ability to shut down quickly

New electrical rules require speedy solar system shutdown to keep everyone safe from high voltage, for example, when firefighters need to get on rooftops or maintain power lines. These rapid shutdown needs are met by micro inverters, which have this functionality built into each module.

Increased electricity

The main benefit of employing micro inverters is theoretically generating more solar electricity. The primary reason for this is that the currents between solar panels differ slightly. When solar panels are joined in a string formation, the current reduces to that of the string's lowest-producing solar panel.

Suitable for difficult installation situations

As mentioned earlier, micro inverters are the way to go if a solar system faces multiple angles, such as some solar panels facing south, some west, and the rest facing the east. Micro inverters are also ideal if you have shading concerns due to trees or an oversized chimney.

The solar panels will produce fluctuating amounts of electricity at different times in these conditions. Micro inverters will ensure that you harvest all energy, whereas a regular inverter will lose some of it.

High warranty

Micro inverters offer a 25-year warranty, whereas regular inverters have a 10 to 12-year warranty. Although the reliability of micro inverters was questioned a few years ago, that is no longer the case. Technology has since caught up, and the extended warranties now available on micro inverters demonstrate the manufacturers' confidence in their products.

Monitoring at the panel level

Micro inverters and add-on optimisers can track the production of each individual solar panel, whereas traditional inverters can only track the output of the entire system.

Ease of system expansion

Micro inverters are easy to add one at a time if you decide to extend your system in the future. Each solar panel and micro inverter will be easily combined and added to your existing solar battery without any need for brand new string inverters to be bought, sited, and installed.

Roof shading

Many roofs have some form of shade. It may be a shadow cast by a chimney if it isn't trees. Because of the shade, solar panels aren't always as effective as they can be. However, the ability for each solar panel to work independently with micro inverters enables for more energy output and efficiency. Especially when only a few solar panels are in the shade.

Since most roofs have shade, micro inverters are recommended for most home solar panel setups. It's important to mention that some central inverters can be equipped with an optimiser. However, systems using these DC optimisers must meet a particular voltage for the inverter to turn on. Even if half of the system is shaded, the optimiser will not be able to complete its task.

Efficiency

Micro inverters give a 5-15% improvement in production over string inverters since each solar panel can work independently. As mentioned earlier, this is frequently due to their supremacy in cases of shading, but it can also be due to a defective or dirty solar panel.

Furthermore, no two solar panels are the same. Before they leave the manufacturer, average solar energy production can vary by 5% between solar panels. Solar panels, likewise, degrade at various rates over time. The lowest producers always use a string inverter to produce solar energy output, which is always limited. On the other hand, micro inverters allow each solar panel to perform at its full potential.

Cons Of Micro inverters

All good things have their drawbacks, and micro inverters are no different. Here are some of the most common disadvantages of micro inverters:

High cost

Micro inverters are more expensive than other types of inverters. The additional initial investment may be well worth it for the enhanced monitoring and productivity benefits. However, a lower-cost string inverter system can be an excellent alternative if you have a straightforward installation on a single roof plane that faces south with no shade.

The cost of micro inverters is the most significant disadvantage. On average, 5kW house solar installation is around $1000 more expensive than a string inverter.

Maintenance

If one of your micro inverters fails, not only is it challenging to determine which one has gone dead but servicing and replacing the component is not as simple as installing a new string inverter on the south side of your house.

To re-establish AC conversion capabilities, your solar installer needs to get back up on your roof, deal with your racking system, unbolt the solar modules, and replace the micro inverter.

Quantity of hardware on your roof

There will be a lot of pricey metal equipment on your roof, including a micro-inverter attached to each solar panel. Micro inverters have the potential to act as lightning rods in miniature. If you live in a storm-prone area and have a historic timber structure with shake roofing, you may want to reconsider installing micro inverters.

Comparing Micro Inverters And Power Optimisers

Micro inverters and power optimisers are very similar technology, to the point where some businesses refer to them interchangeably. Both are known as 'Module-Level Power Electronics,' or MLPEs, but significant variations may make one more or less suited for your needs.

