# Wiring unlimited DC grounding - contradiction **URL:** \ **Category:** DIY\ **Tags:** victron\_community, mppt\_controllers, diy\ **Created:** [31 January 2025 05:57 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562 "2025-01-31T05:57:33Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 05:57 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/1 "2025-01-31T05:57:33Z")
In chapter 7.7 of Wiring Unlimited there is an apparent contradiction between the text of the first paragraph and the accompanying diagram. See the highlighted sections in the image below: ![image](https://europe1.discourse-cdn.com/victron/original/2X/8/8f92b80fd07da410628b3a11cabe8872ec67afa6.png) The text appears to indicate that there should be no grounding of the MPPT DC negative, however the diagram clearly shows the MPPT DC negative tied to ground through the common battery negative. Could we please have a definitive answer to clear up this apparent contradiction. ---
**Author:** ![nesswill](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/nesswill/32/125_2.png) [@nesswill](https://community.victronenergy.com/u/nesswill)\ **Post date:** [31 January 2025 06:44 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/2 "2025-01-31T06:44:46Z")
Hi Ken and welcome to the community, you are getting confused, look closely… It’s saying not to ground the **PV negative** , not the MPPT DC negative See here \>\> [4. Installation (victronenergy.com)](https://www.victronenergy.com/media/pg/Manual_SmartSolar_MPPT_150-60_up_to_250-70/en/installation.html) **4.6. Electrical connections** ---
**Author:** ![grua](https://avatars.discourse-cdn.com/v4/letter/g/ec9cab/32.png) [@grua](https://community.victronenergy.com/u/grua)\ **Post date:** [31 January 2025 07:19 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/3 "2025-01-31T07:19:56Z")
PV and battery. Two different things! But most people dont’t ground the battery minus. ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 07:32 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/4 "2025-01-31T07:32:48Z")
Th text states the following: “The PV negative input of the MPPT is not isolated from the negative output”, this leads me to believe there is a current path between PV input and MPPT output. Then the diagram shows a direct MPPT to battery negative connection which is then grounded. Hope that clears up the contradiction I see. ---
**Author:** ![alexpescaru](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/alexpescaru/32/270_2.png) [@alexpescaru](https://community.victronenergy.com/u/alexpescaru)\ **Post date:** [31 January 2025 07:34 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/5 "2025-01-31T07:34:08Z")
PV negative input is NOT isolated from negative output. Hence, PV negative = MPPT negative output. MPPT negative output = Battery negative. In the picture the battery negative is grounded, hence the PV negative will be grounded. A contradiction, so the OP is right… LE: Ken beat me to it… 😄 ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 07:35 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/6 "2025-01-31T07:35:21Z")
If you read the text along with the diagram you will see there is a connection between the PV, battery and ground, this is the source of my confusion. ---
**Author:** ![pwfarnell](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/pwfarnell/32/2341_2.png) [@pwfarnell](https://community.victronenergy.com/u/pwfarnell)\ **Post date:** [31 January 2025 07:43 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/7 "2025-01-31T07:43:29Z")
Given that the battery is connected to ground you have one connection. The text states do not ground the solar panel array. If you also ground the solar array positive or negative then you will have 2 ground points at slightly different voltages so you will get ground currents. What the whole section is saying is only have one grounding point for the DC negative. In steel hulled boats for instance as this is talking off grid, you must avoid ground currents at risk of corrosion of the hull. ---
**Author:** ![nesswill](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/nesswill/32/125_2.png) [@nesswill](https://community.victronenergy.com/u/nesswill)\ **Post date:** [31 January 2025 07:54 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/8 "2025-01-31T07:54:18Z")
Hi if you have two ground connections you create a parallel path for normal current to flow, i.e. a ground loop (ground loops are bad news and often hard to find). But I understand why people get confused. So what @pwfarnell says… ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 07:57 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/9 "2025-01-31T07:57:40Z")
The text is about not grounding the POSITIVE or NEGATIVE of the PV array. This is not the case as indicated in the diagram. Grounding of array, if you are referring to the array frame in your reference to “solar panel array” is a separate discussion. ---
