Each PV panel has two wires used for power, one positive and one negative, that are used to connect it to the rest of the PV system. Two panels are connected to each other in series, for a total of two wires per every two panels. This amounts to 34 wires for the 34 PV panels on the LEAFHouse. An additional wire is attached to each panel for grounding purposes, but does not normally carry any electricity.
Running 34 small wires all the way to the inverter system is complicated and inefficient. Combining the 34 wires into fewer, larger wires decreases the power loss in the system because larger wires have less electrical resistance.
Circuit breakers in the PV circuits are also required by the National Electrical Code to provide protection against overcurrent. Breakers also provide a way to shut off part of the PV array to perform maintenence.
A PV combiner provides all of these features. Inside the combiners, the 34 smaller wires are grouped and combined into 3 separate PV panel circuits. These 3 circuits are arranged East to West to take advantage of the Sun's location throughout the day.
In the LEAFHouse, 2 OutBack Power Systems PSPV Combiners are used. Each combiner is capable of handling 2 circuits, so 2 combiners are necessary to handle the 3 circuits present in the LEAFHouse.
So instead of 34 wires, we now only have to deal with 7 larger wires (3 positive, 3 negative, and a ground. These larger wires travel to the FLEXware system where they are tied into the Charge Controllers.
For more information about OutBack Power Systems products, please visit their website.