A untypical application, so Im not sure what equipment is out there to do it the best (cheapest).
There's basically 2 services, 120/240v single phase. The main house/shop service (200A - 2x100A subpanels) and a grid-tie solar array 10kw (60A). Same transformer/phase into separate disconnects side-by-side. What's wanted is to meter the main service and the solar, preferably in watts, and combine the two for a net value...the solar minus the main (or visa versa)...and if there is a significantly positive net (solar production greater than usage), then operate an optional load (via relay). The reason being, the energy is much cheaper for what is used directly from the solar, vs selling it and buying back.
Some sort of way to have 4 CTs (2 on each service) connect to some instrument that would figure out the net watts and close some contacts if there is say 3500watts extra, then open when it reaches 0 watts (looking at a 3000watt load). Any ideas??
