Solar Batteries

Renewable and Sustainable Energy with Solar Energy

Skill Level
20 Min

Chapter 3

Solar Batteries

Storage batteries are one of the most essential parts of a solar energy system. There are different types which serve various functions to make the solar energy system better. Because of this, their price is also considerable.

That is why, before you buy a solar battery, you should be well-versed with the different types, their advantages and disadvantages.
This chapter is going to do precisely that. We’ve summarized all the essential information relating to solar batteries so that you can be fully informed before you make any purchasing decision.

Do I Need Batteries For My Solar Energy System To Work?

solar energy storage battery

A lot of people consider buying batteries alongside their solar energy systems. Batteries are sold separately from solar energy systems. The cost of the backup batteries has fallen over the past few years. They are becoming one of the primary components of solar power systems. 

The price of solar batteries falls within a range of $7,000 – $15,000. Although most people find the option of running home appliances independently appealing, the truth is that solar batteries are not strong enough to run your entire house. They can only power a limited number of devices, and that too for only a day.

Your solar batteries will only function for approximately twenty-four hours, after which they should be recharged. So, you should keep in mind that you need a sufficient amount of sunlight to recharge your solar batteries fully.

Integration of Solar Batteries In Existing Systems

Integrating solar batteries into an already existing solar energy system is also tricky. The ease of installation depends on solar energy system’s design compatibility with batteries without a lot of modifications.
Such systems are called storage-ready networks because they already feature an inverter, which makes it more straightforward to add a solar battery. There are also few equipment needed.
Such systems are called storage-ready networks because they already feature an inverter, which makes it more straightforward to add a solar battery. There are also few equipment needed.
However, if your solar panel system is incompatible with batteries, there might be additional difficulties.
In this case, you can choose from one of two options.

Purchase and Install An Extra Inverter

The first option is buying and installing an extra inverter for your device. The benefit, in this case, is that you keep your first inverter and save some money. You can also install a comparatively larger battery for your solar energy system.
The disadvantage is that your system’s efficiency decreases in the long run.

Replace Your Current Inverter

The second option is to replace your current inverter with one that is compatible with your solar battery. Keep in mind that your new inverter’s life will be somewhere around 10 years. If you have a solar panel that is at least 5-6 years old, you may want to consider changing your system altogether.
The advantage you gain from this is greater efficiency, i.e., your solar panel will save more energy. However, the costs will also be higher, since replacing your inverter with a new one is costly. Furthermore, the installation of the new inverter may require specific changes and rewiring in your system, so be prepared for those costs as well.

Selling Solar Batteries

Another reason why people may be drawn towards solar batteries is that they give you the option to sell your extra electricity reserves to other companies. For example, popular companies such as Adara Power and Sonnen Inc. claim that their batteries make electricity available to you for a mere $0.4 per kilowatt-hour.
But the truth is slightly different. Local electric companies sell the same amount of electricity for a mere 0.1$ – 0.25$. Therefore, it makes much more sense to obtain it from them.
There are two groups of people who can achieve an overall benefit from buying solar batteries. The first are those who experience frequent power failures. In such a scenario, solar batteries prove helpful as they are used when electricity is not available from the grid.
The second group of people are those who are financially well-off, and the costs of buying a solar battery will not affect them that much.
Such people can also reap the additional benefits which they will gain from purchasing a solar panel. These benefits include:
  • saving money by using less energy from grid-tied systems
  • contributing to environmental protection by not using coal-power generators
  • achieving independence in use and distribution of electricity.

The prices of batteries are likely going to drop further in coming years. This may lead to electrical companies offering a more significant amount for their electricity reserves to smooth out grid-tie fluctuations.

Another smart use of solar batteries may be to charge them when electricity costs are low. Then, make the electricity available for use or purchase when prices are high.

Which Type of Battery Is Best For Active Solar Use And Why?

Acid battery
f you want to purchase a solar battery, you should know the different types available and their merits. There are 3 main types of solar batteries:
  • Lithium Iron
  • Nickel Iron
  • Lead Acid.

The Pricing

Let’s talk about solar energy storage batteries prices first. Lead-acid will cost you the least in comparison to the others, but that is only with regards to its upfront price. In the long run, lead-acid batteries will cause you more.

For long-term planning, Nickel-iron batteries are the most suitable, as they cost the least. However, you will have to maintain these types of batteries with regular inspection and monitoring.

