My first time shopping for a mini split I remember seeing SEER all over the place and never really knowing what it meant. So I looked into it and found that SEER stands for Seasonal Energy Efficiency Ratio. It is the American standard for measuring the efficiency of an air conditioning unit. The higher your units SEER rating, the more efficiently it runs, the lower your electric bill will be; compared to if you purchased a lower SEER air conditioner.
Still I’m the type to want to really understand what things mean so I dug a little bit deeper. The SEER ratings of an air conditioner is determined by the AHRI (Air Conditioning, Heating, and Refrigeration Institute). Measuring the cooling output (BTU or British Thermal Unit) during a cooling seasons(125 days running 8 hours a day) and dividing it by the total electric energy input (in kilowatts) for that time will result in the air conditioners SEER rating. This is why SEER can be measured in BTU/kWh. Typically a higher SEER units will have better ways of retaining or dispersing energy; such as larger coils, multiple compressors, variable refrigerant flow or a variable supply air flow are examples of this.