3 Cheapest Ways To Store Solar Energy

Solar energy is rapidly becoming one of the most popular renewable energy sources. It is an abundant, clean, and cost-effective energy source that can power homes, heat water, provide light, and even power electric vehicles. However, it’s difficult to harness the potential of solar energy if you can’t store it.

Lead-acid batteries, lithium-ion batteries, and solar generators are the cheapest ways to store solar energy. Lead-acid batteries have a lower upfront cost, but lithium-ion batteries are considered the best choice. Most solar generators use lithium-ion batteries.

Below, I’ll go over these three cheap portable solar solutions. I’ll discuss solar storage and why you may need to add it to your solar system.

1. Lead-Acid Batteries

Lead-acid batteries are one of the cheapest ways to store your solar energy. This type of rechargeable battery uses a chemical reaction to convert solar energy into stored energy.

Though this is one of the cheapest battery types, it has some significant disadvantages.

There are three types of lead-acid batteries:

Flooded. The average life of flooded lead-acid batteries is about 12 years. This is also the only type of lead-acid battery that could require some maintenance, while the others are maintenance-free. It has the lowest upfront price as well.
AGM. AGM lead-acid batteries also have an average life of about 12 years. It requires no maintenance but is the second cheapest of the four lead-acid battery types.
Gel. Gel batteries have a longer lifespan than lead-acid batteries at 20 years, but this also increases the cost, making them the most expensive. Gel batteries don’t require maintenance.

Average Cost of Lead-Acid Battery Storage

Although you can buy cheap lead-acid batteries for $200–$400, these will only do for campers with small solar systems. If you plan to power your house, going for other types of batteries becomes more cost-efficient, even if they have a higher upfront cost.

Expect to pay around $500–$1000 per kilowatt hour when purchasing lead batteries.

Benefits of Lead-Acid Battery Storage

Here are the main benefits of lead-acid batteries:

Cost. They’re one of the cheapest ways to store your solar energy.
Accessibility. There are many different types of lead-acid batteries to choose from and many manufacturers who make them. This allows them to stay low-cost.
Reliability. Lead-acid batteries are a tested and true method for solar storage, so you can have peace of mind knowing you will have energy when needed.

Drawbacks of Lead-Acid Battery Storage

These are some of the most significant drawbacks of lead-acid battery storage:

Sulfation. Sulfation happens when the battery is discharged to a very low level. It interrupts the flow of the natural chemical reaction. When this happens, the battery gets internally coated with lead sulfate, rapidly reducing the battery’s lifespan. To keep this from happening, it should never be discharged to less than half of the storage capacity.
Short lifespan. Especially when cared for improperly, lead-acid batteries can die quickly, increasing costs if they need to be replaced often.
High maintenance. Most lead batteries require much more maintenance than their lithium-ion counterparts. You might have to have them checked as often as every three months. While gel and AGM lead-acid batteries require minimal maintenance, they can’t handle as much current, making them only suitable for small solar systems.

2. Lithium-Ion Batteries

Though many kinds of batteries are available to store solar energy, storing solar energy with a lithium-ion battery is the most cost-effective and efficient method in the long run.

The upfront costs can be high, but these batteries are much more resilient, while some of the cheaper options may need to be replaced sooner. If you are very invested in solar energy, this is the route you’ll want to take.

We’ll likely see new battery technologies emerge in the future that drastically reduce the overall cost of solar energy. However, it’s widely accepted that lithium-ion batteries are the best way to store solar energy right now, and it will likely be so in the near future. This is for commercial use—large-scale solar systems have other options at their disposal.

Average Cost of Lithium-Ion Battery Storage

Lithium-Ion batteries can be costly up front, with some installations being around $30,000. A 15 kWh lithium-ion battery can cost anywhere from $5,000 to $15,000.

Some may turn away from lithium-ion due to the upfront cost. However, this type of battery storage can justify the cost and save money in the long run. It may not seem “cheap,” but it will cost you less than most lead-acid batteries after a few years.

Most lead-acid batteries last between 3 and 10 years. Depending on the use you give it, your average lead-acid battery will fall on the lower end of that spectrum. Meanwhile, lithium-ion batteries last for 10–15 years.

If you consider the cost of replacing lead-acid batteries for over a decade, lithium batteries start to look like a budget-friendly choice.

Benefits of Lithium-Ion Battery Storage

There are many benefits to storing your solar energy with a lithium-ion battery:

Long lifespan. Lithium-Ion batteries have a very long lifespan. Despite the costly installation, you can rest easy knowing they will last a very long time.
High depth of discharge. Lithium-Ion batteries are deep cycle batteries, which means they have a 95% depth of discharge rate. This allows you to use much more of the energy stored in the battery without charging as often. To give you perspective, lead-acid batteries usually have a depth of discharge of 30%-50%.
More power storage. Lithium-ion batteries can store much more power than other solar storage methods and take up less space.
High efficiency. The more efficient the battery, the faster it can be charged. High efficiency also means more of the stored energy can actually be used. Lithium batteries have an efficiency of 95%, while lead batteries only reach 80% to 85%.

