Storage
PV + BESS

Optimize Your PV + BESS projects and operations

Solar energy storage is reshaping how solar power is valued on electricity markets and how grid stability is maintained. By storing excess solar energy in batteries, utility-scale solar power plants can shift generation to peak demand hours, maximize revenues, reduce reliance on the grid and minimise imbalance costs. Battery energy storage systems (BESS) coupled with solar panels have therefore become a cornerstone of renewable energy strategies.

Optimize the management of your Solar Energy Storage

Accurate sizing and forecasting is the key to unlocking the full benefits of BESS (Battery Energy Storage System) and maximizing returns on investments.

Accurate sizing of the BESS system and solar forecasting integrating on-site data

To financially benefit from battery storage, PV developers, traders and operators need accurate sizing of the BESS system and solar forecasting integrating on-site data. Sizing the storage capacity, dispatching or selling stored energy at the right time, maximising battery lifespan and minimising the cost of solar battery operations, all depend on a precise understanding of solar power output.

Forecast-driven dispatch optimizes when, how much, and how often solar energy is injected or stored.

Avoid unnecessary deviations driven by forecast errors
Optimize BESS cycling (when to charge/discharge, depth of discharge – DoD)
Avoid low-value or parasitic cycles driven by forecast uncertainty
Extend battery lifetime while maximizing value per cycle (arbitrage, peak shifting)

Aggregators and traders: market commitments and dispatch

Traders & aggregators need a clear view of aggregated electricity generation to commit firm volumes on Day-Ahead and intraday markets, and to avoid exposure to negative prices during PV surplus hours. Reliable forecasts enable to dispatch stored energy with confidence, contain imbalance penalties and capture the volatility of intraday electricity prices.

In regions exposed to strong grid imbalance penalties or rapid weather transitions, anticipating sudden drops in solar power output (monsoon periods, tropical climates) is key to securing portfolio-level commitments and maximising the effectiveness of storage solutions. Storing excess solar electricity to release it at peak demand is an effective strategy, but it depends on accurate anticipation of generation, and clear-sky days and variable days call for very different positioning approaches.

Plant Operators: Piloting BESS

Plant operators are responsible for the day-to-day operation of solar-plus-storage assets, typically through their Energy Management System (EMS). They must respect manufacturer warranties on solar batteries, which usually cap usage at 1.5 to 2 cycles per day, and manage Depth of Discharge (DoD) carefully. For example, eight small cycles at 10% DoD do not impact battery life the same way as one cycle at 80% at equivalent energy throughput. Unexpected drops in solar generation can force aggressive charging and discharging cycles that result in a shorter lifespan and lower efficiency.

NEXT probabilistic forecasts help planning battery operation while respecting cycle and DoD constraints. INSTANT adds a high-accuracy 30-minute forecast layer, particularly suited to challenging weather conditions, hydrogen electrolysis applications, and markets with strong grid imbalance penalties. By anticipating sudden drops in solar power output at the sub-hourly horizon, it reduces imbalance penalties (OPEX impact), protects battery lifespan and preserves the long-term performance of the installation (CAPEX impact).

BESS for H2 Electrolysers

In contexts such as hydrogen electrolysis coupled with PV + BESS, the requirement on short-term forecast accuracy is even higher: electrolysers operate within strict power ranges and rely on stable, well-anticipated power injection.

Developers and Investors: Sizing PV + BESS Projects

Developers and investors must size solar energy storage systems with long-term profitability in mind. For example, the choice between a 2-hour and a 4-hour battery depends on the temporal distribution of solar electricity generation, while project bankability requires confidence in the asset’s economics across multiple climate scenarios. Under- or over-sizing the storage capacity can compromise both profitability and battery lifespan over the 20 to 25 years of plant life.

