Green energy systems such as solar and wind often use large banks of batteries to store power. You can get Renewable Energy (RE) batteries designed for these systems but some systems have successfully used forklift batteries. In either case you'll need to have a battery changing system to maintain the network at its peak.
The sun isn't always up. The wind isn't always blowing. Green power systems get around this by storing excess power in banks of batteries, creating a reserve during periods of low or no generation. Systems connected to the electrical grid don't necessarily need batteries since they can use the grid as a type of storage, selling excess energy to the power company and then buying it back when in need.
If you aren't familiar with banks of storage cells, you may not be aware of the "weakest link" factor. The storage network is only as strong as its weakest battery. Imagine running a fleet of forklifts where the entire fleet stopped working if a single battery lost power. That's how these banks of batteries work. It is essential you stay on top of weak batteries, swapping them out with a battery changing system before they cripple your system.
Are RE Batteries Worth It?
Manufacturers developed RE batteries for the renewable energy industry. These high-capacity cells are ideal for large power storage needs but can be expensive or hard to find. Organizations running renewable energy networks in remote areas might find it easier to lay their hands on forklift batteries.
The system needs deep-cycle batteries and forklift cells fit the bill. They are sometimes, though not always, cheaper than RE batteries and are certainly more plentiful. You may also find some battery lifters aren't sized to handle the big RE batteries, though Multishifter battery changing systems are designed to handle a wide range of battery sizes. So in answer to the question, yes RE batteries are worth it...except when they are not.
Used Forklift Batteries
The real advantage of forklift batteries comes when you are willing to incorporate used batteries in your network. Many forklift fleet managers get rid of their batteries when they still have a lot of life rather than risking the cells going bad at an inopportune moment. They sell these units at a fraction of the cost of new ones. To be fair these batteries have less shelf life than a new cell and that's why you will need a battery changing system to swap out cells as needed.
The real advantage of used batteries is the environment benefit. The best kind of recycling is reuse. If you can get a couple more years out of a used battery, then you are conserving the energy that would be used to manufacture a new one.
Used forklift batteries are an interesting and inexpensive alternative to new RE batteries as long as you have a reliable battery changing system to keep your network in top shape.