The solar battery bank is the most important component of a PV system. It stores electricity produced by your panels during the day and provides power to your home in the evenings. Not all batteries are created equal, so choosing one can be tricky.
The types of solar battery banks are compared based on capacity, depth of discharge (DoD), round trip efficiency, and battery life to find the best batteries for different PV system needs. The same advice can apply when installing any type of battery bank: bigger is better; however, it’s important you know what your home or business’ electrical demands will be so you buy an appropriate size. In this blog post, we will compare different types of solar batteries based on their capacity, depth of discharge (DoD), round trip efficiency, and battery life to find the best one for you!
- The size of a battery bank is determined by the storage capacity. A solar panel can produce about 20 watts per square meter, so if you have one-square-meter panels on your roof (about 100 watts) then that would be enough to power one light bulb for an hour or two. If you wanted longer-lasting lights, you might choose more efficient CFLs with a few hours worth of brightness each instead. Capacity has the inverse relationship with depth of discharge: as batteries get larger they also store less energy and tend to perform worse in cold weather.
- Depth of discharge (DoD) is the fraction of a battery’s charge that is used before charging it again. A depth of discharge of 50% means halfway through the storage capacity, while a 100% discharge would mean emptying out all the energy stored in an entire bank as if you had drained your car’s gas tank down to zero. Depth of discharge has a direct relationship with round trip efficiency: lower DoD batteries are more efficient because they recharge less often and can perform well at cold temperatures when discharged less during winter months.
- Round-trip efficiency measures how much power is lost between generating solar electricity and using it after being converted back into AC current. This number takes into account both losses due to conversion (such as from DC to AC) and losses related to inefficiencies in the system (such as when a battery converts AC to DC). Also, round trip efficiency measures how much electricity it takes from the grid compared to what it stores in its cells; this ratio should ideally be greater more frequent replacement than one that lasts longer would.
- Battery life: Batteries are also rated based on battery life which measures the cycles of use it can withstand before its capacity drops below 80% (the average is about 400-500). These ratings should be considered together when choosing a solar storage system. Batteries with high round trip efficiency but low life span might not work as well for someone who needs to store and release energy quickly, say for an emergency generator or off-grid cabin; those batteries would need to be replaced more often.
The type of solar batteries you should use depends on your household size, energy needs, and what types of loads are used. For domestic users who only have low-power lights in their home, for example, an off-grid bank with 100 watts (W) per day capacity might suffice. Likewise, if they live close to town and get the most power from the electricity grid then deep discharge or high efficiency is less important because any excess PV power can be traded back into the electric utility company’s network at very competitive prices so that it can make its way to those customers who need it over time without them having to buy expensive backup storage systems like large banks of batteries. Different types of batteries are discussed below so that you can choose which one is best for your needs:
- a) Lead Acid Batteries – This type of battery has the most capacity, but it also suffers from a low round trip efficiency because lead-acid chemistry is not very efficient at converting DC to AC (it’s more suited for charging and discharging). Lead-acid chemistry also results in lower life expectancy than other types of solar batteries such as Lithium-Ion or Nickel Iron Oxide. The result means less power available over time when using these kinds of batteries. They’re cheap though, costing around $1000-2000 per kilowatt-hour (kWh) compared with Lithium-ion which costs closer to $4000 kWh installed cost.
- b) Lithium-Ion Batteries – Lithium-ion batteries are more expensive than Lead Acid, but they have a high round trip efficiency and long life. They’re around $1000-2000 per kWh which is about the same as the lead-acid cost for capacity (but not the depth of discharge). Their low maintenance costs make them an attractive option because there’s less chance of corrosion damage from improper storage which can reduce battery lifespan. These kinds of solar batteries also perform better in cold climates compared to other types like Nickel Iron Oxide or Lead Acid due to their higher electrolyte concentration. The drawback with lithium-ion batteries is that you’ll need a lot more space on your roof if you want enough power for daytime usage so it should be considered when designing a solar system.
In conclusion, there’s no definitive answer to which type of battery bank will power your home best because different types have their own advantages and disadvantages–but now you’re armed with enough information to make a decision. If you’re interested in solar power, check out more battery options here.