Help with circuit to alternate a light switch with solid state
I can't quite figure out what you are asking. I think it is, "How do I replace the relay at one end of my two-way lighting circuit with a solid-state solution?"







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. (a) What you've got. (b) A double SSR solution.

You can avoid the need for two controller outputs to control the two SSRs as shown in Figure 2.



Figure 2. For single GPIO control wire the opto-isolator LEDs as shown.

When GPIO is low L1 will be lit. When GPIO is high L2 will be lit. Note that if GPIO is in tri-state that there may be enough current - even at 3.3 V - to turn on both.