Choosing the right solar battery for an off-grid installation: what factors need to be taken into consideration?

Choosing the right solar battery for an off-grid installation: what factors need to be taken into consideration?

In off-grid systems, solar batteries play a crucial role in ensuring the storage and availability of solar energy. However, choosing the right solar battery can be a challenge, as there are many factors to consider to ensure optimum performance.

Whether you’re a solar manufacturer or an OEM, this article will guide you through the key factors to consider when selecting the right solar battery for your off-grid system.

Technical factors to consider when selecting the right solar battery for an off-grid installation

Battery technology

Different solar battery technologies are available on the market: lead-acid, nickel-metal hydride (NiMH), lithium-ion and others.

In addition to their cost, each technology has its own characteristics in terms of resistance to external conditions, energy density and lifespan. Choosing the right technology therefore depends on a number of factors, not least the battery’s expected performance.

  • Longer life and high energy density: If your aim is to optimise the life of the battery, i.e. the number of charge/discharge cycles, you should opt for a lithium-ion solar battery, specifically Lithium Iron Phosphate (LiFePO4). This type of battery lasts 10 times longer than a lead-acid battery.In addition to their long life, LiFePO4 batteries also offer a high energy density, meaning the amount of energy that can be stored in the same volume is much greater. By way of comparison, a LiFePO4 solar battery has 3 times the energy density of a lead-acid solar battery.Today, LiFePO4 lithium technology is the most efficient in the solar energy sector and is used by Belios to design its Longlife solar batteries.


  • Tolerance to extreme environmental conditions: Off-grid solar installations are often exposed to hostile environmental conditions such as extreme temperatures, vibrations and high humidity. Choosing a solar battery with a good tolerance to these conditions helps to guarantee its reliability, performance and lifespan. This choice is all the more crucial when the solar installation in which the battery is installed is located in an isolated, hot or humid geographical area (countries in the Middle East, Africa, isolated regions, etc.). For example, the lifespan of a lithium-ion battery is divided by 2 to 3 when it is used at 45°C instead of 25°C.NiMH (nickel-metal hydride) batteries such as Belios Xtreme solar batteries are best suited to this type of installation. They are perfectly resistant to temperatures ranging from -25° to +80°, compared with lead batteries, which cannot withstand temperatures above +40°.

Charging and discharging efficiency

The charging and discharging efficiency of a solar battery is a key factor to consider. A high-efficiency inverter will convert more solar energy into stored energy, maximise the use of solar energy and reduce losses.

A solar battery is recharged via one or more solar panels. The energy produced by the solar panels is then transformed and stored in the battery using a solar charge controller, whose role is to optimise the amount of energy produced by the solar panel. There are two types of solar regulator: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracker), each with its own characteristics.

MPPT is the more advanced version and maximises the performance of a solar panel by helping it to operate at the ideal voltage to produce maximum power output. MPPT can increase the power extracted from the solar panel by between 30% and 40% compared with a PWM solar regulator.

This MPPT intelligence enables Belios to offer high-performance solutions. Each of our solar batteries is fitted with a S.L.I.M electronic board incorporating an MPPT module.

Energy management and battery safety

Some solar batteries are equipped with an integrated Battery Management System. This system monitors the battery in real time, in particular the temperature and voltage of its cells and its state of health. This prevents the risk of overcharging, excessive deep discharging and short circuits.

As a manufacturer of solar power systems, considering the presence of a BMS in the battery you select means you can be sure of a battery that is safe and has the functions you need for your solutions to work properly.

To meet this need, Belios integrates a BMS module into each of its solar batteries. This module contains intelligent software developed by our research department and adapted to each of our solar batteries.

Choosing a highly qualified solar battery manufacturer

Whatever the solar installations you need to power (solar street lamps, surveillance cameras, display panels, etc.), it’s important to entrust the design of your batteries to an industrial expert in solar energy.

This professional must be able to select the most appropriate battery technology for your needs and support you from A to Z to develop a high-performance, all-in-one solution.

All Belios batteries are designed in-house by a dedicated R&D centre. This enables Belios to meet all your technical requirements and to monitor the manufacturing process for your batteries right through to industrialisation (small to large series) in our factory near Bordeaux.

Specialising in solar energy, Belios benefits from the expertise of its parent company Neogy in the design of batteries and systems, as well as the expertise of the other companies in the Startec Energy group, to which it belongs: BMS PowerSafe for the development of BMS boards and Clairitec, an electronics design office.

