Solar panel wiring

Silvercloud

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I have a small Victron charger that keeps my batteries charged when conected to shore power and want to put some solar panels on the roof.
I understand that I need an MPPT controller for the panels but can this be used in conjuction with my current charger or do I have to change everything and how is the wiring conected?
 

vas

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I have a small Victron charger that keeps my batteries charged when conected to shore power and want to put some solar panels on the roof.
I understand that I need an MPPT controller for the panels but can this be used in conjuction with my current charger or do I have to change everything and how is the wiring conected?
just add the mppt and the panels, feeding the batteries.
System will sort itself out according to needs.
I have 600W solar 60A alternator and 70A multiplus inverter charger. Occasionally all three are on, like motoring during daytime and running the generator for the watermaker, all's good, no worries

V.
 

longjohnsilver

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Exactly what vas says. Just pick decent sized cable to avoid voltage drop between panel and controller and batteries.
 

Hurricane

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Yep - agree all this
Just parallel up the output of the MPPT to the batteries.
I have used MCB switches/fuses in all legs (between the panels and the MPPT and between the MPPT and the batteries).

For wire sizing, this is a good calculator where you can determine the losses against different wire sizes.
DC Cable Sizing Tool - Use The Correct Sized Cables - Free Calculator
 

vas

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I have used MCB switches/fuses in all legs (between the panels and the MPPT and between the MPPT and the batteries).
out of curiosity, have they ever tripped Mike?
I've not installed any fuses/breakers in my setup, just straight cables to the MPPT. There's a breaker from MPPT to the batteries though.

V.
 

Hurricane

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out of curiosity, have they ever tripped Mike?
I've not installed any fuses/breakers in my setup, just straight cables to the MPPT. There's a breaker from MPPT to the batteries though.

V.
Nop - never tripped.
I have MCBs above the ceiling where the wires come through from the panels, MCBs in the engine room next to the battery bank and MCBs either side of the MPPT controller which is located behind our dinette seats in on the main deck.
You have to remember that you can't switch solar off without covering the panels with a blanket.
Mine are wired in series thus increasing the voltage and reducing the wire size.
And the batteries are 24 volt so that keeps the wire size down on the battery side of the MPPT.

Another point to consider.
If you are using Victron MPPTs, you need the solar panel voltage to be 5v above the battery voltage before the MPPT will switch on.
Mine, being in series, are way above that voltage but with a single panel you could fall into that trap.
 

vas

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Thanks Mike,

atm I'm fine as I have the special quick fit connectors visible under the hardtop (until I manage to fit the lining there!) so easy to isolate the panels by pulling a plug.
Mine are also in series for the same reason 2X300W with max Vout 46 or so V, so typically on a summer day I get 80V+ output, so no probs with the Victron MPPT 30A/100V
I'll keep it in mind and fit an MCBs on the MPPT input side in the winter!

cheers

V.
 
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