Moving rows of solar panels farther apart can boost efficiency and improve economics in some cases by allowing greater airflow to disperse heat, according to new analysis from the National Renewable Energy Laboratory.

Researchers looked beyond current operating assumptions that typically account only for the amount of sunlight, wind speed, and ambient temperature. They included the accompanying heat that also can affect power output.

System layout, including how modules are spaced and angled as well as their height off the ground all can affect airflow, researchers said. They said the temperature of a PV module is second only to the amount of sunlight it receives in terms of impact on module electrical output.

A module’s maximum power output drops by 0.3% to 0.5% per degree increase in module temperature. Sunlight is the primary driver of module temperature; wind speed has a secondary effect.

The analysis relied on NREL’s System Advisor Model and showed that a greater separation between rows would improve PV system performance by allowing airflow to cool the solar modules.

The research could be relevant for agrivoltaics, in which crops are planted near to or below solar panels. Changing land usage for different layouts would affect crop placement, which could affect wind flow.

By further distancing the panels, the amount of ground-reflected irradiance on a solar module rises and the incidence of modules casting shade on each other falls. Increased spacing also allows greater wind flow, which can result in lower module temperatures and higher energy output.

The researchers did not specify how far apart the panels should be because each PV system is different and depends upon local conditions. They said, however, that the greatest improvements came in climates with low average annual ambient temperatures and moderate to high average annual wind speeds.

NREL environmental engineering undergraduate Abigail Brown rakes soil over flower seeds at what will be the pollinator habitat at the Photovoltaic Central Array Testing Site on NREL’s South Table Mountain campus. Credit: Werner Slocum / NREL

The greater row separation comes at a cost, the researchers said. Notably, more land is needed and wiring costs rise as the arrays are more spread out. The researchers determined, however, that the benefits outweigh the costs in many cases.

The paper “Technoeconomic Analysis of Changing PV Array Convective Cooling Through Changing Array Spacing” appears in the IEEE Journal of Photovoltaics.

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