If the installer or salesperson talks aout a 190w or 250w panel they are talking about the max power rating of the panels.
Reading solar panel labl.
Solar cells are typically about 4 5 wide by 4 5 tall.
The max power rating in watts that your solar panels are rated at is the figure that everyone quotes when talking about panel size.
Right below the electrical ratings indicate the major performance output characteristics of the panel.
The solar panel description usually starts with the name of the manufacturer then the category of solar module and afterward the solar panel wattage.
It starts to get tricky when you move away from battery based solar systems and the 12v increments are no longer necessary.
The example photo of a solar pv label indicates name and address of the manufacturer and the solar module type blackened.
Commercial solar panels have 72 cells but they are much too big for residential roofs.
On the lower part of the label there are icons of all the certifications this specific panel has passed.
Residential solar panels have 60 cells and so are about 3 feet wide by 5 feet tall.
They have too high of a voltage to charge a 12v battery bank with a traditional charge controller but too low of a voltage to charge a 24v.
Sw manufacturer solarworld 255 watt poly q cells q peak g4 1 product line of polycrystalline module 295.