Overcoming DC Optimization Challenges
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Solar panels produce direct current (DC) electricity from the sun, but homes in the United States don’t run on DC; they run on alternating current (AC). To power a home, DC needs to invert to AC power. The inverter is the part of the solar equipment that completes this function.
Why String Inverters Need Optimization
If a home has the ideal setup for solar, a string inverter will work well. These inverters typically cost less and have easier maintenance since the inverter isn’t on the roof. However, these inverters have their challenges.
As stated in the name, string inverters have several groups of connected solar panels, the “strings.” If one solar panel has significant shade, it impacts the production of the remaining panels.
This setup also doesn’t monitor and control each solar panel, making it harder to pinpoint potential solar panel problems and comply with NEC 2017 electrical code. In response, other inverters have solutions that help optimize the production of each solar panel.
Challenges of DC Optimization
DC optimization amps up the direct current, which helps reduce the impact that shade has on each string. It also increases the overall power generated so the system can produce more. Some of the challenges that come with DC optimization include higher component counts and various environmental stressors.
High Component Count
The more complex a solar installation is, the more room there is for malfunction and error, which is why most installers try to keep the installs as simple as possible. Unlike a string inverter, optimized string inverters require power optimizers for each solar panel.
Environmental Stresses: Thermal Cycling
Environmental stressors can also decrease the longevity of an inverter and the other components of a solar array. To ensure that an inverter will last, manufacturers stress test them via thermal cycling tests. These tests put the inverter through extreme heat and cold to determine how long it will take for the inverter to stop functioning in extreme weather conditions. The warranty for the inverter protects the homeowner in the event the inverter faces these problems.
Addressing Optimization Problems With Inverters
An optimized inverter will help the solar array produce the most electricity possible. We believe that there are three inverter brands which have optimized their inverter technology to meet these needs.
Enphase inverters use a microinverter underneath each solar panel. These small inverters are used in lieu of the central inverter used in most string inverters. While you can add more panels to these with ease, they do cost more, and maintenance has more complications.
Recent SMA Inverter Optimization Updates
While SMA uses traditional string inverter technology, they have added a Solar+Solution so the inverter complies with NEC 2017 modular level shutdown, allowing for more control of the system.
SolarEdge Power Optimizers
SolarEdge uses power optimizers to enhance direct currents in each solar panel, so shade on one panel doesn’t negatively impact the remaining modules. These optimizers also help the installer determine potential problems with specific solar panels, providing ground-level access to the central inverter.