Solar panel efficiency

[Orchidius]

Hey,

I'm looking into getting some solar panels, but I'm left with some questions regarding their efficiency. Mostly the info you get are the wattage and the type (mono/poly), but it's a lot less clear what their efficiency is. An older 100w panel won't put as many amps into the batteries as a newer one, but how do you spot the difference? At what point is the difference not worth the financial gain anymore?