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1 Energy Storage History 

In 1600, when William Gilbert, an English physicist, made an extensive study of electricity and magnetism, separating static electricity from the lodestone effect, electricity was transformed from an abstract curiosity into thorough research.

Although Alexandra Volta subsequently invented the first voltaic electrochemical battery pile in 1800, this was not until the J.F. Daniell invented the Daniell Cell in 1836, that electrical energy was first used as a power source. Source: Energy Storage: A Brief History Paving The Way Ahead


2 What is a solar Battery 

A solar battery is simply a battery charged with energy from solar panels. There are lots of types – tiny to utility-scale. If you’re looking for smaller solar power solutions, for more information on solar batteries and other products check out Let’s go Solar

3 Shipping date of a solar battery 

In this article, we will talk about an important matter related to solar batteries and the date of manufacture.
The date of manufacture is very important and is something that the buyer must know if the matter is related to the batteries. As for whether the matter is related to the solar panel or the inverter, it does not matter.

The solar battery, like other batteries, is affected by time, and here we mean the ampere in addition to the battery, affected by the subject of storage, which must have certain conditions such as temperature and many who face a problem when he buys the battery, he is surprised after a while that the battery is over And she was out of service.

The question then is, does the solar battery have a certain expiration date like other products such as food, and how long is the battery life?.
The answer, of course, is yes, the battery has an expiration date that must be taken into consideration before purchasing the battery and for a limited life.

You must know that the solar battery must have a production date of no more than a year, and the battery cannot be stored for more than The reason is chemical reactions that occur inside the solar battery even if it is in the storage period.
The problem with the battery is self-storage. When you buy a battery that has a large stored period, you find that it has completely discharged and is practically empty.

The expiry date will have expired, so you should pay attention to this matter, which is the date the battery was produced before you buy it.

One of the main reasons for battery damage is the expiration date (production date) and there are other reasons that we will talk about later.

4 How to know the date of manufacture? 

On the surface of each battery, there is a serial number written on it the date of production of the battery as shown in these pictures
                    Solar battery
But the way this date is written varies from company to company, meaning coding date varies from one battery to another.
 For example, Panasonic Corporation and Japanese companies obscure the following coding
The coding is in the form of the following symbol consisting of 6 numbers and letters
date codeYYMMDD + shift indication letter 
for example 200512َA
20: year-2020
05; month-May
12: Day – 12
A: name of the factory section  


One of the most famous and oldest American companies specialized in manufacturing solar batteries, and it is considered the best batteries in the world.


The expiration date in this type of batteries and on American batteries, in general, can be determined by this way 

Shipping -date 
This code indicates the month and year when the battery was shipped out of the factory. 
LETTER stands for the month, A to L; (A=January, B=February, C=March, and so on); 
NUMBER is the last digit of the year.
  • A battery with “G5” on the negative.
  • G4” means that it was shipped around July of 2015.

Where can you find this code?

Trojan always puts the date on the negative electrode of the battery, above the electrode, not specifically on the top of the battery. So when you look at the negative electrode, you find the code written with a letter and a number as shown in the picture
Trojan battery

Varta batteries

For German Varta batteries, two numbers are written on the negative electrode, one from the top and the other from the bottom. The number from the top represents the week, as shown in the picture. The bottom represents the year.

So we now know that every company has a way to set the date of manufacture in a way of its own and therefore there is no fixed standard and if you know that then you must pay attention to the date of production when purchasing the battery to avoid buying an expired battery

5. The 3 Common Types of solar batteries

The types of solar batteries differ in terms of specifications and components and in terms of operating systems , the most prevalent and used types in terms of efficiency, quality, life span, and components are:

1- Gel batteries

This type of battery is more prevalent and used due to its efficient performance and the quality of its design in terms of making the gel material is the main component between the battery slices instead of the acid and other types.This type is preferred for those who have a lot of consumption.

2- AGM batteries

This type of battery is composed of lead strips and cotton fibers moistened with modified acid material. This type is characterized by its superior performance in terms of charging speed and discharge speed. This type is preferred for those who have a protection system or an operating system when the power is out or for those who have many uses and few operating periods

3-Tuples batteries

This type of battery is characterized by the amount of deep slow and slow charging life more than others as the battery consists of lead slices and an insulating material packed with cylinders or tubes that extend vertically from the top of the battery to the bottom of it to maintain a longer life of the battery and the material is insulated and the battery is packed with the modified acid between the slices Battery This type of battery is preferred for those who are economical and regular consumption due to its longer shelf life compared to other types of batteries.
type of solar batteries

4. Batteries are the heart of an Off-grid system 

Not All solar systems requires batteries, if your system is an on-grid system you don t need to store your energy because you can use it directly and you can bank the restof energy produced in the grid,but connecting to the grid is not viable you have to invest for solar batteris .

that s where batteries come in.

