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How to Choose the Right Battery for your Solar System?

Table of Contents

Solar Battery is useful, but not saving money every time.

The battery bank in a solar system is always used to store excess energy for consumption at night or on rainy days. Sometimes, the battery bank could also be a back-up power supply to keep the whole system running.

It depends on your actual demand, and your desire.

Do you really need Solar Battery?

In general, there are three types of solar systems, on-grid, off-grid, and hybrid. The inverters used in these three types are different, so please pay attention to the differences.

On-Grid Solar System

When more power is generated than consumption, the excess power is fed directly into the grid. Oppositely, we get the power from the grid.

Theoretically, an on-grid solar system does not need any batteries.

On-Grid Solar System

Recently, Feed-in Tariffs (FIT) reduced. A lot of people choose to build their own battery banks for daily consumption to reduce electricity bills, which is a good choice.

But if your solar system is on-grid, and the FIT is good, it is not necessary to add a battery bank.

Off-Grid Solar System

Because of the isolation from the grid, the off-grid solar system is a small, independent system. All required energy must be from its own. So the battery bank should provide sufficient energy, or a backup power source such as a generator will be required.

Off-Grid & On-Grid

Since solar energy is highly affected by the weather and sunlight, wind and solar hybrid system is also recommended.

In an off-grid solar system, the battery bank is very important, even more important than the solar panel array.

Battery Bank is very important for an off-grid solar system.

Hybrid Solar System

Here hybrid solar system refers to on-grid and off-grid hybrid, not wind-solar hybrid.

Hybrid Solar System

The biggest advantage of a hybrid solar system is that if the grid fails, we will still have our own electricity to use.

Hybrid solar system is ideal for areas where the grid is not so stable. If the grid is uninterrupted and nearly perfect, then a battery backup system does not seem to be necessary.

Unless there are important devices that are not allowed to be off. It works similarly to a UPS system.

Commercial, Residential, and Vacation Cabin

Most commercial solar systems are on-grid because the energy is consumed at the same time as the energy is produced, which is during daylight hours.

Commercial Solar System

For residential use, we usually choose solar to save money on electricity bills or go for clean energy for eco-friendly purposes.

In the first case, the solar system could be also called an “investment”. Depending on local weather conditions and policies, we will need to calculate how long it would take to pay back the cost of the whole solar system. After that, all the earnings are benefits.

If it’s the second, it’s all about how much you can afford, how much you want to take. I know a number of friends who enjoy a renewable energy system purely for its own sake.

If it’s for a vacation cabin, and it is far away from the grid. As a small off-grid system, a battery bank is necessary.

Considering the fact that we only go there on vacations, no time for maintenance, low frequency of use, Deep Cycle AGM batteries (A type of Sealed Lead Acid Battery) are probably the most preferred option.

Vacation Cabin

Would you like to spend time on your Solar Battery?

The most traditional battery-flooded lead-acid batteries require regular maintenance and add water. It needs maximum maintenance.

It means we need to spend a lot of time and effort, but of course, outsourcing to a professional is a good option.

VRLA Deep Cycle batteries will work for 3-5 years, require voltage and damage check. Only a few time will be required, much less than flooded batteries.

With a lower budget, deep cycle AGM battery is recommended.

LFP (LiFePO4) batteries could save a lot of time and effort, it will enable you to concentrate more on your career and family.

LiFePO4 is the safest option in lithium technology. With a much better cycle life, it is widely used in a huge range of applications. Especially, the “blade battery” developed by BYD, can withstand pinprick tests without burning.

There are some integrated solutions from famous brands such as TESLA, the battery can be used as a common household appliance, requiring no maintenance. It is a beautiful, wall-mounted type that requires very little room. The only thing is, it is still expensive.

TESLA PowerWall

Relatively, a lower-cost solution is the 12V, 24V LFP battery, designed as a drop-in replacement for VRLA battery. It is a very nice alternative to the original lead-acid battery replacement.

Solar Battery Selection for Different Scenarios

Residential

12V LFP Battery

The most cost-effective battery in the long-term, expected to work for 10 years or more.

Drop-in replacement for lead acid batteries.

SYNERTAC 12.8V200Ah LFP Battery

Reowned All-in-One Solution

No maintenance, good-looking, only expensive.

SONNEN POWER WALL

Deep Cycle AGM Battery

Still, for a lot of families, deep cycle AGM battery is stable and affordable.

SYNERTAC Deep Cycle AGM Battery

48V Modular LFP Battery

SYNERTAC LFP48V100Ah

Off-Grid Solar Project

Here we are referring to projects with large energy storage demand, such as 96V, 110V, 220V, higher voltages, and capacities of 1000Ah, 5000Ah, 10,000Ah, and more. (MWh)

2V Industrial Battery
OPzS Battery Bank
OPzV Battery Bank

Solar Battery Selection for different electricity consumption

The following is just for example, one cycle per day, without considering rainy days and other conditions.

Typical household Monthly 300kWh

Equals to around 10 kWh per day, TESLA 10kWh, or LFP12V200Ah*4, or Deep Cycle AGM 12V200Ah*8 (50% DOD) are recommended.

Except for the wall-mounted type, all require a small battery rack with a space about 0.5m*0.5m.

Monthly 150 kWh

Equals to 5 kWh per day, Sonnen 5kWh, or LFP 12V250Ah*2, or Deep Cycle AGM 12V200Ah*4.

Monthly 600 kWh

In short, double as 300 kWh. 🙂

Vacation Cabin for light or charge only

One battery of 12V200Ah, could be good enough.

Or 24V100Ah, 24V200Ah for occasional use.

Advantages and Disadvantages of different types of Solar Battery

CostLifetimeDODLabor
Sealed Lead Acid Battery
12V LFP Battery☆☆☆☆☆☆☆☆
All-in-One Lithium Battery☆☆☆☆☆☆☆☆☆☆☆☆
Flooded Lead Acid Battery☆☆☆☆☆

Sealed Lead Acid Battery (Deep Cycle AGM Battery)

With reasonable prices and stable performance, deep cycle AGM battery is still the most popular choice for a lot of customers.

The shortage is, for the developing economy, its cycle life is not as good as lithium battery.

12V LFP Battery

12V LFP Battery is a type of LiFePO4 battery using Lithium Iron Phosphate technology, considered to be the safest li-ion battery.

LiFePO4 is more chemically stable, and it is incombustible, which means that it is not prone to thermal runaway, remains cool at room temperature. It can also withstand high temperatures without decomposing, and it is not flammable.

All-in-One Lithium Battery

Good-looking, only expensive.

Flooded Lead Acid Battery

Best cost-worthy, but it takes too much of the maintenance.

Conclusion

If it’s about saving money, in the long run, saving effort, saving time, LFP battery is definitely the best choice. Of course, it may be over your budget, then AGM deep cycle battery is also good, only the lifetime will be relatively short, 3-5 years to replace.

Flooded Lead Acid Battery is probably the first choice for professionals, regardless of maintenance expenses, the relative cost is the lowest.

Thank you for reading, I hope it helps. If you have any questions, please leave your comments below.

Andy
Andy
Hi, I’m Andy. Since the year 2015, I’ve been working in SunOn Battery, a manufacturer in China that makes various batteries for 15 years now. The purpose of this article is to share with you the knowledge related to batteries and energy storage solutions from a Chinese supplier’s perspective.

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