How to connect solar panel with battery

Connecting solar panels to a battery is a convenient and cost-effective way to keep your power supply fully charged. This is especially useful for outdoor equipment such as golf carts, power boats, and tractors that may not see use for days or weeks. Connections are easy to make. Getting the job done right requires some simple math to calculate the number of solar panels needed to charge a battery at a specific amperage. In this article you will learn how to do it.

Determines the amp hour rating of the battery to be charged. A wet cell battery loses 1 percent of its amperage per day when not in use. This means that the solar panel with each passing day will have to deliver 1 percent of the battery’s total amperage to maintain a full charge. For example, a solar panel must be able to produce 0.5 amps per hour per day to hold a 50 amp battery charge. But solar panels are rated in watts, so some simple math is necessary.

Convert the solar panel’s rating from watts to amps by dividing the panel’s watt rating by 15. A 50-watt solar panel has a rating of approximately 3 1/3 amps. Factoring in clouds, bad weather, and obstructions during sunrise and sunset, a solar panel should deliver about four hours of average output per day.

So a 50 watt panel would produce 4 x 3 1/3 amp hours per day, or 13 1/3 amp hours. More than enough to maintain a 50 amp battery at full charge.

1- Connect the positive cable from the solar panel to a battery cable with a fuse between the battery and the solar panel. This will help prevent a fire or battery explosion in the event of a short in the wiring.

2- Connect the negative cable of the solar panel to the negative terminal of the battery.

4- To interconnect solar panels to charge a battery, connect the panels in a parallel circuit. This allows you to use multiple lower cost, lower wattage panels to achieve the same result as one more powerful panel.

5- Connect the solar panels in parallel by connecting the positive cable of the first panel to the positive terminal of the second, and so on.

6- Connect the negative cables in the same way and the remaining cables in the last panel connect them to the battery.

Calculate the total amperage of the solar panels connected in parallel by adding the amp output of each panel. Panels connected in parallel maintain the same voltage across the circuit, while the current builds up. For example, 10 five-amp solar panels would yield 50 amps of power at constant voltage.