Understanding OptiTrac Global Peak
The technology everyone is talking about right now is power optimizers—electronic components that work directly with the PV module to ensure that the maximum amount of DC power can be extracted from each and every solar panel. This can be particularly advantageous when modules are in heavy shade, as the optimizer companies claim they can “save” as much as 25 percent of the energy lost through shading. However, Joachim Laschinski, technology expert at SMA, explains what the phenomenon of shading actually entails and how SMA has already solved this problem with it’s own OptiTrac Global Peak that’s included with all new Sunny Boy inverters.
What impact does shading actually have?
Joachim: It goes without saying that shading has an impact on the PV yield and cannot always be avoided entirely. This phenomenon includes shadows caused by chimneys, trees or temporary shadows cast by leaves. As such, optimal system planning ensures, first and foremost, that during periods with the highest solar irradiation as little shadow as possible is cast onto the modules. And when systems are intelligently designed, the impact of shading on the total yield of a PV system is very low. For example, a well-planned PV system that still experiences heavy shade should have significantly less than 5 percent yield reduction per year.
What is SMA’s solution to shading?
Joachim: In addition to continuously enhancing the highly robust MPP tracker (maximum power point = optimum power), which every inverter contains, SMA has also developed OptiTrac Global Peak. This function finds the global maximum power point of each PV module string which means that the energy available in any shading scenario will be used as effectively as possible.
What results is this technology delivering?
Joachim: The annual yield of a lightly-shaded PV system with OptiTrac Global Peak is only around 1 percent lower than the yield of an unshaded system. For heavily shaded systems, this figure is around 3 percent. And what we’re particularly proud of is the lack of “side effects”—the yields of unshaded PV systems that work with OptiTrac Global Peak (which they do not actually need to do) remain as high as ever. The patented process is so quick and precise that the yield losses are well below one-tenth of a percent and the function can always be activated, irrespective of the particular PV system.
How long has this technology been available and how has it been received?
Joachim: SMA launched OptiTrac Global Peak in 2009. The technology has not only proven itself, it has also prompted competitors to offer similar functions. A major advantage compared with optimizers is that the technology is integrated into the inverters and thus presents no additional cost. This gets rid of the costs of separate attachment, maintenance and exchange of defective equipment. And of course, in addition to increased yields, this also has an impact on the reliability and the lifetime cost of the PV system.
A final question: Are PV systems effective at all if they are heavily shaded?
Joachim: They can absolutely be effective and there are often other aesthetic reasons for the shade like seen in areas with high heat to reduce HVAC usage within the home. However, you should avoid operating unshaded PV modules together in a string with other modules that are frequently or regularly shaded during periods with the highest levels of solar irradiation. For most cases, this can be avoided with proper system planning. For these cases, diligent planning and system design in addition to optimal MPP tracking with OptiTrac Global Peak are the right solutions.
Thanks for the interview.
About the person
Joachim has been working in the field of photovoltaics for more than 25 years. At SMA, he has worked in different positions in inverter development and strategic product management. As a system architect, he is now responsible for optimizing the product portfolio for solar energy supply systems.
I install SMA inverters almost daily. I for the most part like most aspects with the installation process of SMA inverters.
I have one question among many.
First. The SMA rapid shutdowns are designed to parallel strings. With 4 total inputs and 2 outputs one assumes paralleling of DC strings are designed as such.
The Shutdowns have a max output of 25amps; however, the inverters only have a max input of 10amps. So, I’m unsure the reason for this. I am greatly interested and appreciative for any feedback concerning my question at hand.