One of the biggest variables in the power output of your solar array, besides positioning, is temperature. Let us look at the SMA America Sizing Tool. The input variables would be SB 5000US,  Evergreen Solar ES-B-195-fa2, and Irradiance of 1000W/m2. I will use my Zip Code 46142. You can use your location if you like. Temperature, -22 F and 104 F. Then click “Get Sizes”, then “Predicted Output”.

If you look at the 20 panels data points for the inverter output. -22F is equal to 4090 Watts 104F is equal to 2812 Watts. The difference is 1278 Watts!!!

Now lets look at something more typical. 23F is equal to 3633 Watts 86F is equal to 2994 Watts. The difference is 637 Watts!!! With a temperature difference of 63F. The wattage difference is over 15% of the total array wattage. The specification that you want to pay attention to is called, Module Temperature Coefficient of Power (PKpmp), in this example, -0.49%. As the temperature goes down, the power goes up. Standard Test Condition for temperature is 77F.

The benefit of the increased array output at cold temperatures is that they occur in Winter. With Winter, comes a decrease in solar insolation. A a really cold day you could potentially have a higher peak output then you would in the summer.

A good thing to note, Kaneka make a panel that only has a Coefficient of Power -0.20%. At the aforementioned temperature extremes, the wattage difference is only 609 Watts as compared to the 1278 Watts. Over time, that can make a big difference.