What PV is Best for my Victron 100/50 with 120AH AGM?

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peterb381 asked Mar 14, '21

What PV is Best for my Victron 100/50 with 120AH AGM?

Hey guys, really after some help, as I’m doing circles mostly in my mind.

I have a Victron 100/50 MPPT with a 12V Fullriver 120AH battery

…without any input, I’ve calculated it would take 1.2days to completely flatten from my usage.

My goal is obviously to recharge the battery in the most efficient way possible, with size of panels being ‘somewhat of an issue’ – as in, I would prefer smaller panels – but if it makes sense to do so, I will get creative with room to accommodate bigger panels.

Option 1: 3 x Renogy 100 Watt 12 Volt Mono Solar Panel(Compact Design)

Solar Cell Type: Monocrystalline Cable outputs: 12AWG

IP65 Rated waterproof junction box IP67 Rated waterproof MC4 connectors

Maximum Power: 100W Maximum System Voltage: 600V DC (UL)

Optimum Operating Voltage (Vmp): 17.9V Open-Circuit Voltage (Voc): 21.6V

Optimum Operating Current (Imp): 5.72A Short-Circuit Current (Isc): 6.24A

Weight: 6.5 kg Dimensions: 1074 x 498 x 35mm

Number of Diodes: 1 Diode(s) Diode Type: 15SQ045

*I may possibly go 4 panels, and these would fold up nicely as opposed two opt.2

Option 2: 2 x Renogy 160 Watt 12 Volt Monocrystalline Solar Panel

Solar Cell Type: Monocrystalline

Max Power at STC: 160W

Open Circuit Voltage: 22.9V Short Circuit Current: 8.37A

Opitmum Operating Voltage: 20.2V Optimum Operating Current: 7.92A

Operating Temperature: -40℃ to 90℃ Product Dimensions: 130.3 x 65.8 x 3.5 cm

Product Weight: 12 kg

…in the forum, I’ve seen people comment for option 1 that 21.6v is a bit on the low side considering +5v for MPPT to work?

So, my thoughts for Option 1 [if I went 4 panels] would be two serials in parallel? But with all of the PV world being out of my league, I’d really like some guidance – for instance, do MPPTs prefer more voltage and less amps, or more amps less voltage (or don't they care), and it comes down to sun harvesting approach i.e. I’ve heard before higher voltage panels are better for collecting earlier and running later? Anyhow, would really appreciate anyone shedding some light ;) on the best approach. Many thanks in advance, Peter

MPPT Controllers solar sizing

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Answer 1 · 2021-03-14T08:11:41Z

seb71 answered · Mar 14, 2021 at 08:11 AM

without any input, I’ve calculated it would take 1.2days to completely flatten from my usage.

Don't completely discharge any lead-acid battery. You can safely use 30% of the capacity and up to 50% occasionally.

Regarding the panels: if all are installed on the same surface (same angle and same azimuth) and if there are no shading issues, the best option is to wire panels in series (taking care to stay under the solar charger maximum voltage limit, even at low temperatures).

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peterb381 commented · Mar 14, 2021 at 10:52 AM

Indeed! Thanks a lot for that, I really appreciate it - in that case, the form of the 100W panels will suit me just fine. If you don't mind sparing another moment of your time, I started another Question (as it seemed quite distinct) that I would love your critique/consideration; basically, my final system layout - and whether you'd give it a 'Yay, or Nay' - at: https://community.victronenergy.com/questions/81140/victron-10050-inverter-wiring-setup-help.html

Thanks again @Seb71 - very helpful!

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