Basic queation - What kind of circuit allows me to throttle the power draw from two different supplies? i.e. 80/20 from a battery bank and utility power, respectively? Or 60/40, or 100/0?
Main idea - My utility company has off-peak ($0.048) and on-peak ($0.283) rates for electricity. I want to build something like a Tesla powerwall to capture the low cost power for use during on-peak times.
Specific problem - The battery bank I have in mind could provide 3KW if necessary, but I want the option to "throttle" the maximum output of the battery supply and supplement with mains power as necessary.
Example - litmiting to 2,800 watts:
Demand is 3,500 watts | Battery supplies 2,800 watts | Mains supplies 700 watts
Demand is 2,500 watts | Battery supplies 2,500 watts | Mains supplies 0 watts
Summary - I want to draw from my battery bank as much as possible (while limiting the output a bit to increase their lifespan / cycle count) and supplement with power from utility as needed when demand exceeds what the batteries can supply.
-Load Balancing- Seems appropriate if I want to draw equal power from 2 or more power supplies. Does not work if I want 80 amps from one and 20 amps from the other..
-Current monitoring- Using hall effect and placing some variable resistor in the line to adjust the voltage on the mains supply to limit current. But can this allow me to throttle the mains current down to 0?