2 strings (3x panels) - which MPPT?

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owen-a asked Mar 19, '24

2 strings (3x panels) - which MPPT?

Hi all,

I have a hybrid install currently on my bar in my garden which consists of 3x 410w Sharp Monocrystalline panels facing in one direction (as seen by the image). The max I've seen them generate currently (given it's not the peak time in this time of the year) is about 1.01kW.

The max voltage I've seen (PV) is around 105v.

The max current I've seen (PV) is around: 9.52A

So around 1kW rounded.

Here is a photo:

The idea is to have another three panels on the other side of the roof giving me a total of 6. The issue i think is, the sun rises from the left side, and swings around to the right side where the 3 panels are currently. This for me is the most optimum place for these existing panels to generate as much power as I can during the late morning to late afternoon.

I'm quite new to Victron products, however I have currently applied to the DNO for exporting, so my plan is to have a Multiplus 2 3kW inverter that supplies power to the bar instead of my current Chinese inverter.

My question is, if I want two strings like I described, what's the best cost effective MPPT controller? And will I need two? Combined with ultimately the Multiplus 2 for providing power to the house in the future.

I currently have battery storage (2x 100Ah LiFePo4) batteries.

Any help is much appreciated!

Thanks,

Owen

offgrid ongrid

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Answer 1 · 2024-03-19T11:01:38Z

nickdb answered · Mar 19 at 11:01 AM

This is what the MPPT calculator is designed for:

https://www.victronenergy.com/mppt-calculator

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owen-a commented · Mar 19 at 11:57 AM

So from what I understand, if I buy two of these devices and link them together, combined with a GX for monitoring, and the GX into the Multiplus 2, I'll be sorted?

https://www.victronenergy.com/solar-charge-controllers/smartsolar-mppt-ve.can

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nickdb ♦♦ owen-a commented · Mar 19 at 12:38 PM

So you don't need big mppt's, the smaller ones the calculator will show you will be fine and they will be vedirect cabled to the GX. The manual has all the info for how to do this. Each mppt with its own string.

The calculator will check for the max voltage at cold temps, which is what must be sized for. I don't have your full specs but I would imagine the calculator will recommend 150/35 or 150/45 chargers.

Those are small arrays so should be straight forward.

The wiring unlimited guide also has good tips.

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owen-a nickdb ♦♦ commented · Mar 19 at 03:34 PM

Perfect. It seems like the voltage/current from the one I linked suits. It can handle more voltage and current than the string so that seems good.

Can the GX tell you how much power is being generated from both strings? Does it also tell you how much power is being exported to the grid?

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kevgermany ♦♦ owen-a commented · Mar 19 at 01:32 PM

Given the different orientation of the sets of panels you do need a second MPPT. Follow @nickdb comments about size.

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owen-a kevgermany ♦♦ commented · Mar 19 at 03:35 PM

I thought so. Thank you.

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Answer 2 · 2024-03-19T13:39:16Z

duivert answered · Mar 19 at 01:39 PM

you will need just 1 GX device either Cerbo GX or a Multiplus 2 GX,

in your case you can start with 2 mppt, (follow nickdb's advise) 1 cerbo gx, so you can add a normal multiplus 2 (without gx) later

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Answer 3 · 2024-03-19T13:48:53Z

billym417 answered · Mar 19 at 01:48 PM

? Where do I find the “wiring unlimited guide”?

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nickdb ♦♦ commented · Mar 19 at 02:01 PM

Type “victron wiring unlimited “ into your preferred search engine and viola!

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