Is it possible to start fire using moonlight?

Moonlight has a spectral peak around 650nm (the sun peaks at around 550nm). Ordinary solar cells will work just fine to convert it into electricity. The power of moonlight is about 500,000 times less than that of sunlight, which for a solar constant of 1000W/m^2 leaves us with about 2mW/m^2. After accounting for optical losses and a typical solar cell efficiency of roughly 20%, we can probably hope to extract approx. 0.1mW with a fairly simple foil mirror of 1m^2 surface area. Accumulated over the course of a whole night with a full moon, this leaves us with around 6h*3600s/h*0.1mW≈ 2J of energy. That’s plenty of energy to ignite a fire using the right chemicals and a thin filament as a heater.