FUTURE, our Solar Resource Assessment solution based on a one-year on-site measurements campaign relies on extensive GHI and meteorological data collection at 5-minute resolution. It enables to build a precise Typical Meteorological Year (TMY) and forward-looking energy production scenarios over 20 to 25 years. This level of detail supports sizing decisions that remain profitable across all scenarios considered, ensuring that the storage capacity is matched to the actual solar resource and to expected peak demand patterns. By characterising the temporal distribution of solar power generation with precision, FUTURE also informs the choice of cycling strategy, balancing warranty compliance, revenue maximisation and battery longevity. It allows developers to anticipate the cost of solar battery investments, optimise the kWh effectively stored and dispatched, and secure the long-term performance of hybrid PV + BESS power plants.

Our related resources

Accurate forecasting is the key to unlocking the full financial benefits of solar investments and maximizing returns on every grid-connected solar power system in the portfolio.

Numerical weather prediction models (NWP): The 131-million data point engine behind your weather forecast

Understanding solar energy potential across all time horizons

Industries: what are the solutions for energy independence?

Storage and PV: what opportunities?

Probabilistic Forecasting Methods for Solar Energy

Solar Data Forecasting Models: Transforming Weather Inputs into Accurate Energy Predictions

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Frequently Asked Questions

What is a solar energy storage system?

A solar energy storage system captures excess electricity produced by solar panels during peak generation hours and stores it for later use. The most common solution today relies on batteries (typically lithium-ion) but other technologies such as pumped hydro, compressed air, flywheel, thermal energy storage or molten salt are also used at utility scale. By storing solar energy, these systems decouple production from consumption, allowing electricity to be delivered at night, during cloudy hours or at peak demand. This flexibility is essential to integrate clean energy into the grid, reduce reliance on fossil fuels and lower carbon dioxide emissions. Combined with accurate forecasting, solar battery storage maximises the efficiency of every kilowatt produced.

What are the different types of solar energy storage systems?

Several types of solar energy storage coexist on the market. Lithium-ion batteries, including lithium iron phosphate (LFP), dominate residential and commercial installations thanks to their high energy density, efficiency and lifespan. Sodium-ion batteries are emerging as a safer, lower-cost alternative for grid-scale applications. Lead-acid batteries remain a legacy option for backup power, while flow batteries offer long-duration storage for utilities. Beyond electrochemistry, pumped hydro, compressed air, flywheel and molten salt thermal storage (notably in CSP plants) support large-scale grid energy storage. CalibSun’s forecasting services are technology-agnostic and constantly adapt to market evolution, ensuring optimised dispatch whatever the battery chemistry or storage technology deployed on a given asset.

What are the advantages of solar battery storage?

Solar battery storage transforms an intermittent, weather-dependent power source into a controllable energy asset. By storing excess electricity during peak production and releasing it at peak demand, batteries allow operators to maximise self-consumption, increase savings through favourable tariffs (such as NEM credits), and avoid exposure to negative prices on wholesale markets. Storage also provides backup power during blackouts, supports grid stability and enables higher penetration of residential, commercial and utility-scale solar. From a broader perspective, steering solar generation through storage is a turning point for achieving carbon neutrality objectives: it reduces reliance on fossil fuel power stations, lowers environmental impact and accelerates the transition toward sustainable energy systems.

How to avoid blackouts while using only solar panels and BESS?

Avoiding blackouts in a solar-plus-storage configuration requires precise anticipation of power output variations. Sudden drops in solar generation (caused by cloud cover, storms or monsoon transitions) can destabilise supply if storage and backup resources are not activated in time. CalibSun has developed INSTANT, a nowcasting service delivering highly accurate 30-minute GHI forecasts dedicated to power drop detection. By anticipating short-term variations, INSTANT enables intelligent control of complementary power sources (BESS dispatch, fossil fuel backup, hybrid generation) to maintain continuous electrical supply. This approach secures critical activities, protects customers from blackouts and maximises the reliability of solar-dominated energy systems.

Storage PV + BESS