It's a subset of the wavelengths of sunlight, specifically just those which add up to the color of the moon.

The problem is not the "quality" of the light, it's the quantity: moonlight has way less brightness than sunlight, specifically from here you get that the brightness of moonlight is 0.05 - 0.3 lux whilst that of direct sunlight is 32,000–100,000 lux.

Less brightness pretty much directly translates to less power produced by a solar panel.

So you can actually generate power in a solar panel from moonlight (photons of the same color have the same wavelength hence the same amount of energy, so are equally capable of inducing electron release independently of how those photons got there), it's just a ridiculously small amount compared to how much you can generate under its optimal operating conditions (under direct sunlight) because moonlight is made up of far fewer photons than direct sunlight.