Main questions: How can I work out the efficiency of a solar panel and how can I work out if the panel is relatively cost-effective? Also what type of solar panels is considered most effiecient?Let's assume that all relative values are available.Secondary question: What type of safety regulations and licenses are required to be fulfiled in order to import solar panels into the EU from non-EU countries?
The manufacturer of any serious panel should be able to provide an efficiency. That will be the STC power rating of the panel, divided by the area of the panel, divided by 000 w/m^2. But the more interesting figure is cost effectiveness, as you say, which is nothing more than cost per watt for the same class of panels. Most applications are limited by money, not by area.
366 W/square meter on March 2 and tweaked based on lattitude eff = W out/Sun W in there are special heat meters to measure W in ======== IEC 62688 Certification; and UL cert in USA