6. Key terms of solar batteries.

Here are some key terms you should understand when you picking up your batteries .

Capacity: The amount of energy the battery can store and supply to the appliances.( rate of discharge,function of voltage, and amp-hours)

Battery Bank : a group of batteries , wired together to work with a solar charge controller at a voltage (12v,24,48) and capacity (200 amp hours )

Voltage: Solar batteries are rated by voltage.

Lithium solar batteries for off-grid solar systems come in either 12V,24V,48Vols configurations.

  • Small systems : 12 volts batteries 
  • Larg systems ; 6 or 2 volts solar batteries for high amp-hour capacity.

Amp-hour: Solar batteries are rated in amp-hours (Ah) which means how much current they output over time.and this key is used to compare lead-acid capacity.

Kilowatt Hour (KWH) : This used to quantify  the total capacity for a given bank based on voltage and amper hour.

Capacity (WH) = Voltage * Amp hour

Example : 12V*200Ah=2400 Wh = 2.4KWH

Cycle: When the solar battery got charged and discharged this one cycle. the life time of a battery (is not the time given by the manfufacture (forexample a 4 years waranty)) but in the number of times a battery charge and discharg over the course of it s  lifspan .

Depth of charge (DOD): the amount of energy  pulled out of a battery during each charge/discharge cycle. 

for example a battery of 75% depth of discharge means you can  use 75 % of it s capacity before recharging .

Efficiency: Solar batteries are not 100% efficient but power is lost in the charge and discharge process.

  • Lead-acid batteries are 80-85% efficiency
  • Lithium Batteries are 95-98 % efficiency 


Sizing a Battery Bank properly for your system is a crucial ,what  you need not know is how much power you use on a daily basis( how many Wh or kWh per day  ) .so the battery bank depends on the quantity of  power you have to store .

Depth discharge , efficiency are also  factors you have to make an eye on when after accounting the capacity of your batteries . accounting the battery capacity helps the customer to save costs because if you don t know how much power u use per day make you installing more batteries while you are enough .

  • Adding old batteries ( led acid batteries ) to new one when you decide to expand your battery is not good idea , this work leads to aging your new ones ,you will notice this after the first year .

8. Calculate Battery Capacity 

When you make your calculus on how much power you use per day ( Total loads) then you have to calculate the capacity of your batteries :

Let s suppose we have :

A Lead-acid solar Battery

Total loads = 15kwh

  • inefficiency = 80% (1.2)
  • Discharge Depth = 50%(2)
  • the inefficiency of the inverter = 10 %(1.05)
  • Temperature factor( reduce battery capacity )  = 1.11

Capacity = 15*1.2*2*1.05*1.11=41.95 kwh.

And because solar batteries are rated by amp-hour :

  • 41.95/48V=874 amp-hours
  • 41.95/24 V = 1748 amp-hours
  • 41.95/12V=3495 amp-hours

The minimum capacity of the battery bank  41.95 kwh , and you need  more than that because your solar system generates power everyday .,




Top Reviews 


Panasonic- Japanese company 

  • Varta – German company 





Neptune Power Batteries

solar battries
Neptune Power Replacement Batteries meet and even exceed manufacturers specifications, Superior Design, High Quality, long-lasting working life 3-5 Floating time range, High-Quality ABS material Fire Resistant, The Latest Technology grid design and paste formulation, AGM high standard separators.
Every Battery shipment is tested to Guarantee Hi-Performance & Longevity. Our Batteries Feature high discharge design, wide operating temperature range, and long expected service life.
Neptune NT12180 12Volts 18 Amp replacement battery feature Valve-Regulated Lead Acid (VRLA) SLA Sealed Lead Acid Battery Technology, making them safe to operate in any position, near people and sensitive equipment.
Manufactured under Japanese Quality standard, Environment Certificated Plant and facilities with:
  • ISO 9001 for Quality Management Systems.
  • ISO 14001 Environment Management System (EMS).
  • Health and 14001 Safety Environment Standards certification.
  • Under UL (Underwriters Laboratories) certifying Quality and manufacturing processes.

Install your new NT-12180 Batteries in your device using the same original configurations and existing cables and connectors. Please check your battery for dimensions and Terminals prior to ordering as manufacturers may change requirements without notice.

Beware Of SLA Batteries Without UL, UR, CE & ISO Symbols To Guarantee Quality & Genuine Specification Certifications. All Neptune batteries Are Manufactured In our Certified ISO Factories To Our Specifications.

