How should solar installers prepare for inverter failure?

As inverters get smarter and smarter, installers should plan ahead for inverter failure in older, lower-voltage projects. Most solar systems these days use 1,000-V or 1,500-V strings, a considerable jump from the 600-V strings of the past. Richard Baldinger, group leader of marketing and sales support at Fronius, said the inverter is often the first part of a project to need maintenance or replacement.

“We have to have realistic expectations and realistic promises on equipment endurance,” Baldinger said. “We all know it’s power electronics, and the inverter is the most stressed component of the system.”

Inverter manufacturers take different approaches to ensure installers aren’t left in the dark when an inverter failure inevitably happens. Fronius uses “field serviceability” to set itself apart for inverter reliability. Baldinger emphasized Fronius inverters have a design life of 20 years and are built to last, but the company is also realistic and prepared for any problems that may occur in that lifespan.

Solar installers who go through training to become “Fronius solutions providers” are taught how to exchange inverter components in the field if they happen to malfunction or break. When installers complete the training, they can purchase a spare parts kit to keep on their truck that’s tailored to their specific inverter fleet. If a problem does occur, the installer can troubleshoot with the help of Fronius’s online monitoring and troubleshooting tool or a phone call to tech support if need be, then get the project back up and running right away.

When Fronius inverters are still under their 10-year warranty, installers can file warranty claims to get the replacement parts for free.

“They have the spare part on the truck, exchange it in the field, and within one truck roll and probably less than an hour, the system is up and running again,” Baldinger said. “I think this is the scenario we need as an industry because it increases uptime, increases customer satisfaction, makes the solar installer’s service business way more attractive and way more streamlined, cutting the truck rolls in half, and it’s also less wasteful. You’re not throwing away a complete unit when it’s just a little board or a little component that is in error.”

Extended warranties

SMA Solar’s strategy for easing fears of inverter failure is through its warranty program. All SMA inverters come with a 10-year warranty, but that warranty can be extended for another five or 10 years at any point, even on year nine, day 364 of its initial warranty, said Blair Reynolds, SMA’s residential product manager, adding that that policy is always subject to change.

Giving customers the option of a factory warranty for up to 20 years gives contractors a way to differentiate themselves. SMA makes inverters for all three market segments—residential, commercial and utility-scale—and Reynolds said he sees the long warranty giving all three an advantage.

For residential and small commercial applications, Reynolds said, “We see them purchasing the warranty extension and offering it as a way to differentiate themselves because they’re of course operating in a highly competitive bidding scenario.” He said that on third-party-financed projects, a 20-year warranty can look especially attractive since PPAs or leases are often for a term of 20 years or more.

As for utility-scale projects, Reynolds said “it can make a big difference in the production uptime of a utility-scale power plant, which can make a big difference in the financing.”

SMA also has a utility-scale solar O&M arm for contractors looking to outsource that function. Reynolds said the team services all types of inverters, but is especially advantageous for installers that use SMA inverters.

“Because, of course, we know the inner workings and we can trace the serial number back to the exact parts that were used to build that inverter way back when,” Reynolds said.

In addition to warranty and O&M services, Reynolds said SMA’s Smart Connected monitoring service is always available for free for residential inverters and will soon be rolled out to commercial inverters too. When the monitoring detects something going awry, SMA will ship the replacement part to the jobsite.

“That way the installer only has to go to the house or the jobsite, the business, one time to do a swap-out of either the inverter or the components that we deem to be experiencing a failure,” Reynolds said. “It really does take a lot of that burden off of SMA installers about how to prepare for an inverter failing compared to our competition, perhaps.”

Long lifespans

APsystems works toward longevity by combining the long lifespan of microinverters with extra upgrade-ability. APsystems microinverters have a design life of 25+ years in the United States.

“The design life has to be able to last that long, and the technology has to likewise be compatible with that timespan,” said Jason Higginson, senior director of marketing at APsystems.

When new codes like Rule 21 come into effect, APsystems is usually able to update its microinverter software remotely.

“When the rules change, the software has to change as well so that the product performs to meet those standards,” Higginson said. He said APsystems’ remote upgrades make it easy for contractors to stay current.

APsystems was founded in 2009, so even its first installations haven’t run through their 10-year warranties yet. Since the design life of the microinverters are more than double that, Higginson said by the time they reach the end of their lives, it will likely be more cost-effective for contractors to upgrade their whole system.

“If you could choose between taking your system that’s run a life of 25 years, and using that same system for another 25 years, or using a much more modern, efficient system for another 25 years, the business case will almost always point you toward the modern, updated systems,” he said.

But if contractors are looking to replace inverters before the rest of the system, he thinks it wouldn’t be too difficult.

“Once that 25-year-old system has reached the end of its life and some components start failing, it’s possible you can find replacements, especially with the Internet today,” Higginson said. He points to websites like EnergyBin, where contractors can list solar equipment they’re looking to sell.

If an APsystems microinverter does fail, he said most of its current inverters are still compatible with older solar projects, with the exception of some with very old cabling.

“There have been a lot of internal changes in the software but very few mechanical changes in how it fastens and how it connects,” Higginson said. “Our product currently maintains quite a bit of backward compatibility.”

Role of power optimizers

In cases where products are not backward-compatible and the string voltage does not match with the inverter, installers can look to power optimizers to bridge the gap.

“That’s definitely a problem that a product like ours can help you solve,” said Hanan Fishman, president of power optimizer company Alencon. Fishman said Alencon optimizers have a fully configurable output range relative to the input, meaning installers can step a 600-V string up to a 1,500-V inverter.

Fishman said the key is for installers to have a plan in place for when and if an inverter failure occurs.

“An inverter failure is somewhat akin to a heart attack. I mean, the bottom line is, your inverter goes, this isn’t like a productivity issue, you now have no power,” he said.

Some contractors may even find themselves needing service on an inverter whose manufacturer is no longer in business. In those scenarios, they may need to go for an optimizer to connect an older array string to a new smart inverter.

If installers carefully consider their inverter investments at the beginning of projects, keep a close eye on monitoring during a project’s lifetime and have a plan in place for when inverters inevitably need to be fixed or replaced, they can give their customers the most value for their solar investments, whether it’s a residential home or multi-megawatt farm.