To measure the solar panel voltage and current follow these steps:
1- Create a program with two Analog Read Pin blocks, P1 and P2, and upload it to the micro:bit. This puts P1 and P2 in analog input mode.
2- Connect jumpers from the Solar Current Monitor and Solar Voltage Monitor on the Solar Battery to the P1 and P2 inputs on the micro:bit.
3- Create a program that will loop on analog read P1 and P2 and printout the results. The readings will be between 0 and 1024.
4- The solar voltage will be equal to (( 3.19V ÷ 1024) x 2.4 x reading) . For example a 3.7V solar voltage will give a reading of 495 on P2.
5- the current will be ( ( 3.19V ÷ 1024) x 2.4 x (P2reading – P1reading) ). One bit reading is approximately 7.5mA. Because of the precision of the micro:bit A/D, readings below 30mA or 4 bits are not significant.
6- The solar panel voltage is ( 3.19V ÷ 1024) x 2.4 x P2reading.
7- The solar panel voltage is modulated by the battery charger U1 and may fluctuate depending on the charger state.
8- To measure the unloaded solar panel voltage re-program micro:bit pin P1 as a digital output and write a zero to it. Connect it to the charger on-off. The solar panel voltage is available on the micro:bit P2 programmed as an analog input in step 1.