• Adam H. Cooke

The Great Debate Solar MicroInverter vs. Power Optimizer I

Reliability is an important factor when considering the options for a solar photovoltaic systems. Clients first inquire about the reliability of solar panels. Solar panels are extremely reliable and rarely fail in a solar energy system. Not the solar panels, but the electronics are the most common source of service problems and failures in a system.

The names of the major players will not be discussed in this article. It doesn't take long to find out who the major players in each area are. You can either leave it to me or have a discussion with me during a consultation.

Inverters in The Good Ole' Day

Inverters convert DC power into AC power, which is compatible with your utility electricity at home or in your business. Inverters were used to convert power from panels strung together. These inverters are also known as central inverters and string inverters. They were not reliable. There were some brands that were more reliable than others, while other product lines had serious issues. They were not designed to last as long as a solar energy system. Often, the replacement of the inverter was included in the investment analysis.

If a string converter fails, the whole system stops producing power.

This component can be replaced in a few minutes or it could take a lot of effort. Sometimes, a rework was necessary if a replacement was not possible. They were very heavy. Installers might need to climb onto the roof to disengage solar panels before replacing them due to poor installation techniques. Perhaps most important, some cases can be difficult to replace because of changes in the electric code.

The New Breed of Inverters


Micro-inverters were commercially viable in the 2000s. This technology combined a single solar panel and a single small-sized inverter, a microinverter. This system architecture has clear benefits and some drawbacks.

Because there is no high-voltage DC power from the roof to micro-inverters, they are safer than DC string or DC string inverters. Because each panel is connected to its inverter, it can be shade resistant. It is easy to mount the panels on the wall without a bulky, heavy box. Panel-level monitoring is revolutionary. The system is fault-tolerant, which was the main selling point. This means that even if one or two of the microinverter fails, all other inverters will continue to produce power.

Micro-inverters have a number of disadvantages, including cost and serviceability. Although microinverter can be more costly, they are still affordable when you consider how much energy they produce and other reliability factors. Opponents dislike the fact that micro-inverters can be replaced on rooftops. The likelihood of making a mistake increases because there are so many of them.

There were many reasons for early opponents to believe they were right. Microinverter failures were frequent in the early generations. Warranty replacements were easy to find and, like the plan, these owners weren't completely without power production. The technology was rewarded for those who stayed with it in the hope of further improvements. There are many generations of microinverter models, and the most recent generations have an impr