How to Connect Solar Batteries

To achieve proper charging conditions and have adequate power to operate your household appliances, your solar battery bank must be correctly connected. Batteries may be wired in two basic configurations, series and parallel. Series wiring means that the voltage will be cumulative and the amperage will stay the same. For parallel wiring, the amperage from all batteries will be cumulative, while the voltage remains the same. Care must always be taken when connecting your batteries. Poor or miswired connections can be extremely dangerous.

Things You'll Need

• Wire strippers/cutters
• No. 12 black insulated wire
• No. 12 red insulated wire
• 22 terminal crimp connectors
• Crimping tool
• Pliers
• Charge controller
• Multimeter

Instructions

Series Wiring

1. Connect negative (-) terminals to positive (+) terminals on all batteries for series wiring. For example, two 12-volt 75-amp batteries wired in series will produce an output power level of 24 volts at 75 amps, for a total of 900 watts.

2. Cut appropriate lengths of No. 12 wire for connecting to the next battery in the series. Leave an extra 2 to 3 inches of excess wire to accommodate for drip loops, termination repairs and ease of battery removal. If you have six batteries in series, you will need a total of 10 lengths of wire.

3. Strip 5/16-inch insulation from all precut lengths of wire on both ends. Depending on the crimp connector requirements or instructions, you may need to remove more or less insulation.

4. Crimp 20 battery terminal connectors onto both ends of the 10 lengths of pre-cut wire. Make sure to orient the connectors in the same manner to prevent twisting and improve aesthetics.

5. Interconnect five precut wires from the negative (-) terminal post to the positive (+) terminal post on the next battery in the bank.

6. Interconnect five pre-cut wires from the positive (+) terminal post to the negative (-) terminal post on the next battery in the bank

7. Test the battery power output using a multimeter. If you have six 12-volt 75-amp batteries, the power output should be 72 volts at 75 amps, for a total of 5400 watts. It is OK if the reading is slightly higher in any area.

Parallel Wiring

1. Connect all negative (-) battery terminals to one another using black No. 12 insulated wire. Connect all positive (+) battery terminals to one another using red No. 12 insulated wire. For example, two 12-volt 75-amp batteries wired in parallel will produce an output power level of 12 volts at 150 amps, for a total of 1800 watts.

2. Cut appropriate lengths of No. 12 wire for connecting to the next battery in parallel. Leave an extra 2 to 3 inches of excess wire to accommodate for drip loops, termination repairs and ease of battery removal. If you have six batteries in parallel, you will need a total of 10 lengths of wire, five black and five red.

3. Strip 5/16-inch insulation from all pre-cut lengths of wire on both ends. Depending on the crimp connector requirements or instructions, you may need to remove more or less insulation.

4. Crimp 20 battery terminal connectors onto both ends of all 10 lengths of pre-cut wire. Make sure to orient the connectors in the same manner to prevent twisting and improve aesthetics.

5. Interconnect five pre-cut black wires from the negative (-) terminal post to the negative (-) terminal post on the next battery in the bank.

6. Interconnect five pre-cut red wires from the positive (+) terminal post to the positive (+) terminal post on the next battery in the bank.

7. Use a multimeter to test parallel battery power output. If you have six 12-volt 75-amp batteries, the power output should be 12 volts at 450 amps, for a total of 5400 watts. It is OK if the reading is slightly higher in any area.

Solar Panel Connection

1. Test the solar panel with a multimeter before proceeding to make sure it is functioning properly. You may choose to cover the solar panel with cardboard to reduce the possibility of shorting out the wiring while connecting to the batteries.

2. Strip 5/16-inch insulation from both the red and black wires connected to the solar panel.

3. Crimp a terminal connector to the end of both wires

4. Connect the red wire to a positive (+) battery terminal on any battery.

5. Connect the black wire to a negative (-) battery terminal on any battery.

Tips & Warnings

• Do not overcrimp terminal connectors. Overcrimping may result in poor conductivity, broken strands of wire and loose connections.

• Installing a battery monitor or charge controller is advised to check battery charge rates and monitor battery health. The charge controller will be installed between the battery bank and the solar panel.

• Do not connect solar panel to the battery bank until all the batteries have been wired and tested.

• Never connect a battery to itself (positive (+) to negative (-) on the same battery). Doing so will short out the battery and possibly cause personal injury. You might also cause a fire or even create a battery explosion.

• Never cross connections from the solar panel if a parallel wiring method is used. This may damage all the components of your solar power system.

References

• Solatron Technologies: Learn About Wiring Solar Panels And Batteries
• Free Sun Power: Battery Wiring
• Solar Seller: 94 Battery Wiring Diagrams