There are two main types of solar batteries: the deep cycle and the regular (or shallow) cycle. A regular battery can be used for appliances, while a deep-cycle is best suited to power tools and other devices that regularly demand high amounts of energy or require long hours of use.
Both types feature lead-acid cells that deliver what is called an “open circuit,” meaning there is no current flow when they are not connected to a circuit. When connected, electricity flows from the positive terminal to the negative one; this process recharges the batteries’ cells. After recharging, these batteries appear as though they have been drained — because they actually have been: The charging process isn’t 100% efficient and some energy is lost during reconditioning.
One main difference between deep-cycle and regular batteries is that the former is rated at 100 discharge/charge cycles, while the latter tend to last 1,000 or more. Regular batteries also have a higher energy capacity than solar cells do — these power plants deliver about 50 amp-hours per day as opposed to 1,500 for a standard battery.
The typical operating voltage of a lead-acid cell is 2 volts each, so six would be required to create 12 V for your system’s battery bank. Sixteen would be needed to produce 24 V and 24 cells would provide enough juice for 48 V.
Solar panels should not exceed 80% efficiency because this can damage the cells over time by driving too much current through them. When a bank is fully charged, any excess energy should be diverted to a moderate load that does not overload the system.
What determines how many batteries one should have in their bank for their solar panel system?
The voltage needed-the amps per day needed to run the appliances in your home. For example, if you have an electric stove, air conditioner, water well pump and lights in your house then you would need to have a 48-volt battery bank.
The amount of sunlight. If you live in a sunny area then you will need less storage. If your home uses a lot of energy on a cloudy day, the battery bank may become depleted.
The inverter’s efficiency. if your inverter is 80% efficient you will need to have more storage in the bank so you can get through cloudy days.
The time to recharge the batteries from solar power. If you have a smaller battery bank, it will take longer to recharge. If you have a large battery bank it will take much less time to charge.
The number of days you wish to be off-grid for. If you are only going to be off-grid for one day, then you do not need a large battery bank.
We recommend using our Solar Energy Calculator for a better estimate of what you’ll need.
How can one reduce the loss of electricity when recharging batteries?
You can get special charge controllers that help reduce this amount by taking less from your panels before sending it to your batteries. This helps keep your battery bank healthy for longer.
You can also get a charge controller that is designed to increase the discharge speed of your panels. This will give you more watts per day over the discharge speed and decrease the amount of time it takes to recharge your battery bank.
What is the best battery for a solar panel system?
If you are looking to power your home or cabin and you want to be completely off-grid, we recommend a 12-volt system with at least 8 batteries.
Some of the top brands for solar panel batteries are:
- Optima BlueTop Battery
- Trojan T105-RE Battery
- Enersys Liberty SW145R Sealed Lead Acid Battery
- Deka ETX14L-BS SLA Battery
- East Penn Deka MZE151-G Deep Cycle Battery
- Surrette S530
These are some of the top brands as they currently stand as of January 2022. They may be updated as time goes by and technology improves but these are top-rated batteries for this category at this current moment in time. Some other types, such as wet cell batteries, have been outlawed from solar panel systems because of their tendency to explode through loss of fluid. Gel cell batteries do not work well with off-grid systems and start to fail above 0 degrees Celsius (32 Fahrenheit).