# MPPT Controller Size

**URL:** <https://community.victronenergy.com/t/mppt-controller-size/50940>\
**Category:** DIY\
**Tags:** mppt\_controllers, rv, parallel, beginner\
**Created:** [30 December 2025 20:28 UTC](https://community.victronenergy.com/t/mppt-controller-size/50940 "2025-12-30T20:28:11Z")\
**Posts on this page:** 5\
**Page:** 2

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**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:** [4 January 2026 19:54 UTC](https://community.victronenergy.com/t/mppt-controller-size/50940/21 "2026-01-04T19:54:20Z")

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> [@bcborn](#):
>
> Short Circuit Current of 9.62 Amps

With 3 panels in series, the Isc is below the max input current of either controller.

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**Author:** ![bcborn](https://avatars.discourse-cdn.com/v4/letter/b/96bed5/32.png) [@bcborn](https://community.victronenergy.com/u/bcborn)\
**Post date:** [4 January 2026 20:07 UTC](https://community.victronenergy.com/t/mppt-controller-size/50940/22 "2026-01-04T20:07:04Z")

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For my 75/15 MPPT Controller for the solar on the side port (200 Amp Suitcase), Is a 15amp Circuit Breaker on both sides (Bat/PV) adequate here?

Short Circuit Current of my 200 watt suitcase is 11.72A

The Max Continuous load for the Victron 75/15 is 15 amps, the short circuit current is 15 amps.

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**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:** [4 January 2026 20:22 UTC](https://community.victronenergy.com/t/mppt-controller-size/50940/23 "2026-01-04T20:22:16Z")

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PV side breaker 15 or 16A.  
output side breaker: you want some headroom, as 15A through a 15 A breaker or fuse for 4 hours will cause significant heating. Standard formula is 1.25_Ic\<Ib\<1.5_Ic. Where Ib is breaker rating, and Ic is circuit current, in this case 15A, so you want a 20A breaker.  
Note: Isc for a PV module is a different concept than short circuit or max load current elsewhere i.e. on a battery powered circuit.  
PV modules are inherently current limited - so the max current they can supply into a short circuit is limited. MPPT controllers also specify the MAX input circuit current - so the module Isc must be less than that.  
Battery circuits are only limited by the battery voltage and circuit resistance, so if the output (Battery side) of an MPPT controller was accidentally shorted, the current is huge, potentially 100’s of amps.

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**Author:** ![bcborn](https://avatars.discourse-cdn.com/v4/letter/b/96bed5/32.png) [@bcborn](https://community.victronenergy.com/u/bcborn)\
**Post date:** [4 January 2026 23:01 UTC](https://community.victronenergy.com/t/mppt-controller-size/50940/24 "2026-01-04T23:01:02Z")

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Thanks Mike for the advice

To reiterate

Victron MPPT 100/50 for the 600 watts wired in series of roof panels.  
15Amp Circuit Breaker/Fuse on the PV side of Controller  
60Amp Circuit Breaker/Fuse on the Bat Side of Controller

75/15 for the 200 watt Renogy portable suitcase. (FYI, The portable suit case is 2 x 100 wired in Parallel). The onboard Renogy Controller was removed for direct connection tion to the SAE Solar on the side port which connects to the Victron 75/15 MPPT PV Terminals.  
15Amp Circuit Breaker/Fuse on the PV Side of Controller  
20Amp Circuit Breaker/Fuse on the Bat Side of Controller

Thanks

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<div class="post-metadata">

**Author:** ![bcborn](https://avatars.discourse-cdn.com/v4/letter/b/96bed5/32.png) [@bcborn](https://community.victronenergy.com/u/bcborn)\
**Post date:** [19 August 2026 18:19 UTC](https://community.victronenergy.com/t/mppt-controller-size/50940/25 "2026-08-19T18:19:29Z")

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> [@bcborn](#):
>
> To reiterate
> 
> Victron MPPT 100/50 for the 600 watts wired in series of roof panels.  
> 15Amp Circuit Breaker/Fuse on the PV side of Controller  
> 60Amp Circuit Breaker/Fuse on the Bat Side of Controller

I experienced Random tripping of the 60Amp Circuit Breaker/Fuse on the Battery Side of the Controller.

I cannot figure out when and why it Randomly trips. I just got back from a 3000km trip and it had tripped twice. Unsure if it could be from heat in the trailers passthru to where it is mounted. Unsure if the 100amps from the Victron DC/DC Charger (Controller and DC/DC Charger share same 6g wire to battery) have any impact.

Read some have had tripping issues with the same type of Circuit Breaker/Fuse being used here (inline Stereo Type).

One other issue I’m having with the Victron 100/50 MPPT Controller. At 13.13 (approx) Battery Voltage and 50+ Volts (Panels in Series) the App reports Bulk Charging yet output 0 (Zero) Watts middle of the day.

Absorption set to 14.4 and Float to 13.4

Thoughts

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