A site with charging, generation, storage and a building management system has four things making decisions about the same electrical supply. Each optimises for its own objective, and together they can produce outcomes none of them intended.
Orchestration is the question of which one is in charge, and it is more often unanswered than answered badly.
Conflicting objectives
Charging wants to deliver energy to vehicles. Storage wants to charge when energy is cheap and discharge when it is expensive. Generation wants to be self-consumed rather than exported. The building wants its own loads served.
Left independent, storage may discharge to support charging that could have waited, or charge from the grid at the same moment generation is being exported. Both are individually rational and jointly wasteful.
One system must hold the site constraint
The supply limit is a single number and only one system can be responsible for keeping the site within it. Where two systems both believe they are managing it, they will occasionally both allow load simultaneously.
Naming the authority, and making every other system subordinate to its allocation, is the first architectural decision and the one that prevents the worst failures.
A workable precedence
Cost optimisation belongs last. Systems that place it higher produce sites that save money and occasionally fail to deliver what someone needed.
- Site safety limits, which nothing may override.
- Building critical loads, which are not negotiable.
- Contracted or tariff-driven constraints, such as a demand cap.
- Vehicle charge requirements by departure time.
- Cost optimisation, which uses whatever remains.
Timescales differ and that causes oscillation
Storage responds in seconds, charging allocation in seconds to minutes, building systems in minutes, tariff scheduling in hours. Systems reacting to each other's outputs at different rates can oscillate.
Damping, minimum dwell times between changes, and a clear direction of control rather than mutual reaction are what prevent that.
Measurement has to be shared and consistent
If storage and charging are each reading a different meter, or the same meter at different intervals, they will disagree about the site state and act on that disagreement.
A single authoritative measurement, distributed to whoever needs it, avoids a class of problems that are otherwise very difficult to diagnose.
Complexity has to earn its place
Every additional coordinated system adds integration, failure modes and diagnostic difficulty. A site with modest charging and no demand-based tariff may gain very little from orchestration and lose availability to it.
The question worth asking is what the orchestration is worth annually against what it costs to run. On many sites the honest answer is that simple independent operation is sufficient.