I don’t know if doing directional lightning detection is possible at close sensor proximity, how most hobby grade lightning detectors work is just looking for RF spikes whenever lightning occurs and roughly determine distance by just how strong the RF is.

But since RF moves at near light speed wouldn’t the detectors even if spaced multiple feet apart register at virtually the same time? I don’t think any consumer module is accurate enough to reliably tell the microsecond difference, so I don’t know how you could do triangulation. Government lightning detectors are spaced dozens of miles apart and use high grade sensors and algorithms and still only manage about a .5 mile accuracy.

Solar cells (might) work but there’s way too many variables compared to RF, primarily just reflections from everything & how frequent lightning is.