# MPPT-Calculator Issue

**URL:** <https://community.victronenergy.com/t/mppt-calculator-issue/50716>\
**Category:** Q&A and troubleshooting\
**Tags:** expert, mppt\_controllers\
**Created:** [26 December 2025 17:03 UTC](https://community.victronenergy.com/t/mppt-calculator-issue/50716 "2025-12-26T17:03:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![kultex](https://avatars.discourse-cdn.com/v4/letter/k/898d66/32.png) [@kultex](https://community.victronenergy.com/u/kultex)\
**Post date:** [26 December 2025 17:03 UTC](https://community.victronenergy.com/t/mppt-calculator-issue/50716/1 "2025-12-26T17:03:36Z")

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I have a 13 years installation with 20 Heckert NeMo P210 and wanted to use the rest of my roof, where was still space for 2 panels, because I bought a Multiplus II 5000 and a Pytes V5 Battery - so I was searching for 2 panels, which are supported by the Smartsolar 100/20.

And because I just need 2 panels, they must be availaible in the neigbourhood…..

I found Trina TSM-500NEG18R.28 Vertex S+ for 160 € incl. transport to my house for the 2 panels….

> **[Trina\_Vertex\_S\_TSM-500NEG18R.28.pdf](https://cdn.shopify.com/s/files/1/0556/0539/5791/files/Trina_Vertex_S_TSM-500NEG18R.28.pdf?v=1728029727)**
>
> 296.51 KB

When I entered them into the MPPT-Calculator - there is just reporting to increase the input voltage. I was calculting and thought, they must fit - the Trinas deliver around 80V open-circuit voltage in series. At -10°C, the voltage is below 100V and is suitable. Below 20A max. short-circuit current, it is also suitable.

And thanks god - I bought them - they are working perfect - maybe you should correct the MPPT-Calculator

22.11.2025 (partly sunny)

 ![Smartsolar-22.11.2025](https://europe1.discourse-cdn.com/victron/original/3X/0/9/09e21a8f4df897d2e636621c948f7be9a6226121.jpeg)

25.12.2025 totally sunny - but shadow after 13:30

 ![Smartsolar-25-12](https://europe1.discourse-cdn.com/victron/original/3X/1/c/1c92b9937f798415829ce3481f193849aaa71b73.jpeg)

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<div class="post-metadata">

**Author:** ![kultex](https://avatars.discourse-cdn.com/v4/letter/k/898d66/32.png) [@kultex](https://community.victronenergy.com/u/kultex)\
**Post date:** [26 December 2025 19:03 UTC](https://community.victronenergy.com/t/mppt-calculator-issue/50716/2 "2025-12-26T19:03:40Z")

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Ok - I think the MPPT-Calculator got better in the meantime - now I just change the Max Temp from 60° to 59° and the Smartsolar 100/20 appears

In September, when I was looking, it was very strange when I changed the values - maybe I will find a screenshot from those days…

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<div class="post-metadata">

**Author:** ![kultex](https://avatars.discourse-cdn.com/v4/letter/k/898d66/32.png) [@kultex](https://community.victronenergy.com/u/kultex)\
**Post date:** [27 December 2025 08:38 UTC](https://community.victronenergy.com/t/mppt-calculator-issue/50716/3 "2025-12-27T08:38:31Z")

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Just for dokumentation, if somebody is interested…. I found a Longi panel that fitted and changed the values from the Trina to the exact values from the Longi and the Easysolar appeared….

 ![Trina-advanced-2](https://europe1.discourse-cdn.com/victron/original/3X/3/f/3fbdb25a30ab3f5c53c5212bb7ec8ee4da153aa2.png)