Lithium-iron is also a viable option. Although it is slightly higher in price than Nickel-iron, its long term savings are as good. More importantly, there is no maintenance required at all.

Performance and Life Cycle

If we study a comparison chart of the three types of batteries, we find that Lithium Iron tends to perform the worst. It has a low life cycle coupled with a low depth charge of around 50%. Even worse, the battery bank requires regular replacement, which will drain even more money. Nickel iron batteries have a much longer lifespan of around 30 years. The depth discharge, however, is the same.

If you’re searching for a short term solar battery, then lead-acid will be the preferable option. They perform optimally for several years, even 5 to 7 years if you use them carefully. However, for a more reasonable period, lithium-ion batteries are the best option as they do not require any replacement or maintenance and can easily last for 10 to 15 years.
Nickel iron batteries last for 20 to 30 years. If you are searching for a solar battery that will last that long, then they are worth consideration. They require regular maintenance as well. Therefore, be prepared for that if you decide to buy them.

Functionality In Diverse Environments

The next factor to consider is functionality in different temperatures and environments. Nickel Iron batteries are the leaders in this category. They have vast charge and discharge rates from -20 to 144 degrees Fahrenheit. Sub-zero temperatures do not damage lead-acid batteries.
Lithium-ion batteries only have a full discharge rate at the range of -5 to 140 degrees Fahrenheit. Charging these batteries in freezing temperatures can cause permanent damage.
Lead-acid batteries have a modest discharge rate of temperatures ranging from -4 to 144 degrees Fahrenheit. Charging them, however, has to be done carefully as the battery cells can freeze at a temperature of 32 degrees Fahrenheit when being discharged.
Nickel iron batteries are off-grid batteries. They can operate independently and tolerate high levels of changes in electrical surges.
Lithium Iron and Lead Acid batteries are both connected to the local power grid. Whereas lithium-ion batteries are lightweight and can show the current electrical levels in a simple format displayed online. Lead-acid batteries are difficult to maintain and regular discharges of large currents can damage them.

Discharging Rates

Next, we turn towards discharge rates when comparing and contrasting the 3 types of batteries.
Nickel iron batteries work best under medium charge and discharge rates while Lithium-ion batteries can tolerate high discharge rates. Lead-acid batteries can only work under slow charging and discharging rates.

Cost of The Battery Types

The last thing to consider is the overall cost of the three batteries.
Nickel iron batteries typically carry a $1 per watt cost for a lifespan of 30 years. Most of the substantial costs are incurred when paying initial cost. Nickel iron batteries have a $1.5 watt-per-hour cost for a lifespan of approximately 15 years. There are no maintenance costs to consider.
Nickel iron batteries have a 2-5 watt-per-hour cost for a life of 30 years in which they require around 4 replacements over the period. Not surprisingly, they have the highest costs of ownership.
It is clear that unless your goal is strictly to obtain a battery for a short period, lithium iron and nickel-iron batteries are much better candidates. The two have a low cost relative to lead-acid and also offer better performance.

What Are Grid-Tied Systems And Why Are They Better?

On-grid systems are systems in which your solar batteries are connected to the local power grid and are not producing power independently. This benefits you in several ways.


The first benefit is that any excess power produced can be transferred to the local energy grid for credits. You can redeem the units in your account during cloudy days and at night. You can store credits in your account and then use them when your solar battery’s output is low. These credits can also help in reducing your electricity bill. Households connected to grid-tied systems have the option to store and sell their electricity to other parties for a profit.

No Additional Equipment Required

The second advantage of grid-tied systems is that they require no additional equipment for your solar panels. Individuals who use grid-tied systems also don’t have to worry about the problem of extra costs of buying solar batteries, which independently produce power. The issue of money being spent on maintenance is also minimized.

Reliable Source

Lastly, grid-tied systems are an excellent way to be connected to a secure, reliable source of energy. Off-grid battery owners face problems when it is mainly cloudy on a particular day, and their solar panels do not produce enough electricity.
In contrast, grid-tied systems work differently. When you harness extra electricity, you can sell it for a profit. When your solar panels are not working at the optimal level, you can get electricity from the grid. Therefore, the power supply to your house always remains constant and reliable.

Key Takeaway

Well, that’s all the essential information you need to know regarding solar batteries. Always make sure to carefully weigh each alternative and all the pros and cons before making a decision. Also, keep in mind that solar battery technology is undergoing rapid advancement in current times. The future will surely bring many more types, which may offer even superior performance.
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