Solar Inverters: Types, Pros and Cons

What is a solar inverter?

Solar energy doesn’t provide electricity in a format that your table lamp could be powered by. Inverters change the power produced by your solar panels into something you can actually use.

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Think of it as a currency exchange for your power. You might have a fistful of yen, but until you stop and exchange it for USD, you can’t pay for lunch stateside.

Your home is wired to conduct alternating current (AC) power. The electricity produced by solar panels is initially a direct current (DC). Inverters change the raw DC power into AC power so your lamp can use it to light up the room.

Inverters are incredibly important pieces of equipment in a rooftop solar system. There are three options available: string inverters, microinverters, and power optimizers.

Did you know? With the “One Big Beautiful Bill” signed into law, the 30% tax credit for residential solar is going away at the end of . Homeowners will need to get their systems installed by December 31, to qualify for this credit before it is gone. Start your project with multiple quotes from trusted local installers today.

See our list of the best inverters of .

Solar Inverter Types, Pros and Cons

String Inverters

String inverters have one centralized inverter — or, keeping with the metaphor — one central currency exchange station.

This is a standard inverter, and it works just fine if you don’t have any encroaching shade from nearby trees or a big chimney. It’s also great if you have all of your solar panels facing the same direction.

String inverters are standard in the industry, and they’re the least expensive.

String inverter pros:

• Lowest cost
• Standard inverter
• Performs well with no shade

String inverter cons:

• Overall production decreases if one panel is damaged or shaded
• No ability to monitor each panel individually
• Not optimal if your solar panels are facing different ways
• Increasing power needs are more difficult and may require second central inverter installation

Microinverters

Microinverters are small units built into each individual solar panel that convert power. Think of it as having mini currency exchange stations on every nearby street corner.

This gives each panel the ability to function at peak performance, independent from its neighbors. Even if the panel next to it has a tree branch shading it for most of the day, all the other panels can convert at full capacity. Any drop in efficiency only affects one panel.

Microinverters also enable you to monitor the performance of each individual panel. This is helpful for spotting any issues with a single panel so you can have it repaired before it slows down the whole system’s productivity.

This type of inverter can be more expensive than string inverters, but it can pay off over time by getting more power from your system overall.

Microinverters also make it easy to increase power usage if you want to. Say you buy an electric car and you’ll need more power to charge it every night. Adding more solar panels and inverters is easier and less expensive than adding an additional central inverter for a string inverter system.

Read more about string inverters vs microinverters here.

Microinverter pros:

• Shade from a nearby tree won’t reduce the whole solar panel system power output
• Individual panel monitoring available
• Increasing power needs are easier and less expensive than installing a second central inverter
• Good for rooftops where solar panels may face different directions

Microinverter cons:

• Higher initial cost
• Not necessary if all panels face the same way and are not shaded

Power Optimizers

Power optimizers are somewhere in between string inverters and micro-inverters both in how they function and in price.

As with micro-inverters, power optimizers have a component (the “optimizer”) underneath and within each solar panel. But rather than change the DC to AC right there on site, these inverters optimize the current before sending it to one central inverter.

This is more efficient than a string inverter, as any sluggish production from one panel doesn’t slow the whole system, but more cost-efficient than a standard micro-inverter setup.

Imagine being able to cut to the front of the line at the currency exchange office. It’s not quite as quick or convenient as having your own exchange office a few steps from your home, but there’s no waiting around once you get to the central office.

Micro-inverters and power optimizers are gaining popularity and prices are dropping as the technology advances.

We have more details on power optimizers in this post.

Power optimizer pros:

• More efficient than string inverters
• Less expensive than micro-inverters
• Individual panel monitoring available

Power optimizer cons:

• Higher initial cost
• Not necessary if all panels face the same way and are not shaded

Ultimately, best inverter for you depends on your roof shape and size, nearby trees, how much energy you need, and your budget.

What to Look for in a Solar Inverter

To recap, there are three kinds of inverters: string inverters, microinverters, and power optimizers.

They all transform the power your solar panels generate from direct current (DC) to alternating current (AC). This makes the energy usable for your home.

Here’s a few things to look for when shopping for inverters…

Solar Inverter Warranties

Most people feel more comfortable purchasing electronic devices with warranties. Solar inverters are no exception. Most inverters have warranties ranging from anywhere between 5 and 10 years, though some can be extended to 25 years.

