Does a solar panel with a “Max Power” rated at, say 190W, really produce a maximum power of 190W when it is on your roof in the blazing sun?
Short Answer: Not on your nellie!
The max power rating (in Watts) that your solar panels are rated at is the figure that everyone quotes when talking about “panel size”. If the installer or salesperson talks aout a “190W or 250W panel” they are talking about the “max power” rating of the panels. This rating is based on the power output measured from that panel under “Standard Test Conditions” (STC) that, unfortunately, are a long way from “Real World Operating Conditions”.