What Size Cable For 12v Solar Panel

Choosing the right wire sizes in your PV system is important for both performance and safety reasons. If the wires are undersized, there will be a pregnant voltage driblet in the wires resulting in excess power loss. In addition, if the wires are undersized, there is a take chances that the wires may heat up to the bespeak in which a burn may issue.

An electric wire carries current much like a water hose carries h2o. The larger the diameter of the water hose, the less resistance at that place is to water flow. Moreover, fifty-fifty with a large diameter hose, shorter hoses have better flow than longer hoses. Longer hoses have more resistance than shorter ones of the same bore. Electrical wires behave the same mode. If your electric wires (the copper gauge) are non large plenty or if the cablevision is longer than needed, then the resistance is higher resulting in less watts going to either your bombardment bank or the grid.

Copper wires are sized using the gauge scale: American Wire Gauge (AWG). The lower the judge number, the less resistance the wire has and therefore the higher electric current information technology can handle safely.
The chart below shows the capacity of various wire gauge sizes and their typical amp rating and application for both residential and solar applications.

Commercial solar PV panels over l watts or and so use 10 gauge (AWG) wires. This allows up to 30 amps of current to flow from a single console. If multiple panels are combined in parallel, and then a three to eight AWG "combiner" wire set is by and large needed to safely transfer the power to a charge controller or GTI.

The wires from the charge controller to the battery banking concern can by and large exist the same or larger gauge than the main set from the PV array. The exception (B*) is when the Charge Controller is of the type that tin operate a 12 or 24-volt bombardment bank fifty-fifty when the PV array is operating at higher voltages, such as 48 Vdc and larger. These Charge Controllers have big transformers that lower the voltage just in the process they increase the current going to the bombardment banking concern. Refer to the installation cloth for the charge controller y'all chose when selecting the correct wire size to use.

The wires between batteries in a battery bank tend to be the largest in the organization since they are used in conjunction with a power inverter that can at times need more current than that the PV system can supply on its ain. These same wires volition too have to behave current used simultaneously for charging and for power inversion. A typical battery bank wire size is one/0 or "one-ought."

Information technology is very of import to match the gauge and the wire lengths when combining batteries in a battery bank. If this is not done, and so the battery bank'southward life can be shortened and certain safety issues can result.

Wire run lengths

Normally the longest wire run is from the PV array to the location where the charge controller or GTI is located. Since all of the combined PV power flows through this wire ready, nosotros really need to choose information technology correctly to maximize functioning and to clinch condom.

The general rule-of-thumb is to stay below 2% Voltage drib on this run. Using the known resistance of the diverse wire gauges, it is possible to calculate the maximum length for a wire-pair for each wire gauge size.

Here is what that calculation looks like for a 12V PV system. You can double the length for a 24V organization, or quadruple it for a 48V system.

Example: Let'south take a 450-watt 12V organisation. At the Vmp of 18V, the maximum current is 450/xviii = 25 amps.

Looking at the wire capacity row, 10 AWG is the smallest guess wire that can condom be used. It is rated at 30 amps, college than the required 25 amps.

Adjacent, we look at the Array amps column, select row "25" and you can encounter that a 10 AWG wire pair just supports a cable length of 4.five feet! Going up to 4 AWG supports up to 18 feet to stay within the 2% loss criteria. This is not a lot of feet!

What this example illustrates is that we need to greatly appreciate the issue of cable length and its effect on losses. Many people have long cablevision runs and don't realize the touch this has on performance. Sometimes we have to tolerate peradventure a 4% loss rather than 2%, allowing us to double the length values shown in the table. Another option is to operate at a college voltage, such as 24V. This reduces the amps which reduces the wire losses.

The betoken is to design your system using a safe wire size merely also to be witting of the trade-off between system voltage, wire length, line losses, and costs. This is why planning should be done in detail before you rush out to buy things like cables.