How to measure solar panel voltage using arduino?

[DaveE]

When I started this thread I was hoping someone would respond "Hey, this device does exactly what you need". I'd prefer if there was a device that could be bought ready.

Must not have looked too hard...
Here's the first one I found, I'm sure there's many others:
https://www.dataq.com/products/di-4730/

Try a google search like "500V data acquisition".

 

[Baluncore]

Powering with one panel.... Voc=38,1V; within the range of a buck converter. Even two panels will be within the range. I'm not sure if that is a good idea though - it will unbalance the strings as it will load one panel in one string.

If the isolated instrumentation required 20mA at 15V, an ideal switching buck converter running on 38 volts input, would only need a current input of 20 mA *15V / 38V = 8 mA. That is an unbalance, but I don't see it as a big problem.

By accumulating charge at a rate of say 100 uA in a capacitor, from the string-voltage sensing-chain, that charge can be dumped through an opto-isolator, which eliminates much of the instrumentation current that must come from the lowest isolated panel.

When the light level is low, the controller should reduce power by sleeping. Your system should allow all relays to open, automatically switching the PV panels into the low-power configuration.

 

[Rive]

When I started this thread I was hoping someone would respond "Hey, this device does exactly what you need".

the only safe solution I can suggest is to get a DMM with remote (bluetooth?) connection.

Google 'DMM serial', it's still not late...

TP4000ZC is kind of 'dirt cheap'.

I still suggest to go for bluetooth, though. Good insulation, lot harder to mess up.

On second thought, I suggest to stop. The difficulty to do this safely and effectively just does not fits you.