What are solar panel batteries, and what are they used for?

Thanks to these batteries, you can use stored solar energy during periods of low solar radiation, such as at night or on cloudy days. This results in greater autonomy, more efficient use of the energy generated, and a significant step towards energy independence. Additionally, solar batteries help reduce reliance on the electricity grid, which in turn lowers electricity bills.

How do solar batteries work? 

The operation of a solar battery is based on a charge and discharge cycle. During the day, solar panels capture sunlight and convert it into electricity in the form of direct current (DC). This energy is then stored in the battery via a charge controller, which prevents overcharging and protects the system. When night falls or solar production is low, the battery releases the stored energy to cover the home or business’s electricity needs during those hours. If alternating current (AC) is needed, the inverter converts the stored energy into usable electricity for everyday needs. Having an inverter also optimises self-consumption, improves the efficiency of the photovoltaic system, and reduces reliance on the power grid.

Key features of a solar battery 

Solar batteries have a set of technical characteristics that determine their performance, durability, and efficiency. Let’s explore the most relevant ones! 

Storage capacity 

This is the amount of energy the battery can store, measured in kilowatt-hours (kWh). The higher the capacity, the greater the autonomy of the system. 

Depth of discharge (DoD) 

This indicates the percentage of energy that can be used without damaging the battery. A higher depth of discharge means you can make better use of the battery’s total capacity. 

Life cycles 

This refers to the number of times the battery can be charged and discharged before its performance begins to decline significantly. The more cycles it supports, the longer its lifespan.

Energy efficiency 

This measures the amount of energy that can be recovered compared to the amount originally stored. A more efficient battery reduces energy losses and maximises the use of solar power. 

Charging time 

This is the time it takes for the battery to fully charge. Charging time varies depending on the type of battery and the power of the photovoltaic system. 

Types of solar batteries 

There are different types of solar batteries, each with specific characteristics to suit various energy needs and budgets. Let’s look at the most common types: 

Lead-acid batteries 

These are the most traditional and cost-effective option. They require regular maintenance and have a shorter lifespan, although they remain a valid choice for off-grid installations. 

AGM and gel batteries 

These are sealed lead-acid variants that require no maintenance. They offer greater safety and a longer lifespan. 

Lithium batteries 

Known for their high efficiency, long lifespan, and compact size. Although their initial cost is higher, their performance and minimal maintenance requirements make them a popular choice. 

Flow batteries 

These are typically used in large-scale installations due to their high storage capacity and long lifespan. However, their use in residential environments remains limited. 

Maintenance of low-consumption PV energy storage systems 

Battery maintenance depends on the type of technology. For example, lead-acid batteries require periodic checks of the electrolyte levels and terminal cleaning, whereas lithium or AGM batteries need little to no maintenance. It is important to monitor the charge level, avoid frequent deep discharges, and keep the system in a well-ventilated environment, protected from extreme temperatures.

Proper maintenance is key to extending the lifespan and ensuring the safe and efficient operation of the battery. 

Lifespan of solar batteries and solar energy storage systems 

As noted earlier, the lifespan of a solar battery varies depending on its technology (depth of discharge, number of cycles, etc.) and usage.

Generally, lead-acid batteries last between three and five years, while lithium batteries can exceed 10 years with proper use. Choosing a high-quality battery and following the manufacturer’s guidelines are essential for maximising long-term performance. 

Benefits of self-consumption with solar panels 

Self-consumption using photovoltaic batteries offers numerous economic and environmental benefits. Here are the most significant:

Savings on electricity bills 

By storing the energy generated during the day, you reduce the need to draw power from the grid, leading to substantial savings on electricity bills. 

Greater energy independence 

Batteries provide energy even during times without solar production, increasing autonomy and reducing exposure to price fluctuations. 

Sustainability 

Using solar energy helps cut CO₂ emissions and supports a cleaner, more responsible energy model.

Home EV charging

In single-family homes, you can install charging points for electric vehicles powered by the solar energy generated on-site.
This saves on fuel costs and maximises the use of the home’s solar installation —a practical method for optimising your home-generated electricity.

Endesa’s solar battery offering 

At Endesa, we offer more than just solar panels —we provide access to solar energy with no installation required. With the Tu Casa Solar Virtual plan, you can enjoy a monthly allotment of free kWh between 10:00 and 18:00, tailored to your plan size, with 100% solar-sourced energy.

Can’t install solar panels at home? No problem! This plan is designed for renters, those with technical limitations, or anyone who simply wants to avoid construction work. There’s no long-term contract, no administrative hassles, and a fixed price for three years —a practical, sustainable way to save from day one.

Additionally, you can add services such as reduced-price AC maintenance, access the PARA TI loyalty programme, and handle everything through the Endesa Clientes app. You decide how you want to save —we take care of the rest!