RENOGY® Solar Panel Starter Kit 400W Mono

Hi Matt,

In general, you want to look at 12V deep cycle marine batteries. Stay away from automotive batteries...they are designed to start engines, not for powering equipment for long periods of time. You'll connect these batteries in parallel so that your voltage remains at 12V while your storage capacity (IE current) combines together.

As far as the number (and type of batteries as far as capacity is concerned)...that really depends on what you're powering with the system. The greater your power requirements (and the longer you need to run them without recharging), the more batteries/greater reserve capacity you need. I'd look at having at least two deep cycle marine batteries with a reserve capacity of at 80AH to start.  Three 80 AH would probably be best...or less batteries with greater reserve capacity.

Look at it this way: Your solar panels are a "water pipe" coming from a creek with a variable flow rate of water. Sometimes the creek runs fast, giving you more water. Sometimes it dries up, giving you nothing. The pipe goes into a tank...that's your batteries. The tank has a spigot...that's what you're powering with the system.

Open the spigot wide open and you'll drain all the water from a small tank...unless the creek runs fast enough to keep it filled. The bigger the tank, the more water you can use before emptying it...but the longer it takes to refill it too.

A properly balanced system takes all of that into consideration. Remember, just because you have a Renogy Solar Panel Starter Kit rated at 400 Watts doesn't guarantee that you get that 400 Watts all the time. You also have to consider what you're planning to power, how long you plan to power it without any sun, and how long it will take to recharge the batteries afterwards. More batteries=more capacity=longer time to recharge, but more expense. Less batteries=less capacity=shorter time to recharge but less expense.