B · Utility-scale generation · Hybrid and BESS
Solar, batteries and engines in one plant
A hybrid plant uses solar as primary power, stores the surplus in batteries (BESS) and leaves to the engines the firmness solar cannot provide. A single control system decides, moment by moment, which source delivers the power.
How a hybrid works
Each source does what it does bestBy day, solar feeds the load and charges the batteries. As the afternoon ends, the BESS delivers the stored energy. When the battery reaches its limit, or when the load rises beyond what solar and BESS can carry, the gas or biogas engines start.
The result is a plant with solar primary power and the firmness of a thermal plant, in which the engines run fewer hours than in an engine-only plant. The design looks for the point at which every solar MW, every battery MWh and every engine pays for itself.
Where there is a grid, the hybrid can run connected to it; where there is none, it runs islanded as a microgrid.
When it is not a fit
- If the site’s grid supply is reliable, inexpensive and sufficient, and an outage costs little: a solar park with the grid may be enough.
- If there is no gas or biogas and the load needs firm power: the fuel has to be solved before the hybrid.
- If the load is almost entirely at night and there is no room for the solar it would take.
The role of BESS
What batteries do in a hybrid
More than storing energyShift energy
Store midday solar and deliver it in the afternoon and at night.
Ride through transients
Respond in milliseconds while an engine starts or a cloud passes.
Shave the peak
Cover demand peaks so the engines or the grid do not have to.
Fewer engine hours
Engines run less and at a better load point, with less fuel and maintenance.
Island stability
Help hold frequency and voltage when the plant runs without a grid.
Own backup
An intermittent plant that injects into the grid must have its own backup or pay for it (LSE art. 32).
Reference: Baker's Bay Golf & Ocean Club
Bahamas · 2020–2023 · EPC in a joint venture7MW
Capacity
Hybrid plant on an island
3× JMS420
Engines
Jenbacher
3MW / 3 MWh
BESS
Battery storage
150+GWh
Energy generated
Estimated to date
At Baker's Bay, the group took part in a joint venture to design and build a 7 MW plant that combines three Jenbacher JMS420 engines, solar PV generation and a 3 MW / 3 MWh BESS, to supply continuous power to a resort development on an island. It is the direct precedent for GIS Power’s approach: solar and BESS working as part of primary power.
Frequently asked questions
How much battery does a hybrid plant need?
It depends on the load curve, the solar resource and how many hours the engines should stay off. It is calculated during feasibility with the load’s hourly profile.
Can solar and BESS be added to an existing engine plant?
Yes, if the plant’s controls can be integrated and there is room for the solar. It is a way to cut fuel use without losing the engines’ firmness.
What batteries do you use?
We work with brand-authorized commercial partners, including Pylontech and Huawei for storage and power conversion, and INNIO Jenbacher and Guascor for engines.
How is a hybrid plant paid for?
With the same models as any plant: a power purchase agreement (PPA), energy as a service, BOOT, or a lease, a loan or cash, with terms of 48 to 180 months.
Let’s discuss your hybrid plant
Location, load curve and available fuel: that is where we start.
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