Covering outside air con units

[Gareth]

I see several neighbours covering their outside air con units with reflective sheets.

Why are they doing this? Is it to protect the unit from the sun? Does it aid cooling in the summer? Does it help reduce electricity costs?

One of my outside units is in the direct sun on the south side. Should I follow the crowd and do the same?

Does anyone have any knowledge beyond what’s Googleable?

Many thanks!

[CluelessToshika]

I did this last year around the start of summer, but it's hard to tell whether they had any effect, because the units were new and the climate does not present a constant temperature profile to compare year-on-year usage (according to TEPCO last year's summer kWh usage was higher than 2022, but the summer was longer and hotter, so without them usage may have been higher, but it's impossible to tell).

Subjectively they do seem to keep the top of the units cooler when in direct sunlight, which can't be a bad thing.

[RetireJapan]

We were told this is not necessary and can be counterproductive if it restricts airflow to/around the unit.