When you’re looking at a company, make sure you know what’s included in the warranty and what’s not. For example, some power optimizers might not include the central inverter under the warranty.

Also make sure you understand the terms of a warranty. Is the device covered in case of an internal glitch as well as in the case of external damage? Will you be charged for labor or shipping if you have to send parts in? These are all important questions to ask.

Solar Inverter Operating Temperatures

As with most electronic equipment, inverters operate best when they’re running cool. Operating temperature is the safest temperature range an inverter maintains.

Inverters will naturally generate some heat themselves as they do their job. Since they’re typically in an uncontrollable environment outdoors, they’re exposed to a wide range of temperature fluctuations.

Obviously, conditions aren’t always ideal and some times an inverter will have to work harder than others. The higher the operating temperature (the more heat it can handle), the better.

Solar Inverter Efficiency

There are two numbers to look for in solar inverter efficiency: peak efficiency and weighted efficiency.

Peak efficiency will give you the efficiency of your inverter when it’s running optimally. It’s good to know what the best-case scenario is, but it’s also worth noting that it won’t always be hitting that level. Some days it might only reach peak efficiency for an hour or two, or maybe not at all.

Weighted efficiency figures in the variables like DC input levels. This gives a more accurate gauge as sunshine, temperature, and other environmental elements affect inverter efficiency throughout the day.

Are you interested in learning more about residential inverter? Contact us today to secure an expert consultation!

Solar Inverter Key Terms to Know

Clipping/Scalping

This is the term used to describe the energy output that is lost due to undersizing an inverter.

Any given inverter has a maximum power rating (at the residential level, measured in W or kW). When solar supplies DC power in excess of that inverter’s maximum power rating (what the inverter can handle), the resulting power is “clipped.” Think of it like a 14 foot tall truck trying to go under a 13 foot bridge — a little comes off the top.

It’s important to consider the solar panel arrays’ maximum power output and select an inverter with the correct size, model, and type in order to avoid excessive clipping.

It’s normal for the DC system size to be about 1.2x greater than the inverter system’s max AC power rating. For example, a 12 kW solar PV array paired with a 10 kW inverter is said to have a DC:AC ratio — or “Inverter Load Ratio” — of 1.2.

When you into account real-world, site-specific conditions that affect power output, it may make sense to size the solar array a bit larger than the inverter’s max power rating, as there may be very few “power-limiting days,” or instances of clipping for that system.

Inverter Efficiency

Inverter efficiency is a percentage that tells us how much DC power input to an inverter comes out as usable AC power.

No inverter is 100% efficient, although some come close in favorable conditions. In the conversion from DC to AC, power is lost in the form of heat.

While inverter efficiency is an important factor to consider in the selection process, there are other factors to consider that also affect a project’s economics, such as warranty, price, expected life, serviceability, and monitoring functions.

Maximum Power

Maximum power is the highest amount of power allowed to feed into an inverter, which is a function of the inverter’s specifications or the maximum power a solar panel can produce. This will occur at the optimal trade-off between voltage and current along a given panel’s I-V (current and voltage) curve.

Maximum Power Point (MPP)

A solar system’s maximum power output will vary with conditions, such as how much sunlight it receives, temperature, and other factors. A fixed-tilt, stationary, roof or ground-mounted solar PV system might only produce its maximum rated power during a limited period of the day. Every specific solar cell has its own unique I-V curve, which relates its maximum power output to variations in current (I) and voltage (V).

Maximum Power Point Tracker (MPPT)

A device that periodically tracks characteristics of a given panel, string of panels, or system, and optimizes and varies voltage and amperage accordingly in order to produce maximum power.

Microinverter

A device that converts direct current (DC) produced by a single solar panel into alternating current (AC).

Micro-inverters are commonly connected to and installed at the site of, or behind, each individual solar panel in an array. Most micro-inverter makes are installed in the field, while some come panel-integrated by the manufacturer.

Popular brands of micro-inverters include: Enphase, Chilicon, APS, ABB, SMA, and SunPower.

Optimizer

A DC-DC converter, optimizer, or “panel optimizer,” is a module-level power electronic device that increases the solar system’s energy output by constantly measuring the MPPT of each individual panel.

