Some meters register injected energy as consumption, this is the way company prohibit injection.
Any grid tied inverter has built in anti island protection, but some providers ask for external protection, an anti island kit agreed by that company.
Fire safety regulations are in place for PV systems, if panels are placed on non combustible roof or ground rig not special fire protection class panels must be used.
If you use tin or ceramic tiles on metal frame, or concrete slab is no problem, is roof is combustible you must use first class fire protection panels.
PV systems are hazardous for firemen because is no way to cut off string voltage when is light outside, optimizers may be a solution, but they are proned to fail in harsh outdoor conditions, from my experience average life is 2 years.
You must pay attention how build and wire your system to minimize fire hazard, protect wiring from metal objects that can pierce insulation, be sure that water not sip inside of connectors, corrosion may end in fire, protect wiring from sun light as possible.
Avoid stupid things.
Can you see something stupid in those images?