45 amp TriStar pwm limit

Well, this is 'Whit', I haven't seen a lot of degradation, but haven't really been looking or expecting much. I have a panel made in the early 80's producing nicely, though a monocrystalline. My systems tend to be over sized array to battery. I don't use a generator.

I never expect a solar panel to produce over 75% of the panel rating. There is a difference between the 'flash test' to get Standard Test Condition, STC rating and the Normal Operating Cell Temperature, NOCT values. These tend to be about 75%.

These means you can expect about 75 watts out of a 100 watt panel. This is what you can expect when the panels are warm/hot. You may approach Standard Test Conditions(STC), in very cold winter days with good direct sun, but it will be rare.

Also a well designed system will rarely NEED to produce maximum current. Typically systems are designed to reach full charge and stay in the top 80% of battery capacity on sunny days. At around 80% a flooded lead acid battery accepts less current. So there will be no need to have the system producing at maximum current. Even after a cloudy day and your battery bank down to 60%, it will start charging before the sun reaches solar noon when maximum production is possible and you may never see maximum production and the cells will warm, even in winter! So less than STC will be normal. I would never sweat these panels in 20f days.

These days some manufacturers are printing out and posting the NOCT values on their panels or at least in their literature. Here are some examples;