**Author:** ![pwfarnell](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/pwfarnell/32/2341_2.png) [@pwfarnell](https://community.victronenergy.com/u/pwfarnell)\ **Post date:** [31 January 2025 07:59 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/10 "2025-01-31T07:59:08Z")
Yes and my reply applies to this, although it was not strictly stated, i have edited. ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 08:00 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/11 "2025-01-31T08:00:33Z")
I am referring to the diagram as it is, there is a clear path from PV negative to ground which is contradicted in the text. ---
**Author:** ![nesswill](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/nesswill/32/125_2.png) [@nesswill](https://community.victronenergy.com/u/nesswill)\ **Post date:** [31 January 2025 08:04 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/12 "2025-01-31T08:04:28Z")
Have a read of this… [Grounding Basics 3 - Solar Panel Grounding.pdf](https://community.victronenergy.com/uploads/short-url/pxideLQd9Lf7Sqep8CQPoQXuSNg.pdf) (375.9 KB) ---
**Author:** ![pwfarnell](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/pwfarnell/32/2341_2.png) [@pwfarnell](https://community.victronenergy.com/u/pwfarnell)\ **Post date:** [31 January 2025 08:07 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/13 "2025-01-31T08:07:17Z")
I am afraid that you can not take a small extract out of context, read the whole section. It is not saying that the PV negative must not get to ground at some point in the system, but that it must not get to ground directly on its own. That whole section says to ground the negative at a single point. There is nothing wrong with the diagram, it is your comprehension of the whole section. ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [31 January 2025 08:07 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/14 "2025-01-31T08:07:19Z")
The mppt frame is connected to ground. Not the actual pv and battery conductors. There are little screws on the casing for it. Same as the inverter itself. Earth connection is not grounding. ---
**Author:** ![nesswill](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/nesswill/32/125_2.png) [@nesswill](https://community.victronenergy.com/u/nesswill)\ **Post date:** [31 January 2025 08:22 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/15 "2025-01-31T08:22:11Z")
> [@lxonline](#): > > Earth connection is not grounding. What @lxonline says this is a **very important** point People reading this must understand the difference. ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 08:31 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/16 "2025-01-31T08:31:31Z")
Maybe I have not asked the question clearly enough and no I am not taking anything in isolation but these two sentences are explicit: Do not ground the positive or negative of the PV array. and The PV negative input of the MPPT is not isolated from the negative output. Then the diagram goes on to show based on the two sentences above, what amounts to a direct connection to the PV negative. Edit: Deleted incorrect interpretation of text. ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 09:10 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/17 "2025-01-31T09:10:11Z")
Thank you @pwfarnell That clears it up, ignore my previous post. 😊 It is saying, do not ground Negative of the panels upstream of the MPPT when the grounding will occur after the MPPT at the battery terminals. Maybe this very explicit sentence needs a litle clarification - "Do not ground the positive or negative of the PV array. " seems to imply no grounding whatsoever of the positive or negative PV outputs which is clearly contradicted in the diagram. The wording could be clarified for instance add that "Direct connection of PV positive or negative must not be done at the PV array. I fully understand the issues of creating multiple paths to ground. ---
**Author:** ![alexpescaru](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/alexpescaru/32/270_2.png) [@alexpescaru](https://community.victronenergy.com/u/alexpescaru)\ **Post date:** [31 January 2025 09:32 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/18 "2025-01-31T09:32:23Z")
Also to be clear that PV-IN negative is the same with the DC-OUT negative. ![1](https://europe1.discourse-cdn.com/victron/original/2X/8/8df4a4a20cb692027d6e5fa4d5ddbf9036197149.jpeg) ---
**Author:** ![kejba](https://avatars.discourse-cdn.com/v4/letter/k/d9b06d/32.png) [@kejba](https://community.victronenergy.com/u/kejba)\ **Post date:** [31 January 2025 09:33 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/19 "2025-01-31T09:33:34Z")
Thanks Dave between you and @pwfarnell my confusion has been clarified. ---
**Author:** ![nesswill](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/nesswill/32/125_2.png) [@nesswill](https://community.victronenergy.com/u/nesswill)\ **Post date:** [31 January 2025 09:37 UTC](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562/20 "2025-01-31T09:37:13Z")
You’re welcome. It’s good too hear you understand and good luck with what ever project you undertake and remember we are all here to help. 👍 [Next page](https://community.victronenergy.com/t/wiring-unlimited-dc-grounding-contradiction/20562.md?page=2)