Any solar system owner and operators can now obtain mathematically derived performance bench marks on line, and stop wondering about how their system is performing.
A visitor to the website, www.wattminder.com, simply enters a brief set of values for 'vital statistics' of a solar system. The free performance predictor will output a look-up table for a number of environmental conditions, that this visitor's PV system should be producing at that instance—given the Sun's position and the solar array's location and attitude, as well as temperature of the solar panel(usually 10 to 20 degrees higher than the ambient).