Perfecting battery design and chemistry has long been the focus of dedicated engineers from around the world.
For decades scientists have sought to improve the weight vs. energy capacity vs. life cycle ratio.
And they are succeeding.
Thus, it stands to reason that there are many different types of battery chemistries on the market today, all of which aim to be the next big thing within the energy storage market.
According to Yahoo News: "The Global Consumer Battery Market is expected to grow by $9.7 Billion during 2022-2026."
That's an increase in compound annual growth rate (CAGR) of 4.15%.
So, with so much funding, which battery types available are actually worthwhile looking at?
More specifically, which battery types of best for solar generators?
In this article, we aim to find out.
How many different battery types are there?
In order to keep this article relevant, it is important to note that we will only focus on secondary cells (also known as rechargeable batteries).
The reason for this is quite simple.
Solar generators are built using only rechargeable batteries. If they weren't, the technology would be redundant.
Finally, our list below will only include lithium-ion technology, as most mainstream solar generator brands only include this type of battery technology in their products.
Here is a complete list of rechargeable lithium-ion batteries:
Lithium-ion battery
- Lithium cobalt oxide battery (ICR)
- Lithium–silicon battery
- Lithium-ion manganese-oxide battery (LMO)
- Lithium-ion polymer battery (LiPo)
- Lithium–iron–phosphate battery (LFP)
- Lithium–nickel–manganese–cobalt oxides (NMC)
- Lithium–nickel–cobalt–aluminium oxides (NCA)
- Lithium–sulfur battery
- Lithium–titanate battery (LTO)
- Thin-film lithium-ion battery
- Lithium–ceramic battery
What makes an ideal battery?
How do you feel after reading that list of different battery types?
Exhausted?
We know it is a lot to take in. This is what we meant by "for decades scientists have sought to improve the weight vs energy capacity vs life cycle ratio."
We weren't joking.
And the above list is what they came up with.
Now, with that being said, what makes an ideal battery?
- Low maintenance
- High energy density
- Safe
- Slow aging process
- Hot and cold resistant
- Low self-discharge
- Lightweight
To date, lithium-ion technology comes the closest to meeting the ideal ration in all the aforementioned points above.
Which battery type is best for a solar generator?
Now that we know what makes an ideal battery, which battery would actually be the best for a solar generator?
Figuring that out can be somewhat difficult as we already know there are over 10 different types of lithium-ion batteries alone!
However, with that being said, the solar generator market has matured greatly over the last 5 years and most manufacturers are becoming privy to the best chemistries suited for solar generators.
Those chemistries are namely:
- Lithium–nickel–manganese–cobalt oxides (NMC)
- Lithium–nickel–cobalt–aluminium oxides (NCA)
- Lithium–iron–phosphate battery (LFP)
Below we have attached a comparative analysis of these 3 chemistries, thanks to this study listed on Research Gate.
In the above comparison, you can clearly see the pros and cons of each battery type. As you can see, all 3 chemistries are extremely similar when it comes to performance and specific power.
However, the differences can be seen (sometimes quite drastically) on the following points: Specific energy, life span, cost, and safety.
If you were to think about your own preferences, which points would be most important to you? What would you like to see in your solar generator?
At BLUETTI, we have already made our choice.
All our latest solar generators include an LFP battery as their energy storage solution.
For us, the most important details, in particular, are safety, performance, and lifespan, and we are willing to compromise on cost and specific energy to achieve these things.
(For those who are not aware of what specific energy is, it is simply the battery capacity in weight (Wh/kg. This essentially means LFP batteries will be heavier than, say, NMC batteries even when both have the same energy capacity.)
I bet there are many of you out there who could live with that, and perhaps you would prefer a heavier solar generator if it at least meant you had a safer solar generator.
However, what about the cost? How can we justify solar generators that are more expensive?
Well, this is an interesting one.
Cost is not always what it seems at first.
For example.
Let's look at two solar generators that have the exact same energy capacity.
One uses LFP technology, and the other uses NCA technology both have an energy capacity of 2,000 Wh.
The LFP solar generator costs $1,599, and the NCA costs $900.
Which one would you buy?
If you answered the NCA, you would be making a mistake.
The reason for that is the Levelized Cost Of Storage (LCOS). By taking the LCOS into consideration, you will have worked out the true lifetime costs involved.
Remember LFP batteries last much longer than NCA or NMC batteries.
Therefore, you need to take into consideration how long your solar generator will serve you for.
That same LFP solar generator for $1,599 has 3,500+ lifecycles, while the NCA generator only has 1,000.
So LCOS is in $/kWh. To find out the value, divide the price of the system by the overall storage capacity. To find the overall storage capacity, look at the life cycle for, e.g. 3500 cycles, and multiply this figure by the capacity of the battery in kWh.
That's your overall capacity. And you have the formula for LCOS.
So 3,500 cycles x 2kWh = 7000kWh. $1,599 ÷ 7000 kWh = $0.22/kWh
Now for the NCA solar generator.
1,000 cycles x 2kWh = 2000kWh. $900 ÷ 2000 kWh = $0.45/kWh
Final thoughts
Were you expecting that?
When taking into consideration lifetime value, we can see that the NCA solar generator is in fact 2X more expensive than the LFP solar generator.
Do not be fooled by the upfront costs. Always make sure to work out the LCOS in order to be sure you are getting the best value for money.
