How to monitor PV DC voltage

[BartSr]

I own a very old PV inverter make Mastervolt.
I would like to measure the DC voltage of the solar panels string. I need this info for investigation. I like to buy an intelligent inverter/ controller for battery charge discharge. That one can also handle PV panels but it's unsure if PV panels start voltage is high enough. So prior to purchase I want to monitor the voltage. I know DC voltage of 4 panel string might reach dangerous high voltage so care is obvious. Any idea for a measuring sensor which can be work with Domoticz?

[waltervl]

Easier to wake one day early in the morning and read the solar panel voltage from the display of your inverter and mark when the inverter switches on inverting ..
It is not that it will start one day different from the other so no need to monitor it for a long time (days/months) for this use case.

Also I am not aware of a device that can do this. Everyone is using the inverter for this.....

[BartSr]

Thanks for reply Walter. As said, this is an old Mastervolt inverter without possibility to peek in the inverter. Also none display.

[gerardvs]

There are plenty of modules at the (in)famous Chinese web-shop. But be careful when connecting the module since it most likely has to be isolated.
But if the measurement is only once or twice then you could use the most simple analog voltmeter and a cheap camera to create a time-lapse video of the morning/evening to see how the voltage behaves. Sounds silly in this digital age but it works.
The datasheet of the panels (or label on the back) should also provide you with the required information.