Mixed voltages at negative common connection?

[carilchasens]

60V DC and 12V DC, both with the negative on a common ungrounded connection... what would you call a setup like that? What would be the effect? The thing I have in mind is an ungrounded photovoltaic system, with the 12V battery negative and the 60V PV negative on a common connection together at the charge controller.

 

[hevans1944]

I see nothing wrong with that. What is the battery used for? Are you going to charge it from the PV panel with a buck converter between the PV panel and the battery? That will work.

 

[Harald Kapp]

Welcome to EP.

what would you call a setup like that?

As far as I know there is no dedicated name for it. Maybe 'common ground' is the nearest expression, even if there is no connection to earth (what you refer to as ungrounded. 'Ground' is commonly used to denote the common potential in a circuit (also quite regularly called 0V).

What would be the effect?

Effect of what? Of being common or of being ungrounded?
Having a common potential (ground, 0V whatever you like to call it) is essential for two electrical circuits to work together. Energy (power, signals...) that goes from one circuit into the other needs a path to return to the source where it came from. Any electrical circuit neds to be able to form a closed circuit for current to flow. No closed circuit -> no current -> no power or information.

The thing I have in mind is an ungrounded photovoltaic system, with the 12V battery negative and the 60V PV negative on a common connection together at the charge controller

This is a regular setup. It wouldn't work without the common connection unless the charge controller is completely isolated (using e.g. an internal transformer for potential separation), which is quite uncommon.

 

[carilchasens]

I see nothing wrong with that. What is the battery used for? Are you going to charge it from the PV panel with a buck converter between the PV panel and the battery? That will work.

The 12 Volt battery bank is for 12V lights, radio. inverter. The common connection would be on a MPPT controller. (We are upgrading a system we acquired in a previous century) Thank you for mentioning the buck converter.. I googled it and am a lot less confused about how the setup could work..

 

[carilchasens]

Welcome to EP.


As far as I know there is no dedicated name for it. Maybe 'common ground' is the nearest expression, even if there is no connection to earth (what you refer to as ungrounded. 'Ground' is commonly used to denote the common potential in a circuit (also quite regularly called 0V).


This is a regular setup. It wouldn't work without the common connection unless the charge controller is completely isolated (using e.g. an internal transformer for potential separation), which is quite uncommon.

Harald, thanks..