Solar panel quality testing includes an on-site visual test and a flash test. I recommend to be present at the solar manufacturer’s factory at the time of price negotiation, solar panel testing and the loading of the solar panels.
At the time, the installer said the scratches shouldn't be an issue at all for electrical output or for the long term durability of the system. However, our own research suggests otherwise. Fortunately, we've raised this to our solar company's attention, and they've been apologetic and (thankfully) willing to make it right.
On average, small and large scratches on the glass cover of solar modules are found during more than 70% of independent 3rd party quality inspections, such as those performed by Sinovoltaics Consultancy Services. This is a major and prevalent quality issue.
Some solar panel quality defects can not be detected without testing equipment, such as electroluminescence (EL) testers, sun simulators, thermal cameras, or resistance testers. However, there are also several defects that can be identified visually.
The following defects are common when testing solar panels: Lower output than stated in data sheet (we require positive tolerance on each solar panel) Other defects that we find are dirt marks on the pv module, gaps on the corner of the pv frame, poor quality labels and solar panels that do not meet the requirement of positive tolerance.
When testing, you will want to make sure that your solar panel is receiving the same amount of sunlight it would under normal conditions, so try not to move it from where it would normally be positioned. The device will then be able to give you an accurate reading of the solar panel amperage, which you can use for your calculation.