Hi and new year 2025 greetings to all
My sailing boat is equipped with Multiplus 3000/120/12 - 4x100Ah 12v lithium batteries, Color Control GX, BMV-712, Digital Multi Control, Generator, engine Alternator and shore power.
I’m adding solar panels to this installation and have the following questions, which I hope some of you can guide me in the right direction.
Can I use 24V panels in my 12v system as 24v panels have higher efficiency
If yes - Should I install the 2 panels (215/24) in serial (24v) or parallel (48v)?
Will the Victron MPPT change the current til 14,4 volt from the higher 24/48v?
Should the connection from MPPT to 12v system go to the two busbar’s or to the 12v output on the Multiplus?
The MPPT is connected to the CCGX with Ve direct. When connected to shore power or generator, what will prevent the MPPT to overload the lithium batteries and what will determinate where the power comes from?
I know it is many questions, but thanks in advance anyway
Kind regards from DK/Lasse
Hi Lasse, welcome to the forum.
The Victron MPPT’s need about +5V more than the battery voltage, to start charging. When you use 24V panels, they might give about 18-20V with average daylight intensity, what is enough to get a Victron MPPT working.
Regarding the difference between serial or parallel, this does not matter for the MPPT, the harvested power from the solar panels will always be converted to the correct charge voltage. The only thing you need to check, is the MPPT maximum input solar voltage. Victron has a calculation tool on their website, to determine wich MPPT model suites your solar setup best.
When you put the solar panels in series, you will get the highest voltage, what makes the MPPT also work with less daylight. But when one of the solar panels gets (partailly) shadow, the serial connection power will be pulled down. When shadow is an issue, then parallel is the better option.
The MPPT output can be connected on the main busbars of the setup, with it’s own fuse. On this busbar all 12V wiring is connected with their own fuse. Just set the bulk, absorb, and float charge of the MPPT, Multiplus, etc. on the same voltages, so that they are in balance towards charging the battery.
When the MPPT, Multiplus, etc. are in a Ve network, they will, let’s say, “talk” with each other, making that all Victron hardware is working propely together.
Thanks Theo for a clear and useful answer and you time to create it.
kind regard
Lasse
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