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PV + BESS hybridisation

Your plant produces most when energy is worth least.

At midday the price drops to zero and your plant's capture price collapses. A BK battery shifts that output to the evening, avoids curtailment and, under RD 917/2025, without losing the regulated remuneration.

Assess my plantHow it works
PV + BESS hybridisation
Typical battery duration
2 h
Per Powerbolt container
5.015 MWh
Coupling in existing plants
AC or DC

The problem

Midday sun no longer pays.

With so much PV producing at the same time, prices in the solar hours collapse. Your plant sells a lot and earns little.

  • During solar hours the price falls to zero or below: your plant produces most exactly when energy is worth least.
  • The capture price of PV drifts further from the average market price every year.
  • Curtailment and limitations: when the grid or the price isn't on your side, output is cut and lost.
  • Without firm capacity, a solar-only plant cannot take part in the capacity mechanism.
of hours in 2024 had a price below €10/MWh.
26%
average capture price of PV in 2024.
~35€/MWh

Including two full months below €10/MWh.

of days in 2024 with a spread of more than €50/MWh between hours.
68%

That is the margin the battery captures.

additional revenue with a 2-hour battery in 2024.
+58.4%

BK historical simulation for a typical plant.

Source: BK analysis of Spanish day-ahead market prices (OMIE), 2024. Daily prices in Storage Analytics.

How a BK BESS solves it

Produce at midday. Sell in the evening.

The battery shifts solar energy to the hours when the system needs it and pays for it. BK EMS and the PPC decide when and how much.

  1. 01

    Charges with cheap sunshine

    Absorbs midday output and the energy that is currently spilled or curtailed.

  2. 02

    Sells into the evening ramp

    Discharges when the price rises, using price and production forecasts.

  3. 03

    Controls the point of connection

    The PPC respects the export capacity and the system operator's setpoints, with telemetry to REE where applicable.

  4. 04

    Opens new revenue streams

    Firm capacity for the capacity mechanism and reserve for balancing services.

without battery: sold at the captured pricePV plantSolar hoursEMS + PPCBK batterySoC81 %GridPoint of connectionMarketExpensive hoursA spring day in the marketchargedischargeprice ≈ €0/MWh00h06h12h18h24h
  • PV output
  • Market price
  • Battery discharge

Illustrative profile of a sunny day: the shape of the curve, not real prices. Check daily prices in Storage Analytics.

RD 917/2025, explained

Adding a battery no longer costs you your remuneration.

Royal Decree 917/2025 (BOE-A-2025-20694) amends RD 413/2014 to bring energy storage into the remuneration and technical framework for renewables.

Arts. 11 and 21

Get paid for all the energy generated

In hybrids without self-consumption, the plant is paid for all the energy from the renewable module, even when it goes to the battery. Equivalent hours are calculated using energy at the plant busbars.

Annex XV

Same dispatch priority

Renewables with energy storage now have the same priority as pure renewables. The concept of “non-dispatchable generation” disappears.

Type 3 hybridisation

Ro on busbar energy

Renewables + energy storage without self-consumption: operating remuneration is calculated on the energy generated at the plant busbars, not just the energy sold.

Art. 7 and AP 12

Telemetry and control centre

Energy storage above 5 MW (0.5 MW outside the mainland) must be attached to a control centre and send real-time telemetry to REE, with generation and storage reported separately.

  1. Oct 2025

    Redispatch priority

  2. 1 Jan 2026

    Remuneration and hybridisation

  3. 1 Jun 2026

    Control centres and telemetry

All in force. The decree does not create a dedicated remuneration for standalone energy storage: a standalone battery earns its living from the market and from mechanisms such as capacity. Summary prepared by BK; it does not replace the regulatory analysis of each project.

Curtailment, capture price and capacity

Three ways for the same plant to earn more.

Curtailment

Curtailed energy has value again

When the grid cannot take more energy or the price is zero or negative, the plant limits its output and that energy is lost. With a battery it is stored and sold later.

Capture price

Raises what you earn per MWh

It is the average price your plant earns, weighted by its output. Shifting two hours of production to the evening brings it closer to the average market price, or above it.

Capacity

Get paid for being available

The capacity mechanism pays for firm capacity. A solar-only plant has none at night; a hybrid plant does. In an illustrative BK example, the IRR rises from 1–2% (solar only) to 5–12% (hybrid with capacity).

How much does a battery earn in Spain today? Prices, spreads and revenue, updated daily.

Open Storage Analytics

Existing plants

Your plant stays as it is. The battery is added.

We hybridise plants in operation and at RtB stage. We choose the coupling based on your inverters, your point of connection and the energy you lose today.

AC coupling

Battery with its own converter

ACPV modulesPV inverterDC → ACBK batteryBK PCSAC ⇄ DCTransformer · POI
  • · Independent of the existing PV inverters.
  • · Can charge from the grid and provide balancing services.
  • · The most common option for plants in operation.

DC coupling

Battery on the DC bus

DCPV modulesBK batteryDC/DCDC busInvertersharedTransformer · POI
  • · Recovers the energy the inverter clips.
  • · Shares the inverter: fewer conversion stages.
  • · Requires inverters compatible with the DC/DC converter.

Permitting we handle

  • Update of the grid access and connection permit
  • Hybridisation application to the authorities
  • Simplified environmental permitting where applicable
  • Guarantees, licences and consumption point
  • Engineering, installation and commissioning with EMS and PPC

Recommended products

What we solve it with.

The full range

Powerbolt

3.34 – 6.25 MWh

20-foot containers with liquid cooling, designed for hybridising MW-scale plants.

View product
BKENERGIES

Cabinets

241–418 kWh

For small plants or to distribute the battery alongside each inverter station.

View product

Racks and packs

172–373 kWh

Bespoke integration in plant rooms or DC-coupled with the existing inverters.

View product
EMS · ONLINE72%

BK EMS + PPC

EMS · PPC · SCADA

Market strategy, point-of-connection control and telemetry to the system operator.

View product

References

We have already done it.

All projects

BESS hybridisation

Ocaña (Toledo)

5MWh

2 MW · 2,150 kVA

Your installation

We tell you which system you need and how it performs in your case.

Project data: type, location, energy, power and connection capacity.

Frequently asked questions

What people ask us before deciding.

Do I lose the specific remuneration if I add a battery?
No, if the hybridisation is done without self-consumption (type 3). Since 1 January 2026, RD 917/2025 recognises the energy generated at the plant busbars even when it goes to the battery. Before designing, we review how your plant fits the regulation.
Do I need a new grid access and connection permit?
RD 917/2025 makes it easier to keep your grid access and connection permits when adding energy storage, but they must be updated and hybridisation must be applied for. We assess each case and handle the permitting.
AC or DC coupling?
AC if you want independence from the existing inverters and the ability to charge from the grid as well. DC if you want to capture the energy the inverter clips today and share the conversion. We decide using your plant's data.
How many hours of battery?
In our hybridisation proposals we usually work with 2-hour systems: they balance investment, daily cycles and the price spread between midday and the evening.
Who operates the battery?
BK EMS, with price and production forecasting, in automatic or manual mode. O&M and 24/7 monitoring are handled by our team.
What if my plant is at RtB stage?
Even better: the battery can be built into the project before construction. We review access and connection, environmental permitting, guarantees and licences.

Do you own a solar plant?

Send us its hourly output and its point of connection. We'll tell you which battery fits, how to permit it and how much more it will earn.

Talk to our engineersView products