What are batteries for photovoltaic installations?
2025 is proving to be a key year for energy storage. Globally, BESS (Battery Energy Storage Systems) capacity grew by more than 15% in 2024 according to SolarPower Europe, with Spain leading renewable integration: over 50% of electricity produced already comes from renewable sources (REE, 2024).
The PNIEC 2024 sets ambitious targets for 2030: up to 22 GW of storage in Spain, an essential step for the stability of the power system. In this context, batteries have become a critical and strategic element for households, companies and industries alike.
Solar batteries
Solar batteries are storage systems that accumulate the surplus energy generated by a photovoltaic installation. When solar panels produce more than is consumed (such as during the central hours of the day), this energy is not lost: it is stored for use at night, on cloudy days, or when demand increases.
Types of batteries according to technology
- Lead-acid (AGM, Gel, stationary): more affordable but with a shorter lifespan (600–2,000 cycles) and higher maintenance requirements. This technology is becoming increasingly obsolete in large-scale industrial projects.
- Lithium (LiFePO4 or LFP): more efficient, durable, and with a greater depth of discharge (up to 100%). They can last up to 10,000 cycles and have a lifespan of 15–20 years. With high thermal stability and low degradation, they are ideal for intensive industrial applications, offering an excellent balance of energy density, safety, and long-term performance. Currently, lithium is the dominant material in many applications, from mobility to residential and industrial storage, although promising alternatives like sodium are being explored.
- Sodium: a new technology undergoing significant R&D investment. Sodium is emerging as a promising alternative for stationary industrial storage batteries due to its abundance, low cost, high thermal safety, and strong performance in extreme conditions.
The year 2025 has marked a turning point with various industrial advancements and functional prototypes validated in real environments. Chinese manufacturer CATL, a global leader, has achieved energy densities close to LFP (up to 200 Wh/kg) and operability down to -40 °C.
What are they used for?
Batteries provide much more than storage:
Safety
- Energy autonomy: they allow solar energy consumption when there is no production, significantly increasing the self-consumption rate.
- Supply stability: they can act as a backup system in case of power outages (with the installation of a differential switch that enables island mode operation).
- Protection against price fluctuations: they reduce grid dependency and help balance time-of-use periods. Thus, the battery acts as a buffer against sudden tariff increases, such as those triggered by conflicts like Ukraine.
Profitability
- Consumption optimization: instead of selling surplus energy at low prices (during daytime hours), it is stored for use at night when prices are higher.
- Energy trading: beyond self-consumption, smart batteries make it possible to leverage grid price differences to generate savings or even income.
- Peak shaving: they can reduce peak demand by using stored energy during critical times.
Grid stability
The massive penetration of solar generation poses challenges for grid operators. Unlike conventional power plants, photovoltaic installations do not provide inertia or passive frequency regulation.
In this context, industrial batteries with grid-forming inverters are key: they can generate and sustain the frequency pattern autonomously, strengthening resilience and supply quality.
Who are they recommended for?
- Companies and industrial facilities with demand spikes and energy needs outside of solar hours
- Energy communities that share power
- Homes with high nighttime consumption
- Areas with frequent power outages
- Consumers committed to sustainability
Are they profitable?
Yes—especially in contexts with high energy consumption, variable tariffs, or demand peaks. Their economic viability improves with falling prices and institutional support.
- Payback period: between 5 and 8 years, depending on consumption and energy costs
- Lifespan: up to 20 years (for well-maintained lithium batteries)
- Return on investment: daily and sustained returns. The higher the electricity price, the better the ROI
- Subsidies: there are specific grants available, such as those offered by the IDAE
Isn’t a traditional generator better?
They are different solutions. A generator can supply energy for long periods and regardless of the weather, but:
- It has high maintenance costs
- It remains idle most of the time
- During general blackouts, renting one may be difficult or impossible
- In contrast, a battery:
- Operates continuously throughout the year, consistently contributing to savings
- Perfectly complements solar installations by maximizing performance and reducing grid dependence
Battery types: basic or smart management?
