i got 3.9kW PV, which mean i multiply the sensor value by 3.9 to have my virtual power available at the PV.
I'm confused. The value supplied by the sensor is W per meter squared. How many square meters is your solar array? So, I believe you should be taking the sensor value times the # of square meters of your array, which would give you the potential power available in Watts.
Also take into account the angle of the panel and that of the sensor, and the inefficiency of solar panels, the efficiency of your charger, the SoC of your batteries, and other things. But your potential available power should be way higher than your solar panel production.
what is 3.9kW , is that the nameplate rating of your array?, or is that the actual measured power output?
For me to measure efficiency, and I have a smaller array of 1.750kW (1750W) name plate , which should not be used for efficiency calculations. An efficiency for power produced is something like this . using my numbers from sensor, and measured power from solar
Sensor value * square meters of solar. So right now 194W * 11 = 2134W , this is the total available right now for the area of the array which is 11 square meters
Now, for what is actually being produced from the array, at the same time, 230W
So efficiency is 230/2134 = 0.108 or near 11% , which is realistic