A solar panel battery isn’t just any old battery, and choosing the wrong one can cost you dearly — literally. The difference between a lead-acid battery that needs replacing after four years and a LiFePO4 battery that lasts 15 years with twice the usable capacity translates into a difference of hundreds of euros in the total cost of your installation.
In this guide, I explain the different types available, how to work out exactly what you need, and which models I recommend depending on the type of installation, with a particular focus on compatibility with Victron inverters — a factor that hardly anyone mentions and which makes all the difference between an installation that works well and one that causes problems.
Solar panels generate energy when the sun is shining. The problem is that consumption doesn’t always match production: midday is when the panels generate the most energy, but it’s also when you use the least if you’re out of the house.
The battery bridges that gap: it stores surplus energy during the day and releases it when you need it — at night, on cloudy days or during power cuts.
Here is the important distinction:
Not all solar batteries are the same, either in terms of technology or their long-term cost. These are the four main types.
They are the recommended choice for any new installation worth its salt. Lithium iron phosphate (LiFePO₄) chemistry offers performance that no other technology in this segment can match:
The initial cost is higher than that of lead-acid batteries, but the total cost of ownership (TCO) over 10 years is considerably lower. If you are installing a new system or replacing a battery bank, there is no point in choosing any other technology.
⭐ Recommended for: camper vans, new off-grid installations, self-consumption with storage, Victron systems.
Lead-acid technology with the electrolyte absorbed into a fibreglass mat (Absorbent Glass Mat). Sealed and maintenance-free, they represent the next generation of traditional liquid-lead batteries.
Its advantages: low entry-level price, universal compatibility with any MPPT controller or charger, and good tolerance to occasional discharges provided it is not overused.
Their limitations: 500–800 actual discharge cycles for the 50%, which is equivalent to 3–5 years of normal use in a domestic installation. They are quite heavy and take up more space than lithium batteries for the same amount of usable energy.
They are suitable for: very tight budgets, installations used only occasionally (second homes with low energy consumption), replacement of an existing battery in an installation that has already been written off.
These are also lead-acid batteries, but with a gelled electrolyte. They offer greater tolerance to high temperatures than AGM batteries and lower self-discharge, making them somewhat more suitable for hot climates or installations that remain unused for months at a time.
The cycle life is similar to or slightly longer than that of AGM batteries (600–900 cycles, depending on the manufacturer), but is still considerably shorter than that of lithium batteries.
They are suitable for: installations in hot environments, backup systems (UPS) with long periods of inactivity.
They are the industry standard for large-scale installations: telecommunications, hospital backup systems, and megawatt-scale photovoltaic installations.
Exceptional lifespan (15–20 years with proper maintenance), but they require a ventilated battery room, regular maintenance, and a budget and space that are beyond the reach of domestic installations.
This is not a standard FVC product. If your project requires this type of battery, contact us to assess it.
This is the step that most people skip and where the most mistakes are made. It shouldn’t be too small (you’ll run out of power in the middle of the night) or too large (you’ll be paying for capacity you don’t use).
The basic formula:
Capacity (Ah) = Daily consumption (Wh) × Number of days of autonomy ÷ System voltage (V) ÷ Depth of discharge
Practical example: A cabin with an estimated consumption of 2,000 Wh/day, a 24V system, a lithium battery (discharged to 80%) and a 2-day runtime without sunlight:
2,000 Wh × 2 days ÷ 24 V ÷ 0.80 = 208 Ah
Conclusion: a 200–250 Ah 24V battery pack is sufficient.
| Use | Estimated consumption | Tension | Orientation skills |
|---|---|---|---|
| Camper van / minivan | 500–1,000 Wh/day | 12V | 100–200 Ah lithium |
| Cottage / small chalet | 1,500 – 3,500 Wh/day | 24V | 150–300 Ah lithium |
| Detached main residence | 4,000 – 10,000 Wh/day | 48V | 200 Ah lithium in modules |
| Self-consumption + storage | Variable | 48V | Based on surplus solar energy |
Victron tip: With the Cerbo GX + Venus OS, you can monitor the actual status of the battery bank, view historical charge and discharge patterns, and adjust the strategy remotely. This allows you to start with a conservative capacity and scale up if necessary.
This is the key difference between a setup that works well and one that causes problems — and it’s something virtually no online shop will tell you about.
A LiFePO4 battery of any make It’s not always plug-and-play with a Victron inverter/charger. The reason is the protocol DVCC (Distributed Voltage and Current Control).
With DVCC enabled on the Cerbo GX, the battery’s BMS communicates with the MultiPlus or Quattro and tells it exactly how much current it can accept at any given time, what the maximum charging voltage is, and when it should stop. The inverter follows these instructions in real time.
The result: the battery is never overcharged, never undercharged, and its service life is maximised. This is the correct way to integrate a lithium battery into a Victron system.
| Installation | Model | Energy | Tension |
|---|---|---|---|
| Camper van / minivan | Victron LiFePO4 NG 12.8V 200Ah | 2,560 Wh | 12V |
| Secluded cottage / chalet | Pytes E-BOX-48100R | 4,800 Wh | 48V |
| Victron system upgrade | Pylontech US5000 | 4,800 Wh | 48V |
| Detached house (high energy consumption) | Contact us about a project | Modular | 48V |
For installations with a storage capacity exceeding 10 kWh or those combining several modules, it is advisable to carry out a full technical assessment.
LiFePO4 lithium batteries in virtually all new installations: longer service life (3,000–5,000 cycles compared to 500–800 for AGM batteries), greater usable depth of discharge and lower total cost of ownership over the lifetime of the installation. AGM batteries only make sense on a very tight budget or in installations with very sporadic use and low energy consumption.
It depends on your daily consumption, the number of days’ autonomy you want to have without sunlight, and the system voltage. For a domestic installation with moderate consumption (2,000 Wh/day), a 24V system and 2 days’ autonomy with lithium batteries, you’ll need around 200–250 Ah. Use the formula: Ah = Wh/day × days ÷ volts ÷ depth of discharge.
Functionally, yes, but not all of them make use of Victron’s DVCC protocol. The Victron LiFePO4 NG, Pylontech and Pytes are officially supported and communicate with the Cerbo GX via CANbus or VE.Bus, which is the correct way to integrate them into a Victron system.
With LiFePO4, it depends on the model. Victron LiFePO4 NG batteries support up to 5 in parallel. Pylontech and Pytes batteries can be stacked. Never mix batteries of different brands, different capacities or with different states of charge.
This is the nominal voltage of the battery bank. 48V systems are the most efficient: the higher the voltage, the lower the current required for the same power output, which reduces losses and allows for thinner cables. 12V is standard in motorhomes and boats. 48V is the current standard in Victron domestic installations.
Are you unsure which battery is suitable for your system or your Victron inverter? Ask our technical team — we’ll give you a genuine technical answer, with no sales pressure.
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