Which solar battery is best for energy storage?

Which solar battery is best for energy storage?

Even a decade ago, an entire country sustaining their electricity needs with renewable energy would have seemed impossible. Fortunately, countries like Iceland and Paraguay are already showing that becoming entirely reliant on renewable power is not only possible, but around the corner.

Unfortunately, South Africa still ranks in the top fifteen carbon emitters globally, by state and per capita. Our country produces 93% of its electricity through coal, which explains our disappointing numbers. Even more disappointing is the slow progress towards environmentally-friendly energy solutions, ones that experts across the country have suggested we are perfectly suited for, both climatologically and environmentally.

The rationale used by most governments that are slow to progress on these issues is that renewable energy solutions are only intermittent power sources and cannot reliably run an entire country. There is some truth to this statement, however, the real concern for renewables is not energy generation, but energy storage.

Battery energy storage is the key to turning nationwide renewable power solutions into a reality. In South Africa, and around the world, countries are awaiting better, more reliable and more sustainable storage for solar power. For the times when the Sun is not shining or the wind is not blowing, battery energy storage could hold and distribute power despite an uncooperative environment.

Finding the right battery storage technology is at the forefront of the solar industry’s development. By finding the right combination of systems and materials, we could make 100% renewable energy as reliable as any other source of electricity. In this article, we will discuss the incredible progress made by innovators in this field and why lithium ion is probably the best choice of solar battery storage, overall.  

What is a lithium-ion solar battery?

Battery technology has come a long way from Planté’s lead-acid batteries and AAs. Today, batteries are being used to power laptops, cell phones and, even, electric vehicles. Lithium-ion batteries are commonly used in rechargeable electronics and vehicles; known for their reliability and storage capabilities.   BMW, Toyota, Nissan and many other manufacturers of electric vehicles have led the developments and innovations behind lithium-ion energy storage.

South Africa’s own, Elon Musk and Tesla, are another powerful driver of lithium-ion technologies. They designed their “Powerwall 1” which was a large battery storage solution that uses several connected battery panels to store solar-generated power. This was built thanks to advancements in lithium-ion battery technology and inspired by the battery systems powering most of our electric and hybrid vehicles of today.

In the early 2000s, most solar storage systems were being built using lead-acid battery technology. Today, lithium-ion batteries are overtaking the market for solar battery storage. These advancements are slowly, but surely, lowering the entry price and increasing the accessibility of battery storage technology for residential or commercial properties. The question remains: has lithium ion become the best battery type for solar storage?

What are the benefits of lithium ion for solar battery power storage?

As lithium-ion battery storage continues to rise in popularity within the solar industry, it is important to understand what they offer and how they work. Lithium-ion will continue to replace lead-acid battery storage as the primary tool for solar power generation and storage. If we are unaware of the benefits of lithium ion compared to other solar battery storage types, like lead acid, how will we know if the future of electricity is truly sustainable?

The pros of lithium-ion solar batteries

  • A greater depth of discharge (DoD) 
    The DoD of a solar battery is the amount of stored energy that can be used (or discharged) during its use. The higher the DoD, the more reliably a battery unit can be used while maintaining its operational health. Lithium-ion solar batteries have a higher capacity and deeper cycles with a 95% DoD, as opposed to lead-acid alternatives at around 50%.
  • A longer lifespan
    The higher depth of DoD associated with lithium-ion solar storage means that these systems can go longer without recharging or dropping below their DoD threshold. That means a longer lifespan and, as such, come with guarantees that cover about 10 years or 10,000 cycles. Lead-acid batteries with have a lower DoD and are less reliable – only offering guarantees for 5-year lifespans.
  • Higher energy density than alternatives
    The energy density of a battery storage solution is measured by the amount of electricity that can be stored relative to its physical size. As you can guess by this being a pro, lithium-ion batteries hold more energy in less space than other alternatives, making them ideal for home use.
  • More efficient
    Lithium-ion batteries have a much higher total efficiency than other solar batteries. Total efficiency is measured by how much excess energy is used to store and distribute usable energy. Lithium ion has an efficiency of over 90%.
  • Fewer maintenance requirements
    A longer lifespan and higher efficiency also require lithium-ion battery users to conduct less maintenance. Their systems work better for longer which is invaluable to homeowners, unlike their lead acid alternatives.

The cons of lithium-ion solar batteries

  • They can be expensive
    As a newer technology, lithium-ion batteries can be an expensive option. However, as lithium-ion solutions are evolving, they are becoming more affordable than most lead acid and other alternatives.  In addition, government-supported tax rebates and credits, longer lifespans and higher DoD means that lithium ion is widely considered the most valuable renewable power storage option.
  • Off-peak or conditional reliability
    This is not, necessarily, a con of lithium-ion solar batteries, rather cloudy and windless days. These, for example, can be devastating to renewable power users if their battery storage is not up to snuff. Fortunately, the improved efficiency and reliability of lithium ion reduces the impact of intermittent weather on power stores.
  • Possibility of thermal runaway
    Lithium-ion batteries are known to run a higher risk of thermal runaway events. This is a minute risk for well-installed systems, however, superheating or catching on fire is a possibility.

Are lithium-ion solar batteries the best for energy storage? 

Lithium-ion have proven to be a more reliable and efficient means of solar power storage for residential and commercial users. The high DoD and efficiency levels help these systems perform better and last longer. Lead-acid battery storage can be preferable as a back-up power source for blackouts or in an infrequently-visited, off-grid holiday home. The reality is that environmentally-friendly and sustainable electricity generation is the future of energy, lithium ion may be preferable to lead acid, but any renewable power alternatives are a step in the right direction.

Solar 4 Life are at the cutting edge of solar power technology and have installed solar panel systems in thousands of residential and commercial properties across South Africa. For more information about our industry-leading solar solutions, contact Solar 4 Life.