Commissioning, testing, and handover: When is the system ready for operation?

When an industrial BESS (battery energy storage system) stands finished on its foundation, with modules, switchboard, and cables in place, that is not the same as being ready for operation. The shift from installation to operation is easy to underestimate. It is both technical, because the system must be tested and approved before it may deliver electricity, and contractual, because a project here moves from being under construction to being in operation.

This article walks through that phase: the functional test, the communications check, the grid company's final approval, when market participation can begin, how any backup function is tested, and what the customer receives at handover. The physical preparatory work and the application to the grid company each have their own article in this guide, so the focus here is the last stretch before the system is in operation.

From physically complete to ready for operation

Physical installation means the hardware is in place. Ready for operation means the system has been tested, approved, and put into operation. Between those two states sits commissioning, and a battery cannot simply be switched on once it has been set up. Because it both draws electricity from the grid and sends electricity back, there is a chain of technical checks and formal permits that must be in place before it may do either. In that phase the chain is checked link by link, and responsibility gradually moves from a construction project to an operations agreement.

Functional test and communications check

The first link is a functional test of the system. Here it is verified that the modules, switchboard, and controls work together as planned, and that the system responds as it should to the commands it receives. It is a check that the physical installation is not only correctly mounted, but also works as intended.

Alongside the functional test stands the communications check. An industrial BESS is controlled and monitored via software, and several systems must therefore be able to talk to each other: the system must communicate with our monitoring system, and if the company has its own control system that the battery should integrate with, that connection must also be tested. Without a stable connection, the system can neither be monitored nor controlled correctly, and the communications check is therefore a separate item on the list of what must work before the system is ready for operation.

Grid company approval: meter, energisation, and permit

The link that most often decides when the system can actually be put into operation is the grid company's approval. The grid company is the local distribution system operator that owns and operates the local electricity grid. The approval follows a fixed sequence that the grid companies themselves describe, and it consists of several steps. The customer's electrical installer submits a completion notification for the system in the grid company's system and agrees a time for the electricity meter to be installed, after which the grid company allows the system to be energised and the meter to be fitted. The installer's completion notification is at the same time the customer's documentation that the work has been carried out in accordance with the law. A precondition is that the technical documentation has been submitted and approved by the grid company before the system can be put into operation.

The meter is a matter of its own. Because a battery both consumes and delivers electricity, the settlement meter must be configured for bidirectional metering before the battery may deliver electricity to the grid, so that both what the system draws and what it sends back can be measured separately. It is the electrical installer who arranges this in connection with the registration. The grid company must also have approved the submitted documentation before the battery may receive or deliver energy to the electricity grid. Metering is therefore not a formality after go-live, but a condition for feeding into the grid.

For a battery, an extra link sits on top of ordinary commissioning: a test phase. The grid company first grants a temporary grid connection permit, during which the system's technical properties are tested and documented, and only when the tests are approved is the final grid connection permit issued, after which the system is fully connected. The purpose is concrete: the test must ensure that the system does not affect the electricity grid and other customers negatively, because a system that does not meet the technical requirements can cause flicker for neighbours or, in the worst case, unintended outages. For the timeline, the point is that a system may only be used once a final grid connection permit is in place, which requires both documentation and testing. It is this step that marks that the system is technically ready for operation from the grid's side.

Market participation: a separate step after the tests

Once the system is approved for operation, the question of market participation arises: the commercial optimisation in which the system trades flexibility in the electricity markets. For a turnkey system with a minimum of two modules, we facilitate that part through an aggregation partner, and it can only begin once the technical tests have been completed.

Here it is worth being precise about what market access requires, and what we ourselves are. Access to the markets for system services (ancillary services that help keep the electricity grid in balance) assumes that the system owner collaborates with a balance responsible party or a system service provider, or alternatively becomes one themselves, and that the system is prequalified, meaning tested and approved by Energinet (Denmark's national transmission system operator), so that it meets the technical requirements for the relevant market. We are not ourselves a balance responsible party. Our role is to coordinate market participation through an aggregation partner that holds that role, while market access itself depends on prequalification and on the technical requirements for the specific market. There is therefore no access that follows automatically from the system having been set up.

