I am setting up a solar system in a vehicle. I have 400W solar panels, a 12V battery bank, and a 2000W inverter. I've looked at the manuals and read online to figure out the wiring diagram below.

However I'm still not sure if I can ground the inverter and the battery separately (this would be convenient since they are 10 feet away from each other).

Or if I need to connect them to each other and ground just one device, which am I supposed to ground, the battery or the inverter?

Feel free to point out any other problems with my diagram, I'm just here so I don't set myself on fire.

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    \$\begingroup\$ What is the make and model of inverter? Can you link to the installation instructions? Also, I notice that you show a 40A fuse in series with the inverter on the DC side. However, if the inverter is putting out 2000 W, the input current will probably be over 200 A at 12V. I would like to read the inverter installation instructions, but probably you need to ground the battery to chassis near the battery (DC ground) and ground the inverter to the chassis near the inverter (AC protective earth ground). But if you have a shore power input on the inverter, AC ground is more complicated. \$\endgroup\$ – mkeith Jun 25 '17 at 18:50
  • \$\begingroup\$ @mkeith Here is the inverter: Aims 2000 Watt 12V Pure Sine Wave Inverter invertersrus.com/product/aims-pwrig200012120s and here is the installation instructions invertersrus.com/wp-content/uploads/2016/03/… It says to connect the inverter directly to the battery and doesn't show any grounds. There is no shore power. \$\endgroup\$ – Amanda Jun 26 '17 at 17:40
  • \$\begingroup\$ It is important to have a very low resistance path between battery negative terminal and inverter negative terminal. If it is possible to bond them both to the chassis very securely, and verify that the resulting resistance is very low, then you can do that. To be safe, you should probably run a heavy gauge cable between them. That way you can be sure the resistance is low. You still need to have a good connection to chassis ground because, as others have said, the chassis is probably being used for ground return currents in your system. I would make that connection near the battery. \$\endgroup\$ – mkeith Jun 27 '17 at 2:56
  • \$\begingroup\$ As far as AC grounding goes, this is really a tricky subject, and I am disappointing in the installation manual because it pretty much bypasses it. Are you going to use the outlet on the inverter, or are you going to have an AC circuit breaker panel and AC wiring inside the vehicle? \$\endgroup\$ – mkeith Jun 27 '17 at 2:58
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    \$\begingroup\$ I think the chassis GND should make use of a metal stud permanently attached to the chassis, and a ring terminal crimped onto the cable. A nut would secure the ring terminal on the chassis stud. \$\endgroup\$ – mkeith Aug 24 '17 at 4:10

You should always follow the wiring recommendations supplied by the inverter manufacturer. Absent those recommendations, I would proceed as follows:

Treat the battery as your "Star" point.

The cables from both the positive and negative leads of the inverter should go directly to the battery. These need to be thick and as short as possible. Also be sure to include adequate over-current protection in the inverter Positive lead.

The leads from your charging source(s) should also terminate at the battery. Again: include adequate over-current protection.

If you require a system Earth ground, that also connects directly to the battery Negative terminal.

Under no circumstances should you attempt to use the metal chassis as a current-carrying conductor.

Note that when I say "Battery Terminal", this is often a buss-bar arrangement with many connection points. These are located very near to the battery bank.

Common buss-bar tie points that I use derive from the Telcom industry and are 3/8" thick copper bars about 3" wide by as long as necessary with numerous 1/4-20 and/or 5/16-18 tapped holes.

Finally, note that many inexpensive consumer-grade AC inverters will NOT allow the Neutral output conductor to be grounded. That is because the internal DC-DC converter is not isolated from the output stage. In these inexpensive inverters, the Line & Neutral terminals alternate in polarity between the DC ground line and the high-voltage positive output of the internal DC-DC converter.

Attempting to ground the Neutral output conductor results in either blown fuses or blown output switching devices.

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  • \$\begingroup\$ "Under no circumstances should you attempt to use the metal chassis as a current-carrying conductor." This is an odd statement as every other standard component on a car does just that. Granted the current demanded here is high it is not as high as the starter motor current which usually also uses the chassis. \$\endgroup\$ – KalleMP Nov 28 '18 at 7:58
  • \$\begingroup\$ @KalleMP We talk about PV setup and inverter. This topic is very different from a regular car installation. If you have separate wire to send current instead of using chassis will save you a lot of trouble in the future, some charge controllers and inverters devices simply don't have the isolated lines. \$\endgroup\$ – NeverEndingQueue May 16 at 11:24

The grounds for the DC circuits will be best using a good connection to the chassis with short cables. Note that I said for the DC circuit, as that seems to be what you are asking about. I do not have the knowledge level to comfortably tell you where or how to ground anything on the AC side of the system.

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