# Calculator for Watts solar panels with No Load Voltage (= Vnl) and Short Circuit Current (Isc

This is very simple calculator for characterization of solar panels with No Load Voltage (= Vnl) and Short Circuit Current (Isc)

It is based on curves V-I of real solar panels and looking at maximum Power, when first derivative V/I is =0

I short , (A)

0 Watt

To measure No Load Voltage simply disconnect any load, even battery from solar panel and measure how many volts you get.

To measure Short Circuit current= Isc, simply disconnect everything from panel and with ampt meter connect directly to solar panel.

Please note two important things before you measure anything:

1. Solar panels can be rated as "12V" , "24V" etc. In reality it can be double of that voltage sometimes. Please expect higher voltage when you measure voltage and care for your voltmeter with starting with higher voltage setting.

2. Solar panels can have very high currents. 120W solar panel means it can produce around 10A if it is 12V panel. Please use ether clamp meter and short circuit panel with thick wire (over 10AWG) or expect high currents and care that common amp meter can only measure up to 10A. If you use amp meters with over specified max current it will 100% burn the internal fuse or meter itself.