The IC size relays were 5V, so no go, but I did find a small 12VDC DPST that should work. Not sure what package name, but looks like a typical relay, only smaller. Rigged a quick mock-up and that might work out. Since the battery and system will be connected when the Sun is high, they should damp the voltage enough to not smoke the relay coil.
If this works, there will be enough power to operate everything during the daylight, then drop it all out at night while conserving battery to cover during clouds or storms. For Winter, I'm not sure, but I have brackets to tilt the solar panel if needed.