Lithium-ion batteries tend to be pretty easy to come by, too.

Downsides of Lithium-Ion Battery Storage

The above may make lithium-ion batteries seem foolproof, but they can have a few issues.

High cost. The upfront cost can be too high for those looking for a cheap way to save solar energy.
Potential to overheat. Lithium-ion batteries can overheat and cause a fire. If properly installed, this is rarely an issue, but it’s still something to be aware of.

3. Solar Generator

We’ve explored two options for building battery banks. This is the most common strategy for those who want a solar system big enough to power a house. Even if you only want to power a van, you’ll need at least a couple of lead-acid batteries if you plan to use many appliances.

But what if you have small energy needs? Maybe you want to use solar power to charge your laptop or a few electronics on a camping trip.

In that case, you’ll be fine with a solar generator.

Solar generators can be a fantastic, cost-effective choice for storing solar energy. They typically come with attached solar panels, making them a good option for those exploring solar energy.

Solar generators store energy using lithium-ion batteries. The smaller the solar system, the more efficient it needs to be, and for something as portable as a portable solar generator, it makes no sense to go with lead batteries.

You can also use large solar generators to power a home, but if that’s your main need, you should probably look for a fully-fledged solar system.

Average Cost of Solar Generators

The price range for solar generators can vary greatly, depending on what you’re trying to power. For example, if you only need to power a laptop or a light, this can be a purchase price of around $100.

For items that need more power, such as a microwave or refrigerator, the generators will need much higher capacities, costing you around $2000–$4000.

Suppose you want a solar generator to power something as significant as your home. In that case, the cost will be anywhere from $7,000 to $50,000.

Benefits of Solar Generators

Solar generators can be an excellent choice for storing your solar energy on a small scale. Here are some of their benefits:

Portability. Solar generators come in many sizes, many of which are portable. You can bring them camping, to the park, and other outdoor activities. They’re also great in an emergency while you’re out on an adventure.
Quiet. Most people think of generators as loud, but solar generators are completely quiet. You won’t notice them as they do their job.
Low maintenance. Compared to traditional energy generators, there is little to no maintenance needed for solar generators. You can use them whenever you need them!

Drawbacks of Solar Generators

As convenient as they are, portable solar generators can’t match the sheer capacity of a proper solar system.

Lower energy storage. In an emergency, such as a power outage, a generator might not have enough stored power to power everything you need—just the bare necessities. However, it’ll still power more than the above batteries will.
Slow to recharge. Solar generators can be slow to charge even if the sun is bright. This can lead to gaps in power.

If you’re on a lower-end budget, though, a solar generator is a great first investment for starting your solar energy journey.

How Long Can You Store Solar Energy?

Most batteries allow you to store solar energy for 1–5 days. After that, the battery will start to lose power. That’s enough for most camping trips, especially if you can charge the generator on the go.

For longer outdoor stays, ensure you’re taking enough solar panels to keep up with your energy demands.

This period is highly dependent on the size of the battery and the brand. Some higher-end lithium-ion batteries, such as the ones Tesla makes, can hold charge for seven days.

This estimate applies to batteries in good shape. Lithium-ion batteries lose their capacity to hold a charge over time, so a battery that’s near the end of its lifespan will hold power for a much shorter time.

What Is Solar Storage?

If you’re looking at solar storage options, I’m going to assume you know already that solar energy has incredible benefits for practically everyone. Those who care about the environment can rejoice in its ability to reduce greenhouse gasses, and those looking to save a bit of money are glad they switched from traditional energy sources.

Solar storage is the process of capturing the energy from your solar device and holding onto it so it can be used when it is most needed. When you store your solar energy, you can then use it for other things in your household and truly harness the benefits of solar energy: batteries for toys or flashlights, charging your phone, or powering appliances during a blackout.

If you don’t store solar energy, your system will deliver power as it is coming in, which means it won’t be helpful when the sun goes down. Besides, any extra solar power harvested will go to waste.

If you’re out camping or you’re planning to rely solely on solar energy, then solar storage becomes a necessity. You’ll need to invest in a decent array of batteries. If you want to get the most out of your complimentary solar system, you can get away with fewer batteries.

Can You Store Solar Energy Without Batteries?

Believe it or not, you can! However, storing solar energy without batteries is usually only reserved for large-scale operations.

The most common non-battery-based method for storing solar energy is pumped hydro. The principle is extremely simple: you use the excess power created by your solar panels to pump water up a hill and into a tank. Then, whenever you need energy, you can use the force of gravity to spin a water turbine and create electricity.

Needless to say, this method isn’t practical in most scenarios, especially if you want a portable solution. Even if you want to power a house, an array of lithium-ion batteries may prove to be more practical.