In the home photovoltaic system, in order to reduce the power consumption, to protect people's lives and property, to extend the system life, the proposed use of copper cables. Aluminum is easier to catch fire than copper wire
In the electrical line, the risk of aluminum fire is much larger than the copper wire. In fact, the aluminum line of fire is not in the aluminum itself but is the connection of aluminum. Compared with the copper wire, the reason for the high risk of connecting the aluminum wire is as follows:
1) copper and aluminum joints prone to electrochemical corrosion
PV module, inverter and the grid switch between the use of cable connection, and components MC4 connector, photovoltaic inverter output terminals, and network switch terminals are made of copper, copper and aluminum can be directly connected , When the need to connect, to use copper and aluminum transition clamp, copper and aluminum transition joints and then connected. But the current copper and aluminum wiring head, are generally high-power, and home distributed photovoltaic are generally between 2-30KW, with 2.5-10mm copper wire, the market is very small copper and aluminum terminal. In fact the use of aluminum installation, are to save the cost, and will not go with copper and aluminum joints.
Copper and aluminum directly connected, it will form a chemical battery, which is due to the loss of aluminum as easy to become negative, copper is difficult to lose electrons become positive, so between the positive and negative to form a 1.69V electromotive force, and a Very small current through, corrosion of aluminum, that is, electrochemical corrosion. This will cause poor contact between copper and aluminum, contact resistance increases. When there is current through, will make the joint part of the temperature rise, and the temperature rise and more rapid joint corrosion, increased contact resistance, resulting in a vicious cycle, until burned.
2) The surface of the aluminum wire is easily oxidized in the air.
3) easily corrosion by hydrogen chloride.
4) High expansion coefficient.