Welcome back ka-Toolbox! Here we are again with another episode of… "Quick answer for the quick question" But before we start, shout to JoyMasoy TV. For our Toolbox Electronic Hobbyists there. Visit now and we will learn a lot on his channel about repairs and DIY. Also, shout Sir Richard Stealth Tees. So, let's get back to our discussion. One of the questions when we start solar, is why there are two Voltage and current Rating of each Solar Panel, But is there only one Power Rating? What are these Ratings? First ratings are the Vmp and Imp values. The second are the Voc and the Isc. But before that, in Solar we have what we call STC or Standard Test Condition. This is the test conducted in the Laboratory of the Solar Panel manufacturer. In Standard Test Condition or STC, the condition here is perfect.
The Irradiance of the Sun is at 1000Watt/sq.m. The Air Mass is at 1.5. And the Temperature is at 25 Degrees Celsius. Because of that the manufacturer gets the values that the Solar Panel produces whenever the condition is perfect those are the values they put in the Specification that are usually found on the back of the Solar Panel. Let’s start with Vmp and Imp.
Vmp or Maximum Power Voltage is the Voltage value when the Solar Panel produces Maximum Power. And the Imp or Maximum Power Current, is the Current value when the Solar Panel produces Maximum Power. For example: This Solar Panel has a maximum power of 150W. When the condition is perfect, the Vmp of this Solar Panel will hit 18.2V, and its Current is 8.25A. So, 18.2V x 8.25A = 150W And that is the output of our solar Panel. But this is far from the actual scenario. Because in fact it is too high and difficult to reach 1000W/sq.m in Irradiance alone. Especially the Temperature of 25 Degrees Celcius. The warmer the Solar Cells or Panel gets, the lower its harvest. Now we are in Voc and in Isc. Let’s start with Voc or Open Circuit Voltage. We can get this Voltage value through the DC Voltage Tester which is parallel to the Solar Panel itself. When testing the Voc, there should be no other connection to the Solar Panel, except for the tester we will use. If you want to get the most peak value, sunlight should be good during testing.
But what is its use? he use of Voc value is very important in computing the Solar Charge Controller required in the Setup, because we will base our computation of the Total Voltage of the String or Array of the Solar Panel in Voc and not on the Vmp. Now, let's proceed to the Isc. Isc stands for Short Ciruit Current. Contrary to Voc earlier. Voc is OPEN Circuit. and the Isc is SHORT Circuit. We can check the value of Isc through DC Current Tester. As with Voc testing, the Solar Panel must have no other connection during testing. And the sunlight should be good during testing to get its most peak value as stated in the Specification.
But where can Isc be used? Isc can be used to size equipment, Circuit Breakers or fuses and other System Protections. So, that's the whole of our discussion. If you are new to this channel, subscribe and press the bell button so that you are always updated on our uploads. Thanks Ka-toolbox! "Please subscribe".