The panel optimizers relay performance characteristics via a monitoring system to facilitate operations and any necessary maintenance. In essence, optimizers support flexible system designs and arrangements – with multiple panel orientations, tilts, azimuths, and module types in a given string.

Because optimizers are a DC-DC, or DC-coupled, systems using this technology will generally be compatible with DC-coupled energy storage or battery backup solutions, like the Tesla Powerwall.

Perhaps the most advantageous benefit of using a DC optimizer is panel-level MPPT, or max-power point tracking. The result is increased energy harvest from a panel system, especially when subject to periodic or sweeping shade.

Peak Power Point

Another term for Maximum Power Point (MPP).

String Inverter

The device that converts direct current (DC) electricity produced by groups of solar panels (called strings), into usable alternating current (AC) electricity.

String inverters are considered a “mature” solar technology that has proved effective, safe, and reliable. Residential, 240V AC string inverters usually carry manufacturers’ warranties of about 10 years.

When installed to a manufacturer’s specifications, code, and best practices, a string inverter may require service or ultimately replacement during a photovoltaic system’s lifespan.

Solar Inverters Explained!

A solar inverter is a component of your solar energy system that’s responsible for converting the solar energy that your PV panels capture into usable electricity. Every solar energy system has one or multiple solar power inverters, and your solar panels couldn’t function without one!  

But how do solar inverters work exactly? And what is the best solar inverter for your solar energy system? Keep reading for answers to these and more questions about solar inverters, from the experts at Boston Solar. We’re the number one Massachusetts-based solar energy company, and we’ve installed more than 4,800 solar panel systems. 

What Are Solar Inverters & How Do They Work? 

A solar inverter is an electrical device that’s connected to your solar energy system. Its main purpose is to convert direct current (DC) electricity into alternating current (AC) electricity. This is necessary because the electricity that solar panels generate is not the same type of electricity that we use to power our homes. 

Solar PV panels produce an electrical current called direct current (DC) electricity. However, the electric grid (and all the homes and buildings connected to it) use alternating current (AC) electricity, which means your solar system needs to convert the energy it captures into usable, AC electricity before it can be sent to your home or business. This job falls to the solar inverter. The DC electricity that’s generated by your solar panels is sent to your inverter, which converts it into AC electricity. Energy that’s stored in your solar batteries is also sent to your inverter before it can be used by your home. 

AC vs. DC electricity 

To provide a more technical explanation, we need to dive a little bit deeper into the behaviors of AC and DC electricity. DC electricity moves in one direction and maintains a constant voltage. AC electricity can change from positive to negative voltage and switches direction as it does so. To convert DC electricity into AC electricity, an inverter switches the flow of the DC input back and forth rapidly. This causes the DC electricity to behave like AC electricity and effectively transforms it. 

But DC to AC conversion isn’t your solar panel inverter’s only function. Solar inverters also play a role in system monitoring and allow your solar energy system to communicate with computer networks. 

Are There Different Types of Solar Inverters? 

There are a few different types of solar inverters, the most common being string inverters and microinverters. 

How Do String Inverters Work? 

A string inverter connects to a set—or string—of solar panels and converts the electricity that’s generated by the entire string of panels. String inverters are cost-effective, but they have some downsides. If there is an issue with a single panel connected to a string inverter, such as shading or damage, the entire string is affected and power production is reduced.

How Do Microinverters Work?  

Microinverters are a newer technology that’s quickly gaining popularity, especially in residential solar applications. Microinverters are small devices attached to individual panels. They convert power from each panel separately instead of sending it to one central inverter. This separation prevents issues with one panel from disrupting the entire system and allows each panel to be monitored individually. 

Enphase Inverters for Maximum Energy Output

Here at Boston Solar, we install industry leading solar panels and products, which is why we primarily use Enphase inverters. These powerful microinverters maximize power from every panel and allow you to generate power constantly, even if one microinverter fails. 

Enphase inverters are designed to withstand severe weather conditions and are recommended by the Federal Emergency Management Agency (FEMA). Plus, thanks to their modular design, Enphase microinverters make it easy to expand your solar array as your power needs grow and change. 

The company is the world’s best commercial inverters supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.