Posted by Peter Kennedy on 2/15/2019 to System Integration
This post shows a wiring diagram prepared by Victron Energy showing in detail how some of their products connect together. This is a very detailed drawing and so it is a particularly useful tool for a discussion about how to wire a system. I never have the time to do drawings that are this detailed. There are many ways to wire a system, and this is just one way, every installation is different and my aim here is to discuss the choices that were made in this particular system.
This project uses a 24 volt battery bank made up of individual 12 volt AGM Super Cycle batteries in a series parallel configuration. Notice how the positive connection is taken from one end of the bank and the negative from the other so that the load is evenly distributed between all the batteries.
Main Circuit Protection
There is an ANL fuse placed close to the battery. This type of fuse offers a high interrupt capacity and so meets the ABYC requirements. It allows subsequent fuses and circuit breakers in the system to have a lower interrupt capacity. In the ABYC standards this primary circuit protection should be within 7" of the battery, or if the wire is sheathed or in conduit it may be up to 40" from the battery.
This drawing has two battery switches, one for the inverter charger and one for everything else. A battery switch is required but having two like this is not a requirement. In this drawing three items are connected in such a way as to bypass the battery switch. The solar panels are a charging source and so are permitted to bypass the switch. The power supply to the BMV Battery Monitor is allowed to bypass the battery switch because it always needs to be connected. The power supply to the Color Control GX isnt really essential because the system can work without it.
Main DC Distribution
The drawing shows a series of Mega Fuses going to individual loads. One could also use ANL or Terminal Fuses which have a wider range of sizes. ANL fuses have a window to see if the fuse is blown or not, Terminal Fuses are very compact for tight spaces. I would suggest that the main power supply to the DC panel be protected by a circuit breaker and not a fuse. If the fuse blows you may find yourself in the dark searching for a replacement.
The drawing shows doubled up cables supplying the MultiPlus inverter charger. The high DC currents can cause voltage drop and doubling up the cables is a way to reduce this without ending up with monster cables. Even though the cables are doubled up each has its own fuse, they are showing 150 Amps for each.
The negative busbar is preceded by the shunt for the BMV Battery Monitor. The shunt needs to be the first thing in line on the negative connection from the battery. They have shown the busbar connected on top of the shunt but a more common arrangement would be to have the two adjacent to each other. The temperature sense wire seen near the shunt is not a current carrying conductor and so is allowed to connect direct to the battery.
Apart from the battery cables already mentioned the MultiPlus has one incoming AC cable and two outgoing AC cables. Each of the outputs is taken to a different part of the AC distribution panel. One leg is available only when shore or generator is connected, the other leg is also available in invert mode. This means that it is possible to connect heavy loads like air conditioning in a way that prevents them being run on inverter power. There is a VE Bus data cable that runs to the Color Control GX
Shore Power and Generator
Both the incoming shore power and the generator have a circuit breaker. Thsy have shown these together but it would be more likely to have them apart since each should be as near as possible to where the power comes from. A transfer switch then selects between shore and generator power. A note on the drawing draws attention to the need for a galvanic isolator or isolation transformer to avoid corrosion issues.
This system has a Smart Solar MPPT 100/30 charge controller with an allowed maximum input voltage of 100 Volts and a maximum output current of 30 Amps. When used in a 24 volt system it can support up to 700 Watts of panels. The charge controller is programmable via the Bluetooth Link. It is connected to the Color Control GX using a VE Direct cable so that it will show up on the main system screen. In this drawing they have shown a circuit breaker between the charge controller and the solar panels as well as a circuit breaker where the charge controller connects to the batteries.
The Battery Monitor shown here is the BMV 712. This is an amp hour meter that can show the state of charge of the battery as well as amps going in or out, voltage, and time to go. You can connect to it using the Victron Connect App available for iPhone or Android, PC or Mac. The shunt beside the battery negative terminal does all the measuring and the shunt connects to the meter with a telephone cord style cable. The meter connects to the Color Control GX using a VE Direct data cable.
Color Control GX
The Color Control GX is an optional display that can show all the Victron system data in one screen. It can be used to turn the MultiPlus on and off or set its charging current, it displays the state of charge of the battery and shows the solar output. The more Victron equipment you have on board the more valuable this becomes. It can connect to the internet with a wifi dongle or a hardwired connection. Once online the system can be monitored remotely using Victron's free VRM Portal.
The notes at the bottom of the drawing talk about wires sizes for AC and DC wires. You might like to refer to the Ampacity Tables to see a comparison between AWG wire sizes and the European sizes they refer to at Victron
I have written an extensive collection of Blog Posts about the MultiPlus and Quattro Inverter Chargers.