As stated before solarud cannot increase your modules Wp, however since day one that you install the modules and they are exposed to the nature elements they start to loose some efficiency because of dust and dirt. In real world tests Solarud yelded 4% increase in just 10 weeks of use. This was measured using two identical strings, that were fully cleaned and then solarud was installed in one of the strings and we monitored production during 10 weeks.