Similarities

To begin, let's look at how micro inverters and power optimisers are similar:

  • Better functioning of solar panels - Micro inverters and power optimisers assist in better functioning of the solar panels on complex roofs or rooftops with minor shadowing during the day.
  • Offers individual solar panel monitoring - Both power optimisers and micro inverters can offer individual solar panel monitoring, allowing you to compare the number of kilowatt-hours (kWh) produced by each solar panel in your array.
  • One MLPE on the back of each solar panel - Solar businesses often place one MLPE (micro inverter or power optimiser) on the back of each solar panel. So, if your system has 15 solar panels, it's likely that you'll also have 15 micro inverters or power optimisers.

Differences

While micro inverters and power optimisers have a lot in common, they also have a lot of differences, which we'll go over in more detail below:

DC conversion into AC

Micro inverters are devices that convert DC energy into AC energy at the solar panel level. As power optimisers are also found behind solar panels, they do not alter the electricity themselves. Instead, they 'condition' the DC energy before sending it to a central inverter, which completes the conversion. The conditioning process lowers the voltage of the DC energy so that it may be converted to AC energy more efficiently by the centralised inverter.

Warranty

Micro inverters and power optimisers are both covered by a 25-year warranty. While a 25-year warranty covers optimisers, the centralised inverter they are paired with may have a shorter warranty. Installers frequently include an extended warranty on the central inverter in their package deal or charge extra.

It's also crucial to closely examine what's included–and what isn't–in a company's warranty conditions. Is labour for installation, replacement, and delivery of parts covered by the company? And how long does it take exactly to get a warranty claim processed? These factors should be taken into account when deciding which type of inverter to put on your property.

Maintenance

You must examine if and how many times micro inverters and power optimiser systems will fail over their lifetime, as well as the impact of an unlikely failure on the production of your solar panel system. Given the labour required to reach and work on your roof, replacing a micro inverter or a power optimiser on a rooftop will almost certainly cost more than replacing a string inverter on a wall at ground level.

However, that is only part of the calculation regarding long-term maintenance costs. Many string inverters have a 12-year warranty, whereas top micro inverters have a 25-year warranty, suggesting that you may need to replace your inverter halfway through the life of your solar panels.

Battery choices

Battery storage is compatible with both micro inverters and power optimisers. However, you may need to utilise a particular type of inverter depending on whether you want a DC or AC-connected battery solution. Chat to your installer or electrician about which inverters will work best with your battery if you're thinking about getting a battery.

Comparing Micro Inverters And String Inverters

String inverters convert DC to AC at the string level, whereas micro inverters do it at the back of each solar panel present on the roof. Let's look at some of the advantages and disadvantages of each inverter type.

Efficiency

Because of their solar panel optimisation, micro inverters function better for a house with a complicated roof and shading or soiling difficulties. On the other hand, string inverters can do a decent job for houses with a basic roof and good orientation due to their excellent efficiency. Dual MPPT technology is available on the most recent string inverters. The output is improved because the solar inverter may link two imbalanced strings with various orientations.

Initial Price

Micro inverters are more expensive to purchase than string inverters. One of the most common micro inverters costs around $0.7 per watt and comes with a 25-year warranty. String inverters are a third of the price and come with a ten-year warranty.

Maintenance

As they carry little AC voltage, micro inverters have a low individual failure rate. A 5-kW solar powering system, for example, may include 23 micro inverters, and the failure rate rises as the number of elements in the system grows. Someone must climb to the roof, remove solar panels, and install a new micro inverter when one fails. Workers do not need to climb the roof to repair a string inverter because it is mounted on the wall.

Safety

The conversation from DC to AC with individual micro inverters is at the solar panel level. This ensures that your roof's energy remains low-voltage. On the other hand, string inverters combine high-voltage DC and transport them across your roof, increasing the risk of an electrical fire.

