Solar power is a huge industry that keeps growing and becoming more accessible to families and suburban neighborhoods. When shopping or exploring the idea of switching to solar, there is a wide range of questions you should be asking.

But, one of the most important ones is, “How long will my solar battery last?” 

Solar batteries can last anywhere from 5 to 15 years depending on the battery, the weather, and how often they get charged and drained.

You may be wondering now, “How do these factors affect the life of my solar battery, and what can be done to elongate the lifespan of my power source?” Read on to find out!

To understand why solar batteries have a lifespan, we first have to look at what solar batteries do, and how their effectiveness decreases over the years.

So, to give you a better understanding of how the batteries work, let’s look into the technology and science at play. It may sound crazy complicated, but it can be simplified into totally understandable concepts.

How Solar Power Works

In the most basic way of explaining the general functionality of most solar panels, there are two pieces of silicon inside each of the panels. The top one has phosphorus in it, giving it a positive charge, while the bottom has boron, making it negatively charged. 

There is a small junction between these that is full of conductive wiring. When light hits the panels, tiny energized particles called “photons” that are in the sun’s beams hit the positively charged molecules in the top layer, causing electrons to get knocked loose, and then get pulled by the negatively charged molecules at the bottom.

The positively charged side has a surplus of electrons, while the negative side has a deficiency, which is what pulls the electrons to the negative side after being pushed by the photons via the law of attraction which says that opposites attract.

The electrons never actually make it into the negatively charged area since they get picked up by the conductive wires in the junction between the layers, and transported to the battery where they are stored to be used later.

Battery Life

The battery life of your solar battery is similar to the battery life of a cell phone. Each time the battery runs through a cycle, (charged and drained) it loses some of its ability to hold the charge naturally. There is not much that can be done to prevent this loss.

So what does it mean, it is just like a cell phone battery? Well, each time your cell phone is charged, and then the battery used up and drained, the cell phone battery loses part of its ability to hold a charge.

Eventually, as the cell phone gets older and used, you will probably notice that the battery is not lasting as long as it did when you first bought it. This is due to the amount of charge it is able to hold getting lower over time and with each cycle, which is just like what happens in a solar battery.

The sun charges the panel, the energy is transferred, captured, inverted, and then stored in the battery. When that energy is drained from the battery, a small amount of the ability to hold charge goes with it.

Solar batteries might come with warranties for a certain number of cycles or years that ensure the battery will not go below a certain percent of its original battery capacity.

An example of that type of warranty could be like this: the battery will not lose more than 35% of its original capacity over 7,000 cycles or 15 years, whichever comes first. This means that when the warranty is over, the solar battery will not have lost more than 35% of its function in that time frame.

All warranties are different and depend on the brand of solar battery, the type of battery, and other factors but almost all manufacturers of solar batteries will provide a warranty on the battery.

Since all batteries are different, it is difficult to pinpoint the exact number of years, but the different types of batteries have an average number of years that they can run for if given proper care.

Lead Acid

Lead-acid batteries are most commonly used as car batteries where the electrodes are in grids of metallic lead oxides that change their chemical composition while being charged and while using the power. It uses a diluted form of sulfuric acid as the electrolyte to carry the current.

The progression in the AGM batteries has made lead-acid batteries one of the best batteries for solar power.

The industrial style of a lead-acid battery can usually last up to 20 years with proper maintenance and care, while a standard battery should last around 3-5 years. Intermediate batteries should last around 7-12 years with proper care.

Lead-acid batteries are known for being fairly good batteries with decent lifespans, depending on the brand of battery.

Lithium-Ion Batteries

Lithium-ion batteries are highly praised as solar batteries since they are lightweight, compact, and have a longer lifespan than standard and intermediate lead-acid batteries. 

The cost of lithium-ion batteries has gone down as demand has gone up, making them one of the most cost-effective options.

Lithium-ion batteries can last up to 15 years and are well known for their solar storage capabilities. These batteries are largely considered the best solar batteries because of their lifespan, reliability, and high storage capacity.

Saltwater Batteries

Saltwater batteries are a more environmentally-friendly version of solar batteries and thus make the solar energy and clean battery image look very nice but they are not as well praised as lithium and lead-acid batteries.

Instead of using heavy metals as the electrolytes like lead-acid batteries and lithium-ion batteries, the electrolytes in these batteries are a simple saltwater solution. 

Saltwater batteries are way easier to recycle than lead-acid and lithium-ion batteries, but this comes with a price. They tend to take longer to store and discharge energy, typically at a lower strength.

Saltwater batteries are still not very well researched since they are such a new technology, and since they are largely untested, they come with a bit of a risk. They typically have a lifespan of around 8 years.

The way that each battery functions is different, especially when factoring in the different types of chemicals used in the batteries. Some are incredibly abrasive and will eventually damage the battery like lead-acid, while saltwater batteries have hardly any internal erosion. 

Others do not have that issue. It all depends on the battery in question. The way that the battery is cared for is another part of what makes a battery last. A solar battery could have a 15-year lifespan but die after 10 years because of improper care or neglect.

Overall, each battery will be different. The type of batteries listed above are three of the most progressive and well-praised styles of solar batteries and their lifespans are relatively long.

The lifespans they have are average lifespans and these time frames will differ based on the brand and model of battery. Each type will have further pros and cons based on the manufacturer of the specific batter which affects how the battery will interact with the rest of the solar power system.

If you are looking to purchase a solar battery, make sure that you thoroughly understand how your system works, and how the battery will work in it. Electricity and chemical batteries can be a tricky subject, so it is very important to be educated on the topic before purchasing or installing batteries yourself.