#8 The number of amperes that can be drawn from the battery

Depending on the battery capacity, for example, if the battery of 12 V with a capacity of 100 amperes and the discharge time is 10 hours, then :
100A* 1h = 100Ah
10A* 10h = 100Ah
5A * 20h = 100Ah
20A* 10h = 200Ah
10A * 20h = 200Ah
5A* 40h = 200Ah
It is not recommended to fully draw the current inside the battery until it is completely discharged, which leads to a decrease in the battery life


9.  Best 9 Solar battery Brands

How Do I Choose the Best Batteries For Solar?

Choosing the best battery depends on several variables, such as application, budget, and maintenance expectations (like regular maintenance and replacement interval). The smartest option of battery for your project will be decided by your living situation.

#1.Universal Power Group 



  • Battery cell Type: AGM SLA DEEP Cycle
  • Battery Voltage:12 V 
  •  Capacity: 100 Ah
  • 1 Year Warranty


  • Great value for small off-grid solar
    John H.

    I purchased 4 of these for a small, rarely used solar kit. I am pleasantly surprised by their reliability and consistent power. Four of these can run 100 watts all day, and I've pushed them up to over 1500 watts for 30 minutes without significant voltage drop. (After the 30 minutes at 1500 watts, the unloaded voltage returned to 12.9V, indicating surprisingly little drain from this activity.) They are large and heavy, but they are an excellent value for an AGM battery!
Excellent battery, excellent value. Hooked up to my 160 watt panel (30 amp charger) and works perfect. Just bought a second one. Have a 2000 watt inverter and can run a 700 watt microwave for camping with no effort.

#2 Renogy

I. Renogy Pure Gel Battery


  • Battery cell Type: Lead-acid
  • Battery Voltage:12 V 
  •  Capacity: 100 Ah
  • Deep Discharge Recovery


Good performing batteries for the money.

Colorado Sun These batteries are very heavy but seem to perform well. On my first solar experience, I went with these batteries after many hours of comparing price performance and other reviewers’ experiences. The only drawback is you must purchase them from Amazon or Renogy. Used or open box batteries are bad and don’t get warranted after their thirty-day guaranty. Renogy or amazon replace them if arrive badly with no questions. My initial impression is that they hold charge well and seem to perform in hot environments. Hopefully, they will do the same in the cold as I live in the Colorado mountains at 6k feet. I had to purchase twice the amount of these batteries than originally expected to keep my power on full time with ac and microwave toaster etc. (400 square foot cabin) my system is 2280 wats with 3300-watt full sinus wave single and 6600-watt dual phase inverter. Make sure you program renogy specific charging parameters in order to protect the life of these batteries. I hope I’ve made a smart investment in something. That will last 5- 10 years min. I will update as I’ve only had them operational for a few months.

luke 6 months in storage, no recharge, it still powers up and holds the charge.

#3.VMAX Solar


  • Battery cell Type: Lead-acid
  • Battery Voltage:12 V 
  •  Capacity: 125 Ah
  • Deep Discharge Recovery


Steve said: Just got my 3 batteries installed with 500W of solar. Everything is working perfectly. Batteries arrived at about 90% charged, and I didn’t use them until the solar was all hooked up and the charge reached 100%. I’m very happy with these. If I have any trouble in the future, I’ll update!

EDIT: Almost six months in, and these are still working great! I’ve had no issues whatsoever. I run our entire tiny house off of these batteries. That’s enough to run our lights, charge our laptops, run my CPAP, 3 fans, a water pump, charge phones, and a 12v fridge. With our current power consumption, we drain about 10% overnight (with 3 of these batteries). Anyone making their own setup should calculate out their own energy consumption, but I just wanted to give a reference point. I love these batteries. I’m very happy with them. I set them up and haven’t had to mess with them one time. Again, if any issues ever arise, I’ll update

Steve Anderson

Amazing battery! I’ve been using two of these for 2 years now on our camper with a modest 200W solar setup. I love the capacity and the price + FREE SHIPPING! I also read that AGM batteries charge faster than standard batteries, but I really didn’t believe it as I figured charging rate must be dictated by the device charging them rather than the battery itself, but I’m starting to think what I read is right. They seem to fully recharge faster than the standard RV deep cycle batteries I’ve used before. Not exactly the most scientific review at this point, just a gut feeling but so far that is good enough for me.

#4.Battle Born LiFePO4 Deep Cycle Battery

#5. Weize Deep Cycle AGM SLA VRLA Battery

#.6. Renogy Deep Cycle AGM Solar Battery

#. Renogy Lithium-Iron-Phosphate Solar Battery

8.Mighty Max Battery

#9. ExpertPower Deep Cycle Solar Battery

7. Renogy Lithium-Iron-Phosphate Solar Battery

10. VMAXTANKS Solar Battery

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