All solar panels should have a blocking diode to prevent batteries/supplies discharging in to them.
They also need a regulator or limiter to ensure they do NOT boil batteries (above ~14.4V) and loads - typically above 16V.
Most 12V loads operate or tolerate 8V-16V; few exceed 16V reliably. Some may not operate below 12.3 or 12 or 11V etc, but they should not be damaged from 0-15V etc.
And an AGM will accept charge at a greater rate than wet cells.