# Mppt wont recognise other strings **URL:** \ **Category:** DIY\ **Tags:** multiplus-ii, easysolar\_all-in-one, beginner\ **Created:** [26 July 2025 05:20 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821 "2025-07-26T05:20:00Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Beenak47](https://avatars.discourse-cdn.com/v4/letter/b/f6c823/32.png) [@Beenak47](https://community.victronenergy.com/u/Beenak47)\ **Post date:** [26 July 2025 05:20 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/1 "2025-07-26T05:20:00Z")
My system is a Victron Easysolar 2 GX 48v/5000w/70a with Mppt 250/100 together with 3 strings of 5 x 440w panels with a Voc 37.4v & 13.4a. The Victron recognises the first string of 5 panels but goes to 0 when other strings are added. The polarity is correct & the voltages are near the same on all strings. I have switched off the Victron unit, disconnected the batteries & solar, but change. I haven’t tried the reset button as I am unsure of it. ---
**Author:** ![M\_Lange](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/m_lange/32/16_2.png) [@M\_Lange](https://community.victronenergy.com/u/M_Lange)\ **Post date:** [26 July 2025 05:44 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/2 "2025-07-26T05:44:07Z")
The MPPT doesn’t “recognize” PV panels, it only sees the PV voltage at it’s input. I’m pretty sure the problem is not the MPPT. Did you try to connect each sting one by one to the MPPT to see which string is working or not working? If the voltage goes to 0 with one string, try to reverse the polarity. ---
**Author:** ![Beenak47](https://avatars.discourse-cdn.com/v4/letter/b/f6c823/32.png) [@Beenak47](https://community.victronenergy.com/u/Beenak47)\ **Post date:** [26 July 2025 07:07 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/3 "2025-07-26T07:07:04Z")
Have tried each string separately and only 1 shows input on the Victron screen, the other 2 show zero watts. I have checked the polarity, its right. And the voltage is about the same on all of them. ---
**Author:** ![M\_Lange](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/m_lange/32/16_2.png) [@M\_Lange](https://community.victronenergy.com/u/M_Lange)\ **Post date:** [26 July 2025 07:13 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/4 "2025-07-26T07:13:40Z")
> [@Beenak47](#): > > 2 show zero watts or 0V ? 0V means PV is connected with wrong polarity. Did you try to connect the not working strings in reverse polarity to the MPPT? Add some pictures/screenshots. ---
**Author:** ![Beenak47](https://avatars.discourse-cdn.com/v4/letter/b/f6c823/32.png) [@Beenak47](https://community.victronenergy.com/u/Beenak47)\ **Post date:** [26 July 2025 07:36 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/5 "2025-07-26T07:36:30Z")
Will add pictures tomorrow. Thankyou ---
**Author:** ![Beenak47](https://avatars.discourse-cdn.com/v4/letter/b/f6c823/32.png) [@Beenak47](https://community.victronenergy.com/u/Beenak47)\ **Post date:** [27 July 2025 03:50 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/6 "2025-07-27T03:50:50Z")
Hi, ![20250727_105551](https://europe1.discourse-cdn.com/victron/original/3X/a/4/a4203e239c0b01f082a5e1456228f6d28c03865b.jpeg) ![20250727_112204](https://europe1.discourse-cdn.com/victron/original/3X/6/a/6acd8b91e4f3a46d6708e7bb2012ad8a8b1eb1ac.jpeg) ![20250727_130303](https://europe1.discourse-cdn.com/victron/original/3X/6/a/6acffdc8f708c6fbf6641ef8735e540c3939d8ba.jpeg) Have uploaded images. No1 photo - 1st string working ok No2 photo - 2nd string added - stops working No3 photo - voltage from 2nd string. ---
**Author:** ![water\_rat](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/water_rat/32/45_2.png) [@water\_rat](https://community.victronenergy.com/u/water_rat)\ **Post date:** [27 July 2025 04:26 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/7 "2025-07-27T04:26:13Z")
Are you sure the MC4 plugs are correctly polarized? ![MC4](https://europe1.discourse-cdn.com/victron/original/3X/8/3/83944311f62fb428ba639bea5a7a090abe3412fe.jpeg) The polarity markings are correct for cables on a solar panel. Pretty easy to mix things up with premade cables. ---
**Author:** ![Beenak47](https://avatars.discourse-cdn.com/v4/letter/b/f6c823/32.png) [@Beenak47](https://community.victronenergy.com/u/Beenak47)\ **Post date:** [27 July 2025 09:19 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/8 "2025-07-27T09:19:36Z")
Yes polarity is correct. Frustrating. Have checked panels, cables, Victron unit. When you junction all strings together with 3 to 1 mc4s thats where I think the problem lies. Test there & the voltage is good all the way thru to the Victron unit, then 2 mins later it all disappears & the voltage drops to 1-7 volts. ---
**Author:** ![MikeD](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/miked/32/1522_2.png) [@MikeD](https://community.victronenergy.com/u/MikeD)\ **Post date:** [28 July 2025 00:35 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/9 "2025-07-28T00:35:44Z")
> [@Beenak47](#): > > junction all strings together with 3 to 1 mc4s thats where I think the problem lies NEVER do this. These 3:1 or 2:1 parallel units Always cause problems. If you are paralleling 3 strings, then you need to use fuses for each string. Build a proper junction box with the fuse/ disconnectors for each string, then you can check the string voltages are correct before and after paralleling. ---
**Author:** ![Beenak47](https://avatars.discourse-cdn.com/v4/letter/b/f6c823/32.png) [@Beenak47](https://community.victronenergy.com/u/Beenak47)\ **Post date:** [29 July 2025 03:36 UTC](https://community.victronenergy.com/t/mppt-wont-recognise-other-strings/40821/10 "2025-07-29T03:36:11Z")
Turns out to be a cable issue. All correct & working now. Thanks for the help.