Connecting Batteries to Inverter

The batteries must be wired to each other and to the inverter. Because the voltages are so low, 6 to 48 volts, the currents might be very large. To carry these large currents without dangerous heating requires very large wires. Most of us to do not commonly work with such large wire, but anyone who owns a car uses it nearly every day: the battery cables on your automobile are precisely the type and size of wire we will use in our off-grid power system.

Larger wires are able to carry more electrical current with less resistance. It is the resistance that causes the heating of wires and the loss of (valuable) electrical energy. We can reduce these losses by using larger wires. Of course, larger wires cost larger sums of money, so we will want to balance the amount of money we spend on the benefit we receive.

The table provides a common recomendation for battery wire size based on the total current being carried. Larger wires can be used, but the benefit in doing so will generally be less than the increase in cost. These wires are available at any well stocked automotive parts store just be asking for battery cables of the gauge indicated. Many stores will only stock a limited range of sizes, number 2 and 4 being common, but larger stores should have the 0 and 00 gauge as well.

....table here.....

The larger wires can be difficult to handle because they are relatively stiff. If this is a problem, the "welding wire" can be used instead. This is stranded, rather than solid core, so it is much more easily bent. It is also much more expensive.