People who sell variable speed pump systems want you to think they save energy. In reality anytime you vary the speed of the pump, it uses more energy per gallon produced.
1 HP pump at full speed puts out 10 GPM and pulls a full 1 HP load, which is 10 gallons per horse power.
When slowing down the RPM, the amps will drop by 50%. This is why so many people think, and can make you believe, they are saving energy. However, when slowed to 50% load, the pump is only moving 1 GPM, and using ½ HP load. That is only 2 gallons per horse power, or 500% more energy used when varying the speed of the pump.
So there is NO return on investment. I could write volumes on how much extra it will cost to replace these expensive SQE systems every 5 years or less, compared to a less expensive standard type pump that should last 20 years. People who sell SQE pumps make a lot of money because, people who buy SQE pumps spend a lot of money.