Micro Inverter Companies

Micro inverter products are available from a variety of manufacturers; below are a few of the more well-known names:

Enphase

Enphase, a California-based company, is the market leader in micro inverter technology. For home solar panel installations, their IQ series is a popular choice. In addition to producing standalone micro inverters, the company offers AC modules collaborating with several solar panel manufacturers.

In addition to micro inverter products, they also make energy storage and monitoring systems. Enphase micro inverters are certainly one of the best solutions if you're searching for a quality, safe, high-performance solar system with excellent monitoring.

Micros are ideal for roofs with different aspects or shading concerns, especially if each roof segment has a restricted number of solar panels. Micros will offer several advantages and can deliver a better payback throughout the life of the system for commercial systems with many roof pitches, impediments, or where performance monitoring is required.

Enphase micro inverters are among the top micro inverter manufacturers on the market. This is owing to the company's proven track record, low failure rate, high quality, sophisticated system monitoring, and overall excellent service.

The new Enphase energy storage system's heart, the IQ system controller 2, enables grid integration and seamless backup power in the case of a power loss. It effectively allows for the development of a home micro-grid by combining all of the required grid connections equipment into a small, attractive enclosure, making installation much easier and faster.

To allow off-grid capabilities, the controller is required to integrate solar, storage, and even a backup generator. It is only accessible in North America at the moment. The following are the significant features and functions of the IQ System controller:

  • Controls and manages the grid connection.
  • Detects grid outages and switches to backup mode automatically.  
  • Supports both full and partial backups of your house.
  • Split phase 120/240V backup operation with a neutral-forming transformer
  • Compatible (AC) standby generators can be integrated.
  • Compatible with Enphase micro inverters from the IQ8 series and preceding generations.
  • When used in combination with the optional IQ Load Controller, it allows for the priority of electricity to vital loads during a grid outage.

SunPower

In 2014, SunPower, a leading high-efficiency solar panel modules manufacturer, acquired the micro inverter business SolarBridge. However, Sunpower sold their company's micro inverter business to Enphase in 2018. SunPower's AC modules, utilised in their Equinox systems, now feature Enphase micro inverter technology.

APsystems

APsystems was created in 2010 in California. Unlike many other micro inverter systems, their micro inverters are designed to link to several solar panels. One APsystems micro inverter can successfully connect up to four solar panels.

Batteries And Micro Inverters

Unfortunately, you cannot utilise many popular DC battery storage systems in conjunction with tiny inverters. As such, a compatible hybrid string inverter or multi-mode inverter is typically required because most battery systems are DC-linked. Micro inverters cannot be used with these standard DC battery storage systems since they output AC power.

However, they can be used with other popular AC battery systems like the Tesla Powerwall and Sonnen ECO. Enphase Energy makes a 1.2kWh AC battery module that works with the Enphase micro inverter system and may be controlled via the Enphase Enlighten portal.

Because it communicates with the Enphase Envoy, this unique modular system can be expanded as needed. It also enables a full range of load shifting and demand management features. The Enphase AC battery's only drawback is that it cannot be utilised as a backup power supply at this time. Fortunately, numerous popular AC batteries, such as the Tesla Powerwall 2 and the new Enphase Empower solar batteries, now offer backup functionality.

Get Your Micro Inverter

Enphase micro inverters and AC modules offer numerous advantages when individual panel-level monitoring is required. Micro inverters have a higher upfront cost for smaller systems than string inverter systems, and the price differential grows significantly for more extensive systems.

A decent-quality string inverter will be more economical if you have a tight budget and large open roof areas with no shading difficulties. Micro inverters were not previously considered a viable alternative for energy storage.

This has suddenly changed with the powerful new Enphase IQ energy storage system and smart controllers built for seamless integration of solar panels, solar batteries, and even backup solar generators to enable partial and complete off-grid operation.

Solar Power System Monitoring

If you have been thinking of getting a micro inverter, it's a good idea to first contact reputable professional solar installers to better guide you on what options will be best suited for your specific needs. However, remember, a string inverter may still be suitable for your needs depending on your situation, so don't rush to get a micro inverter without consulting a solar installer that has a good understanding of these products.