Optimizing PV Systems
BY gREG sMITH, sENIOR TECHNICAL TRAINER, SMA AMERICA
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Optimzing PV Systems eFeature | July 2014
As a solar professional, it’s important to carefully consider the photovoltaic (PV) design that will generate the highest return on investment (ROI). While the specifics may differ between residential and commercial systems, the themes are almost always the same: fast install and fast payback. However, the really savvy PV companies are starting to consider more factors, such as PV system optimization, which will help keep them profitable for a long time.
Optimized and properly maintained PV systems have a much higher rate of return and produce more energy over the lifetime of the plant. However, there is much more to optimizing a PV system than just simple string sizing. The right inverter choice can make the difference between a worry-free install and an operations and maintenance (O&M) nightmare. The largest integrators in North America are realizing that there is no one-size-fits-all inverter solution and that they must expand their product portfolios if they are going to extract every last watt-per-hour from their systems to gain better ROI.
WHAT DOES PV OPTIMIZATION MEAN?
PV plant optimization means different things to different people. To some, it is the number of modules they can fit on a string, or AC combiner bus bar calculations for large commercial rooftop projects. Others focus on the inverter choice: central or string inverter, string or micro inverter. Or, perhaps they are considering using DC optimizers. For many, “PV plant optimization” refers to the ROI of the installed system.
According to Andy Black, solar financial analyst and CEO of California-based OnGrid Solar, PV system owners can now get a very close estimate when they want to know how long it will take to recoup their investment. Black said, “…the payback question can now be given a serious answer, backed by solid math and accounting.”1 Basically, the math involves comparing the savings on an electric bill year-by-year to the amount of the loan taken out for the PV plant. Although it sounds easy enough, the system payback speed depends heavily on a few moving targets: local weather conditions, utility rates and solar rebates and incentives, just to name a few.