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The article discusses micro inverters as an alternative to standard string inverters for solar power systems. Micro inverters offer advantages such as better performance in challenging conditions like shade and different panel orientations. They work by being installed under each solar panel in a system, unlike string inverters which are typically installed for the entire system. Micro inverters allow each solar panel to perform at its best by converting the power they generate to the grid voltage. They comply with modern electrical codes and have rapid shutdown capabilities for safety. Additionally, micro inverters have a 25-year warranty, monitor each panel's production level individually, and make it easier to expand a solar system.

However, micro inverters are more expensive than string inverters, and detecting and replacing a failed micro inverter can be challenging. They are also exposed to the elements and can potentially become lightning rods. Despite these drawbacks, micro inverters are considered a long-term investment with benefits like higher electricity yield and easier installation for complex situations.

Introduction

Micro inverters offer an alternative to the standard string series inverter. The advantages of a micro-inverter will have you reaping the rewards down the road, especially if you’re having trouble with your solar system’s orientation and shade. 

There’s more to them, too, and we’ll be looking at each facet that comes with a micro inverter to give you all the information you need to make the best choices.

What Is a Micro Inverter?

A micro inverter controls the same essential function as a string inverter does. One small difference is that a micro inverter is installed under every solar panel in your solar power system. 

While you’d typically have one solar panel inverter for your solar system a micro inverter system needs the same number of micro inverters as there are panels. However, there are some micro inverters that can accommodate two or even four panels at a time. 

Standard string inverters generally cap the electrical output of solar PV systems according to the lowest producing panel. Micro inverters avoid this dilemma because they work in a parallel circuit, unlike the string inverter which works in a series circuit.

Micro inverters allow each solar panel to perform at its best and contribute as much electrical power as possible. A micro inverter takes full advantage of each solar panel, converting the power they generate to the grid voltage. 

Pros

In recent years, new electrical codes have been introduced that require solar systems to come installed with a rapid shutdown capability to keep first responders and firefighters safe from high voltages. Micro inverters comply with these codes and each module has this particular capability built into them.

A big advantage of micro inverters is that they can potentially yield more electricity from your solar system because of their parallel circuitry. This is because of the slight differences in electrical currents between the multiple solar panels that make up a larger system. 

A micro inverter can work around challenging installation circumstances. 

For example, let’s say you have multiple solar panels facing different directions or some that may be under more shade than others. Micro inverters are able to harvest all of the energy, even if some panels’ performance varies throughout the day.

Standard inverters have warranties that guarantee 8 to 12 years of service. A typical micro inverter has a 25-year warranty. The technology used for these inverters has caught up with the industry, instilling a significant amount of confidence in the manufacturers of these products. 

Micro inverters monitor each panel’s individual production level, allowing you to see which panels are making the most energy for your system and which ones may need to be moved or replaced. 

Expanding your solar system is also easier when using micro inverters. They’re a breeze to install without the need to purchase, site, or install additional string inverters. 

Cons

One of the most apparent disadvantages of micro inverters is their price tag, which is about $1,000 more than a typical string inverter. Well, why would you opt for a micro inverter now, right? While it is pricier, we like to think of it as an investment with benefits in the long run. 

In a solar system with multiple micro inverters, it can be challenging to detect if one fails. Not only that, but replacing the component isn’t any easier. An installer needs to work with the racking system, unscrew a few modules, and then replace the micro inverter. 

Having multiple micro inverters installed on your roof means that there’s a bunch of metal equipment exposed to the elements. The drawback is that each micro inverter has the potential to become a small lightning rod. 

This makes it risky for wooden homes to have them installed. There is a way around this, however. If you still think that micro inverters are the way to go, we recommend looking at installing a ground mount solar system. 

Micro Inverters vs String Inverters

The inverter is the most complex electronic device you’ll find in a solar system but it’s also one of the more common components to fail. Micro inverters are best suited for circumstances where too much shade is a recurring issue, and a string inverter works only when there’s no shade at all. 

While micro inverters can monitor each panel individually, most manufacturers don’t include the monitoring equipment you need to attach to each micro inverter. Only the installer is capable of viewing panel-level data unless you buy the higher level of marketing as an “upgrade.” 

This means that you, as the customer, are only ever able to see feedback from the entire system, which can make it difficult to spot whether each individual panel is performing at its highest. However, when a string inverter fails the entire system goes out with it. 

Pros

When a series string solar system produces High Voltage DC, it runs the risk of high temperature arcing and potentially causing a fire. The risk is greatly minimized once a micro inverter is installed since they convert electrical output up to 240V AC.

Without a micro inverter, your solar panels only put out electrical power in DC. Another way of converting that power would be by installing a solar system generator so that your home can use the electricity generated by the panels. 

AC solar panels are often equipped with an instrument called a ‘switchgear,’ which primarily functions to protect, control, and isolate electrical equipment from things like static and ambient electricity and lightning bolts. 

All solar panels have slight differences in their electrical characteristics because of the manufacturing process. Connecting these solar panels in series results in a mismatch between factors like the voltage, current, and resistance. Micro inverters adapt to each solar panel’s individual characteristics, which avoids solar panel mismatch and improves the overall efficiency of the system. 

Similar to mismatch, solar panels can also have different Maximum Power Points (MPP). This is the point where maximum power can be gained from a solar panel. A micro inverter can target this particular point much better because it’s attached to each individual panel. 

Having components assembled and connected in a factory saves you time and money, most importantly the parts are assembled in a controlled environment. Most manufacturers nowadays assemble micro inverters in their factories to make AC solar panels. 

String inverters can’t be modulated as much as a micro inverter can. A series inverter is limited to a specific number of panels while an AC solar panel can work independently of another.

When connected to a series string inverter, all of your solar panels need to be in the same orientation to put out the same voltage simultaneously and get the inverter started. Since AC solar panels can work on their own, they can be orientated in any direction and won’t have an effect on other panels. 

Cons

Since micro inverters are attached to the solar panels on your roof, it needs someone to get up there and disconnect the micro inverter if there’s ever a fault that causes the system to go down. This can add up to labor and time costs, where a series string inverter can simply be taken off the wall. 

Micro inverters are more exposed to different kinds of weather including rain, snow, and warm temperatures. In general, extreme weather can reduce an electronic device’s efficiency and life expectancy. 

In cases like that, it’s probably better to install a backup solar generator for your solar system, as it kicks in whenever there’s no power flowing directly to your home so you still have lights in the event of an emergency.

While micro inverters have come a long way in the last decade, they’re still not as close to the efficiency levels that series string inverters are currently capable of. Make sure to check out the efficiency rating of a micro inverter system before you purchase one for your home.

Micro Inverters & AC Solar Panels

When solar panels were just starting out, they produced electricity in Direct Current or DC. Being able to use that electricity meant that it had to be converted to Alternating Current or AC by using an inverter, since this is the modulation that’s used by appliances in our homes.

In solar systems that are connected to the grid, the solar panels had to be connected together in series, also called strings, to make higher outputs in DC. Doing so reduced losses but created other issues as a result. 

Micro inverters are made to be small to suit an individual solar panel instead of using a string of solar modules. A solar panel that has a micro inverter built into it is referred to as an AC panel since it’s producing Alternating Current and not Direct Current.

More people are willing to pay a premium for micro inverters, since they avoid mismatching, are modular, and work to maintain optimal efficiency levels. If you’re having issues with shading and orientation, micro inverters are your ideal choice.

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