What are battery bank storage systems?
Battery bank storage systems (or just batteries, if you prefer) are battery systems that can be used to store all the power generated by your solar array or wind turbine. A battery bank will store energy when it’s being generated (i.e. when the sun's shining or the wind's blowing), and feed it from the batteries when it’s needed. A solar array, for example, will generate power all day, but obviously stops generating power once the sun goes down. Saving it up in a battery bank allows you to use power generated by your solar panels when it normally wouldn’t be available.
The batteries in a renewable energy array need to be 'deep cycle' batteries, or they won't last long. Deep cycle batteries are specifically designed to release energy and recharge on a regular basis, and can withstand many cycles of use before wearing out. These batteries can suffer if they are left to get too low though, so having a charge controller which stops the flow out when the battery reaches around 50% is a good idea.
How do battery banks work?
Battery banks are typically connected to a charge controller which acts like a tap, diverting power if the batteries reach capacity. The charge controller stands between the solar panels or wind turbines and the battery. Energy generated by the turbine or solar array will come in as DC, and this is how it's stored in the battery. The output of the battery is connected to an inverter, where the current is converted from DC to AC so that it can be fed into the mains power in your home - or possibly also to the grid.
How are battery banks installed?
Battery banks will typically come as part of the installation kit if you've opted to have one installed, and will be set up along with the rest of the system. Battery banks are normally installed in a safe, dry place off the ground - either inside your home, or in a garage. Since they will require electrical wiring, especially in cases where you're connecting to the grid, installing them is a job best handled by a licensed electrician.
What variations are there in battery banks?
The key variation point for batteries is obviously capacity. When creating a battery bank, get an estimate of how much power your system is expected to generate per day and how much of it you’ll use around your home. This will give you an indication of how much you’ll need to store in reserve. Remember, a high efficiency system is no good to you if you're generating energy that’s going to waste because you haven’t got sufficient room in your battery bank to store it for when you need it most.
Physical size can also be a factor, as the larger capacity batteries can take up a lot of space.
What to look for
Deep cycle batteries are definitely required - simple car batteries just won’t do. Make sure your batteries are all purpose-built deep cycle batteries, and you will see at least 5-10 years of constant use from them.