If you’re thinking about going solar, you may want to research what the best solar panel is, but in my opinion, it’s even more important to choose the right inverter. While there are subtle advantages and disadvantages to different solar panels, bad inverters are the biggest cause of problems with solar systems. Having the right inverter can make a huge difference in the long-term performance of a solar system.
Inverters take DC energy from the solar panels and convert it into AC electricity that your home can use. It’s often the most complicated piece of equipment in a solar system and usually the second most expensive, after the panels themselves. They are also the most likely piece of equipment to cause a major loss of production if they fail.
There are a lot of technical specs that can be dug into with inverters, like CEC efficiency, power input & output, and more, but from installing solar for over a decade, the part that matters most to me is reliability.
Are Microinverters Better Than String Inverters?
There are essentially two types of inverters on the market: string inverters and microinverters. Which one is better depends on the site and the system design. In general, we recommend string inverters for ground-mounted systems, mainly due to current code requirements. Certain brands of string inverters, like SMA and Fronius, can be extremely reliable and offer performance comparable to microinverters. Here are some general rules about when a particular inverter is best:
Microinverters are best for:
- Rooftop installations
- Sites with shading considerations
- Multiple different roof orientations
String inverters are best for:
- Ground mounts
- Sites with no shading
- Carports / open barns
Due to changes in the electric code, most string inverters cannot be used on rooftop residential installations (in Virginia, at least). If they are, they typically require additional electrical devices to be installed behind each panel, eliminating a lot of the potential cost savings and adding more points of failure.
While the argument against microinverters is that they add points of failure, they do eliminate a “single point of failure,” which is extremely important. When a string inverter fails, NO solar is produced. When a microinverter fails, just one panel stops producing. It’s a lot easier to wait for maintenance if you have 29/30 panels working versus 0/30 panels working.
What Brand of Inverter is the Most Reliable?
This is our opinion, so take it with a grain of salt. We’ve worked with SMA, Fronius, SolarEdge, GoodWe, Enphase, and many other inverter brands over the years. Most major inverter companies have experienced some widespread failures at some point in their history—Enphase almost went under from failures of their early micros, Fronius had major issues with their IG Plus line, and we were the unlucky recipients of a bad batch of SMA SunnyBoys back in 2018. We also experienced what I would describe as a massive number of SolarEdge inverter failures, which caused us to stop installing their inverters and pivot to Enphase back in 2021.
While there is no guarantee that a system will be problem-free forever, we have seen the best reliability from Enphase and Fronius products. Enphase publishes a 0.05% failure rate on their microinverters, which is 1 out of 2,000. They come at a higher price-point than most other inverters, but if you take a trip through Reddit, you’ll see most folks agree they are worth it.
There are more competitors entering the microinverter market, like Hoymiles and APSystems, but early reports from other installers have not given us the confidence to try them. Neither company has published failure rates, and APSystems comes with a 10-year warranty by default.
What Inverters Integrate Best with Solar Batteries?
In 2024, solar storage is much easier to integrate than ever before. With Tesla Powerwall allowing for AC-coupling, any modern inverter should integrate with it. If you happen to have a ground-mounted system and are intending to get batteries, the best inverter is probably the Tesla Powerwall 3 itself. The Powerwall includes an 11.5kW string inverter, so if you’re doing a ground-mount, the inverter is “free.”
If you have a roof-mounted system, Enphase is our pick here. It gives you the option of pairing with a Tesla Powerwall, but you can also keep the entire solar system within the Enphase ecosystem with the Enphase IQ battery system. Enphase also has a vertically integrated battery solution with the highest power output available (see our Enphase 5P Vs. Tesla Powerwall 3 comparison here).
What about V2H bidirectional charging?
If you are holding out for Vehicle-to-Home bidirectional charging (we are too), then Enphase & Tesla are the two most promising options. Enphase has announced a bidirectional charger that should be available in 2025, and Tesla offers bidirectional charging through their “Powershare” platform. It is currently available on the Cybertruck, but may be expanded to other cars in the future. If you aren’t planning on buying a Tesla, then Enphase is likely to offer more options down the road.
