The present teachings relate to methods of operating an electrical inverter operable to deliver AC electrical power as a second AC power signal, the method including measure a first AC power signal; generating a first tuned signal dependent upon the first AC power signal; determining, using the first tuned signal, a first phase value indicative of phase of the first AC power signal; generating the second AC power signal shifted by a pre-determined first phase-difference value from the first phase value. The present teachings also disclose related products, systems, and software.