Reach out a Belios expert to find out more about our support in developing your solar batteries.



Solar batteries: what are the differences between Lead-acid, Ni-MH and Lithium-ion?

Solar batteries: what are the differences between Lead-acid, Ni-MH and Lithium-ion?

Solar batteries play a key role in storing the energy produced by photovoltaic panels. These solutions allow energy to be stored for powering and autonomously operating solar installations: lighting, display panels, traffic lights etc.

Several technologies and electrochemicals can be used to design a solar battery. However, the most common solar batteries are made of Lead-acid, Ni-MH and very recently Lithium-ion.

Lead-acid solar batteries: a limited technology

lead-acid is an electrochemistry historically used for battery design. The lead-acid battery consists of lead and plastic plates that are immersed in an electrolyte, usually sulphuric acid. The lead and plastic plates form the positive and negative electrodes of the battery.

Advantages of lead-acid

  • Reliability: Lead-acid batteries are reliable and can last for many years when used and maintained properly.
  • Low cost: Lead-acid batteries are often the most affordable of the different types of solar batteries, making them more competitive for buyers looking for a low-cost battery.

Limits of lead-acid

  • Required regular maintenance: Lead-acid batteries require regular maintenance to perform optimally, which can be tedious and expensive.
  • Toxic gases: Lead-acid batteries can produce toxic gases when deep discharged, i.e. discharging more than 80% of their energy capacity, which can be hazardous to health and the environment.
  • Weight: Lead-acid batteries are heavy and bulky, which can cause problems for transport and installation depending on the space available.

Ni-MH solar batteries: A commonly used technology

Ni-MH (Nickel-Metal Hydride) is a battery technology that uses a metal hydride alloy as the anode material, nickel oxyhydroxide as the cathode material and an alkaline electrolyte to allow the circulation of ions.

This battery technology has been democratised over time to overcome the limitations of lead by offering a more efficient and durable alternative. Today, Ni-MH is widely used in solar battery design because of its advantages.

The strengths of Ni-MH

  • Adapted to extreme temperature conditions: The first feature of Ni-MH is its ability to withstand harsh conditions (between -25°C and +80°C). This feature allows solar batteries made with Ni-MH to be installed in humid or hot regions such as some countries in Africa, Asia or the Middle East.
  • Longer life than lead-acid solar batteries: Ni-MH solar batteries have a longer life than lead-acid batteries, which means they require less frequent replacement and provide optimal long-term performance when properly maintained.
  • Less maintenance required: Ni-MH batteries require less maintenance than lead-acid batteries, which can be an advantage in minimising costs.
  • Easily transportable: One of the major advantages of Ni-MH batteries is that they are very easy to transport by air, land or sea compared to other technologies such as lithium. Their transport is not subject to specific regulations as they are not considered “hazardous materials”.

Beyond their advantages, Ni-MH solar batteries are now competing with more modern and promising technologies.

Lithium-ion solar batteries: A promising technology

Compared to Ni-MH, the democratisation of lithium-ion in solar is more recent. Lithium-ion generally offers better performance than its lead and Ni-MH predecessors and can meet new needs in terms of solar energy storage.

Among the multitude of lithium-ion categories on the market, LiFePO4 (Lithium Iron Phosphate) batteries are the most widely used.

Strengths of LiFePO4 solar batteries :

  • High energy density: LiFePO4 batteries have a very high energy density, which makes them more efficient for solar energy storage. They have 3 times the energy density of e.g. lead-acid batteries.
  • Longer lifespan: LiFePO4 batteries last 10 times longer than lead-acid batteries without any loss in performance. They also last longer than a Ni-MH battery.
  • On-board intelligence: As with all lithium batteries, LiFePO4 solar batteries have an integrated BMS (Battery Management System) board. This electronic management board regulates the operation of the battery by optimising charging and discharging times, protecting it against various risks (overvoltage, short-circuit, undervoltage, etc.) and optimising its performance over the long term.

In conclusion, the choice of solar battery technology depends on the customer’s project needs. The Ni-MH solar battery is an effective solution for a solar street light in a hot area. However, to power an outdoor billboard that operates 24/7, the LiFePO4 battery is a preferred alternative due to its high energy density.

Belios assists manufacturers and equipment suppliers in selecting the most suitable battery for their needs and project. From customised design to industrial production: Belios develops your solar batteries.

Would you like to have more information about Belios solar batteries or entrust us with your project? Contact our specialists.