Most batteries currently installed in solar systems are lithium (LiFePO4), due to their efficiency, durability and safety. Within this technology, they can be classified according to the level of energy management they include:
- Batteries with BMS (Battery Management System): basic management of safety and internal cell balancing.
- Batteries with BMS + EMS (Energy Management System): advanced management with functions such as peak shaving, load shifting or energy trading.
Hybrid configurations
AC coupling: the battery is connected through its own inverter on the alternating current side. This approach provides great flexibility for expanding existing systems, as it allows adding a battery to a PV system without modifying the original solar inverter. It also makes it easier to integrate various sources (PV, wind, diesel generators) into the same AC bus. The main drawbacks are a slight loss of efficiency due to additional DC/AC and AC/DC conversions, and a higher upfront cost. It is very common in retrofits and in commercial and industrial applications.
DC coupling: in this case, the battery shares the direct current bus with the PV modules, usually through a single hybrid inverter. This configuration reduces energy conversions, achieving greater overall efficiency and better performance in storing solar surplus. It also allows better control of charging and discharging directly from PV generation. However, it is less flexible for expanding existing systems and requires strict compatibility between the battery and inverter. It is the preferred solution for new residential installations or projects where efficiency is a priority.
Standards and safety
BESS systems include protections against overcharging, short circuits and thermal management. They comply with international standards (IEC, UL) that ensure reliability and safety.
Noise
In commercial and industrial environments, noise levels are generally negligible compared with other factors such as efficiency, cost and safety. In urban settings, however, it may be a consideration.
Lithium battery price evolution
Lithium-ion battery prices have plummeted over the past decade thanks to economies of scale and improvements in both chemistry and manufacturing processes.
This drop has significantly improved the return on investment, making batteries more accessible and profitable.
The chart is based on data from BloombergNEF’s Battery Price Survey, which publishes annual trends in average lithium-ion battery pack prices, and historical aggregates from Our World in Data:
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BloombergNEF Battery Price Survey: data from 2010 to 2022, with the global average BESS pack price per kWh (e.g., 137 USD/kWh in 2020)
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Our World in Data – “Lithium-ion battery pack prices”: estimates and projections through 2024 based on BNEF and other industry reports
Key takeaways
- Lithium batteries have become the standard for industrial projects; lead-acid batteries are reserved for specific uses or very limited budgets.
- The BMS ensures safety, while the EMS maximizes profitability. Both systems are complementary.
- A price drop of up to 90% since 2010 makes BESS investment today a strategic and profitable option for industry.
Real success story: construction sector company
A company specializing in earthmoving, demolition, and infrastructure projects decided to electrify its heavy vehicle fleet to reduce its environmental footprint.
The challenge was significant: high costs due to demand peaks, a limited local electrical grid, and highly volatile electricity prices.
To address this, they implemented a smart energy storage and management system with:
- A 200 kW battery with 430 kWh capacity
- A 119 kWp solar PV installation
- Four charging points for electric vehicles
This solution allowed the company to:
- Maximize solar self-consumption
- Reduce costs from demand spikes
- Sell excess energy to neighboring businesses
- Provide grid stability during peak hours
The project improved operational efficiency, reduced emissions, and created a new revenue stream.
A clear example of how a well-designed energy strategy can transform the way energy is consumed and produced—even in demanding industrial settings.
The added value of Solventa6
At Solventa6, we design and install custom battery-based self-consumption systems with a comprehensive vision and a 100% client-focused approach:
- Direct and personalized service, no intermediaries
- Turnkey projects for individuals, companies, and communities
- Specialists in safety systems like Tigo’s Rapid Shutdown
- Full support: subsidy applications, legalizations, and permits
- Smart monitoring of energy production and consumption
Integrating batteries into a solar installation is both a technical and strategic improvement, bringing benefits in efficiency, savings, and energy independence—tailored to each user’s needs.
