What are microinverters?
In this article, we’ll introduce you to microinverters. They can be a compelling way to convert the direct current (DC) from your solar panels to the alternating current (AC) your home uses, especially if you have shading considerations to account for, or multiple roof angles to install on.
There are several advantages and disadvantages to be aware of, and we’ll cover them all below.
In this blog:
- How do microinverters work?
- Advantages of microinverters
- 25-year warranty
- Easy to install
- Performance monitoring
- Optimal performance in shade
- Easy system expansion
- Disadvantages of microinverters
- Final thoughts
How do microinverters work?
“Micro” means small. If you were ordering french fries, the micro size might be four or five small fries in a miniature bag. Applying the term “micro” to renewable energy and your rooftop photovoltaic system - micro inverters are very small solar inverters.
Solar inverters convert the direct current (DC) from your solar panels into alternating current (AC) your home appliances use.
In regular string inverter systems, solar modules are simply wired together and fed along down to a single inverter. In this configuration, solar energy output depends on the performance of the worst-performing panel, since they are all grouped in a set.
However, microinverters are designed to be placed behind every single panel in your solar array instead of next to your fuse box. Enphase Energy was the pioneer behind solar microinverter technology. They have been manufacturing these small inverters for solar power systems since 2008.
Microinverters capture all the available electricity from each individual solar panel, convert it onsite to AC, and then send it along to your fuse box and electric grid. This makes your solar panel system more efficient, since even if a few of your panels have shading issues, your total output won’t suffer.
If you need help, or would like to estimate the solar potential for your roof, connect with our network of solar installers to offer guidance and provide you custom savings estimates.
Advantages of microinverter systems
Microinverters have a few notable advantages over other solar power inverter systems, here are some of them to consider:
Microinverters have a 25-year warranty
Longevity is an important consideration. The inverter is the most expensive component of your solar system, and the most likely to fail. It’s heartening to know microinverters have warranties that last as long as your solar panels do - 25 years. Other inverter technology like string and hybrid inverters have warranties that last just 8 to 12 years.
Panel-integrated microinverters are easy to install
Solar panel manufacturers like LG are integrating microinverters into their panels out of the box to make installation easier for installers. All that needs to be done is wiring the panels to one another and the system is ready to go.
This can significantly cut down on your installation costs, since labor hours are a sizable part of your investment.
Since microinverters are placed behind every panel in your PV system, you can track individual panel performance using your smartphone. Smart applications like the Enphase Enlighten system can notify you when your electricity performance is less than expected.
For example, if the current weather is clear and sunny, and your panels are performing as if it were a cloudy day, you’ll get notification that your panels are not producing in their normal range. In this way, you can check for possible debris, bird poop, or equipment damage which may be impacting your system’s performance.
Optimal performance in partial shade and different roof angles
Even if some of your solar panels are shaded during the morning or evening, microinverters ensure maximum AC electricity flows to your fuse box and electric grid. This is because microinverters make it so each panel’s production capacity does not need to rely on the performance of a neighboring panel.
This feature is also useful for complex roof types with multiple angles. If a few panels point toward the sun at a slightly less efficient angle, the rest of your system will still be cranking out watts at peak levels.
System expansion is a breeze
With microinverters, your solar system can be easily expanded in the future. This can be helpful if you have a limited budget right now and know at some point down the road you’d like to harvest more energy. Perhaps you know you’ll be using more energy at a later date because you’re working on a brood of a family or have dreams of a home-based workshop.
Since the DC to AC conversion occurs at the site of each panel, your system doesn’t need to be paired to the capacity of a central inverter. Your solar installer can simply splice in more panels to your system.
Disadvantages of microinverters
Listed below are some issues to take into account with microinverters, because not one type of inverter is going to check all the boxes (unfortunately).
Microinverters cost more than other inverters
Microinverters are relatively expensive. They need to be affixed to the back of every single solar panel. They typically cost $1,000 or more than a string inverter on a standard 5kW residential solar installation.
Unless using a panel integrated microinverter such as the LG model mentioned above, installer labor hours are going to make up the majority of the installation cost difference between using a string inverter or microinverters. That amount can vary quite a bit depending on the installer you use, and how challenging your roof is to work on.
Panel-level performance monitoring may not be available without an upgrade
Although microinverter manufacturers sell the ability to monitor each panel, they do not always include the actual monitoring that allows you to have the same performance visibility your installer does, unless you buy an upgrade.
The reason they may do this is to protect themselves and their installers from support calls related to broken microinverters. It is very difficult to determine if only one or two microinverters out of 25 or so have failed without panel-level analysis, instead of system-wide monitoring that is commonly offered instead.
Most microinverter manufacturers claim very low failure rates but at SolarReviews, we remain skeptical of these claims. The most complex electronics in solar systems are the inverters, and it’s the most common thing to fail in a solar setup.
We would be very reluctant to put 20 microinverters up on a job rather than installing one string inverter, unless there were severe shading or roof complexity issues to overcome. For example, if you’ve got trees which regularly impede your installation’s access to the afternoon sun, or you have limited roof area and need to install on a west facing side in addition to south, microinverters would still be a sensible option.
Less suitability for battery backup systems
If you’re looking to add battery storage to your solar system, microinverters are not the best choice. For maximum power output, it’d make more sense to couple your panels to your battery before converting the electricity to AC and then back to DC again.
Since batteries operate in DC, and your panels generate DC, we recommend using DC power optimizers or hybrid inverters instead. They pair with DC batteries for more efficiency.
Hybrid inverters come with integrated charge controllers, while microinverters do not have this function. SolarEdge specializes in DC power optimizer systems.
More technology on your roof
Microinverters are meant to be installed behind every solar panel on your roof - that’s a lot of electrical equipment overhead. If you have an older home with more exposed wood beams, we’d be concerned about the possibility of each microinverter becoming a lightning rod.
Enphase, the leading manufacturer of microinverters, has responded to the question of whether microinverters can be damaged by lightning. While they say their devices have surge protection that is greater than string inverters, they say in the same breath that you may be required to install additional lightning protection due to local standards. They do not comment on the increased chances your roof will be struck by lightning, however.
We’d have to imagine there are added risks associated with having this much greater amount of wiring and DC power switching up on your roof. This risk should be at least considered before proceeding.
Final thoughts on microinverters
For challenging solar installation considerations, microinverters provide an elegant solution to maximize the energy produced by all of your panels, and convert it onsite to AC electricity. They free up wall space by making a separate inverter no longer necessary.
So, if you have limited roof space with multiple angles, have shading from trees or a chimney to contend with, and you are unsure if you may want to increase the size of your solar system at some point, microinverters can be an excellent inverter choice.
However, microinverters are not ideal in terms of their added cost, and decreased efficiency for energy storage systems. There’s also the issue of having all that metal equipment up on your rooftop, which may be enticing for lightning to hit.
We recommend you consider using DC power optimizers instead of microinverters, particularly if you’re interested in home battery backup. Refer to our guide which helps you to choose the best inverter system for your home.
Author: Dan Hahn | Solar Journalist
Dan is a solar journalist and content advisor with SolarReviews. He also works with solar installers and solar nonprofits to develop and execute strategic plans.