That a specialised partner handles that part is linked to how a battery business looks in practice. Revenue from system services can rarely stand alone, and a robust model typically also includes the spot and intraday markets, where volume and price swings are larger. It is that kind of ongoing optimisation across markets that an aggregation partner carries out.

For a single module, which a company can purchase without the full package, the picture looks different. Here we deliver operations documentation, but not the full market package, and the customer handles market participation themselves. The two tracks are not the same.

Backup and critical loads: a function that must be tested

Some systems are designed also to function as backup for selected critical loads, often in combination with an STS (Static Transfer Switch), a component that can switch a critical load between two power sources. If that option is selected, an extra item belongs to commissioning: the function should be tested in practice, not assumed to work because it is installed.

The background is well known from the emergency preparedness field. Without drills and testing, the risk of faults and gaps in an emergency supply is high, and a system that has not been tested can in the worst case give a false sense of security, because it looks as if it is in place, but does not necessarily deliver when it must. A backup test at commissioning shows whether the design actually holds. The decision itself about backup, STS, and reserved capacity is a separate technical choice, which we cover from a production-security angle elsewhere in our material.

Handover: what the customer receives

When the system has been tested, approved, and put into operation, handover takes place. In our model, it coincides with the final part of the payment falling due at go-live. What the customer receives is three concrete things.

• Operations documentation: The customer receives the documentation that belongs with owning and operating the system, including the formal completion notification from the electrical installer, which is the documentation that the work has been carried out in accordance with the law.
• Access and a system in operation: The system is in operation and monitored by our system, and the customer as owner has access to the system on their site.
• One fixed contact person: Throughout the process, the company has had one fixed contact person with us, and it is the same person who knows the project when it moves into operation.

There is one point worth being honest about. Handover does not include a customer portal with login or a dashboard where the customer can follow the system in real time themselves. That is not part of what we deliver at commissioning today. Monitoring is an operations task we carry out through our own system, and contact goes through the fixed contact person.

ZynexGroup's approach to system assessment

We treat commissioning as a phase in its own right with its own checklist, not as a closing step that takes care of itself. We coordinate the functional test, the communications check, and the grid company's approval together with the electrical installer, and we only start market participation once the tests have been completed. What we can stand behind is that the system is only declared ready for operation when it has actually been tested and approved.

Limitations and preconditions

Commissioning includes factors that sit outside both our and the customer's control. The grid company's approval follows the grid company's own process, and there is no fixed date for when the temporary or final permit is in place. The setup and testing itself typically takes around seven days, but that is an indicative estimate for planning use, not a guaranteed date, and the overall timeline is described in the guide's article on the process from signing to go-live.

We can prepare and manage commissioning thoroughly, but we can neither set the grid company's time horizon nor guarantee a particular date for market start. Market access depends, as noted, on prequalification and technical requirements and therefore does not follow automatically with the system, and any backup function is only ready for operation if it has been tested. Those factors do not change that the system can be technically in operation, but they affect when the full value is available.

Overall perspective

A system is ready for operation once the chain from physically complete to operation is complete: a functional test, a communications check, a settlement meter set to bidirectional metering, and the grid company's approval, which for a battery includes both a temporary and a final grid connection permit. Only then can market participation begin, facilitated via an aggregation partner and dependent on prequalification, and any backup function is only ready for operation once it has been tested. At handover, the customer receives operations documentation, a system in operation, and a fixed contact person. A company that knows those steps in advance knows both what must happen before the system is ready for operation, and why a fixed date cannot be set for the last stretch.

Have the potential for your facility assessed

If you are considering an industrial BESS, commissioning is part of what becomes concrete as a project approaches go-live: what must be tested and approved, and when the system can begin to deliver. We use your grid connection, consumption profile, and historical consumption data for an initial assessment of whether there is a match, and for a data-based dialogue on how a path toward go-live would realistically look at your site. You are welcome to contact us here.