Designing a High-Performing Solar System

Designing a High-Performing Solar System

APRIL 16, 2014

A solar photovoltaic (PV) system that performs up to or beyond its predicted output can make the difference between a successful project and a lackluster one. Determining a PV system’s capacity begins early in the design process, so careful choices need to be made from the outset.

Energy production at the time of design is predicted using modeling software that takes many parameters into account, including system configuration and environmental factors. The model provides a tool by which the design can be changed to maximize output per dollar invested. Budgets and upfront costs typically drive projects, but by assessing the total cost of PV systems over their 20-25 years of life, design features can be included that will yield the highest performance over the system’s lifespan.

Optimizing the system

Designing a high-performance PV system starts with an understanding of the site limitations and selecting a solar panel that is well-suited to the location. It is important to note that the published panel efficiency (percentage of light turned into power) only tells part of the story. If a site has partial shading, for example, selecting a panel that produces more power under low light conditions is ideal. This can be determined from the efficiency curves for the panel and can significantly impact the amount of power the system produces.

There are other techniques that can be implemented during the design phase to ensure the system will produce the greatest amount of energy possible. For example, voltage drop, which is the energy lost as power travels through cables and other passive system elements, affects the vast majority of electric systems. The higher the voltage drop the more power is lost as heat in the cable. Correctly sizing cables and reducing cable lengths to a minimum through efficient array layout and combiner locations minimizes voltage drop, creating a higher-performing PV system.

Another technique is using high-efficiency transformerless inverters. Every transformer loses a percentage of incoming power, so by eliminating transformers, the overall system loss can be reduced. Additionally, most solar systems still need a step-up transformer to connect to the utility. By using super high-efficiency transformers the loss can be kept to a minimum.

Not all factors are controllable

Although a design may predict a certain amount of energy production, there are various factors that can impede it, resulting in less than optimal output. Some of these factors are uncontrollable, like the accuracy of predicted weather. The snowy winter season of 2013-14 is a prime example. Many PV systems will experience decreased output because snowfall exceeded predictions in many parts of the country.

Design details that are easily overlooked can end up having a significant impact on a system’s long-term performance. Making the right design choices based on the factors that can be controlled will allow a PV system to produce the optimum amount of electricity and increase energy savings over the long term.

Tags: Energy, Power


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Government & Institutional

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