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Advantages & disadvantages of micro-inverters & power optimizers

Last updated 2/28/2019

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Centralized string inverters are still the most common technology option for rooftop solar panel systems in the United States. However, thanks the advantages that micro-inverters and power optimizers (often referred to as module-level power electronics, or MLPEs) offer, they are quickly gaining popularity. But are micro-inverters or power optimizers right for you and your solar panel system?

Micro-inverters and power optimizers offer similar benefits but operate in different ways. Both are mounted next to individual solar panels and prevent performance issues if one or more of your solar panels are shaded. The key difference is that micro-inverters convert the DC electricity generated by your solar panels into the AC electricity that your household appliances use, while optimizers “condition” the DC electricity before sending it to a central inverter.

Key takeaways: String inverters vs. Micro-inverters vs. Power optimizers
  • String inverters are generally the most affordable inverter option and function best when your roof is ideal for solar.
  • Micro-inverters and power optimizers are best suited for roofs that have shading or are oriented in multiple directions.
  • Because micro-inverters and power optimizers are more efficient than string inverters, a system that uses them will produce slightly more power than a similar system with a string inverter.
  • Because there are more electronic components, micro-inverters and power optimizers may require additional effort to repair. However, if a malfunction does occur, the loss is isolated to a single panel and does not cause the entire system to stop producing power.
  • If you are considering getting a solar power system with micro-inverters or power optimizers, pay careful attention to whether the additional cost is worth it to you.
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Advantages of micro-inverters & power optimizers

MLPE technologies offer the following advantages over centralized string inverters:

  • If one of the solar panels in a system is underperforming, MLPE devices ensure that your system still produces a substantial amount of power. With a central string inverter, overall system power generation can fall sharply if a single panel stops producing power. With MLPE systems, if one panel fails, the others will still continue to produce electricity.
  • They are a good option for “complicated” roofs that face multiple directions. With string inverters, panels in the same string must have the same orientation so that each one has the same power output. Otherwise, overall solar power production can drop significantly, because one panel producing less power will reduce output for the entire string.
  • They allow you to monitor the performance of individual solar panels, usually through a smartphone app or web portal. This makes for quick identification of problems and easy troubleshooting.
  • They convert DC power to AC power more efficiently than string inverters, and help to maximize total solar system power production. This means more power produced with the same number of panels.
  • They typically come with longer warranties than string inverters – up to 25 years when they are integrated with solar panels. String inverters are usually warrantied for 10 years and will typically remain operational for about 15 years before needing to be replaced.

Remember that, although micro-inverters and power optimizers are more efficient, they are not always a better investment. If you pay significantly more to get a system with micro-inverters or optimizers, you can get more power out of your panels, but it won’t always translate into a greater return on investment or shorter payback period. Get an instant estimate of solar savingswith EnergySage’s Solar Calculator, or register your property to get solar installation quotes from qualified installers at no cost.

Disadvantages of micro-inverters & power optimizers

The potential disadvantages of micro-inverters and power optimizers have to do with maintenance and reliability, rather than how well the devices convert DC electricity to AC.

  • MLPE technologies have higher costs when compared to string inverters, because more pieces of equipment must be used.
  • More equipment may mean higher likelihood of breakdowns. While string inverters may not deal with shading as well as MLPE technologies, the upside is that a system with a string inverter contains fewer pieces of high-tech equipment.
  • MLPE devices do their work in a relatively harsh environment. Your roof is exposed to the elements year-round. With micro-inverter and power optimizer systems, all or most of the critical equipment sits on the roof through rain, snow and heat. By comparison, string inverters are generally located off of the roof.
  • Maintenance and replacement may require more effort. In the event of a problem, a technician will need to access the roof to make repairs. Depending on your maintenance plan and warranty, this may cost you money.

Micro-inverters and power optimizers are a premium product, but they come at a premium price. Spending the additional money for micro-inverters or power optimizers isn’t always necessary. They are the best option where partial shading or a complicated roof would negatively impact solar system performance. If you have an uncomplicated, unshaded roof, a string inverter can be a better value.

You should always shop around and compare the cost and savings associated with various equipment options and their cost and savings. Register your property on the EnergySage Solar Marketplace today to receive solar quotes from multiple pre-screened solar installers near you.

Comparison table: String inverters, micro-inverters & power optimizers

  String inverters Micro-inverters & power optimizers
Cost Lowest Highest
Efficiency Lower High
Warranty 5-10 years 25 years (panel-integrated)
Performance when some panels are shaded Poor Good
Performance on "complicated" roofs Poor Good
Amount of electronics on roof Least Medium - Most
Performance with "complicated" solar panel arrays Low High
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