Shading the condenser unit keeps it cooler and increases it’s efficiency and helps keeps my electricity costs down. The sail is high enough and mesh like so that it doesn’t trap the hot air. In fact it creates a slight wind tunnel effect. The shade it provides lasts during the hottest part of the day and a tree helpfully blocks the sun for the remainder. The unit is never in full sun this way. Keeping the weeds and other debris away from the unit so that it gets good airflow and cleaning the condenser every year also help with the units efficiency.
Sadly there are just too many variables in play. Many other changes have been made to help keep costs down such as different thermostat settings, extra insulation, and duct sealing. It does all add up to quite a bit of savings.