How To Pack PV Arrays To Improve Cooling

Photovoltaic panels by definition work in sunlight, and this means that they are warmed by the sunlight.  This is another one of mother nature’s little jokes:  too much sunlight that over heats the materials reduces the useful energy production, and eventually can damage the systems.  So, PV panels need to dissipate heat.

This is usually done through passive radiation and by convection.  PV panels have aluminum frames which radiate heat out the back and sides.  And many panels are spaced out and mounted so that air circulation can convect away heat.

This winter, researchers in Utah report a simulation study that suggests that the common layout of PV farms is not optimal [2].  In fact, if the way PV farms are laidout were based on intuitions about convection, the intuitions are wrong, at least according to this analysis.

Fig. 1. Top view of four study cases of idealized solar farm arrangements. Dark areas represent the heated patches and the dashed line represents the perimeter of the control volume for each case. (From [2])

Basically, they find that bunching the panels together in large groups with a lot of room betwee drastically increases the cooling, which should increase power production.  The improved cooling is due to much larger “plumes” of air.  Presumably this would mean a significant updraft, and possibly noticeable winds.

Assuming this analysis is correct for real systems, then are there down sides to packing them closely?

Conventional layouts are partly done for convenience of construction and maintenance.  The hypothesized optimal  “compact” layout amounts to islands 700+ meters on a side, which may be harder to site in the first place, and harder to access for repairs.  I doubt that this is a fatal drawback, though some operations might need to be redesigned.

The enhanced plume might have an impact on local microclimate.  In humid climate it might even cause local haze, and in dry climate it might pick up dust.  Either of these could reduce productivity.

It might also affect wildlife.  Some birds and flying insects might benefit from the updrafts, and it is possible that the soil under the large patch might be significantly cooler.  The cooler soil might promote retention of moisture, though the increase convection might dry the soil.

It looks to me like there is scope for some detailed experimental studies to (a) confirm the theoretical analysis and (b) examine some of the local side effects.

---

1. Emiliano Bellini, New approach for convective solar module cooling, in PV Magazine, November 12, 2020. https://www.pv-magazine.com/2020/11/12/new-approach-for-convective-solar-module-cooling/
2. B. Stanislawski, F. Margairaz, R. B. Cal, and M. Calaf, Potential of module arrangements to enhance convective cooling in solar photovoltaic arrays. Renewable Energy, 157:851-858, 2020/09/01/ 2020. http://www.sciencedirect.com/science/article/pii/S0960148120305814