How can I upgrade a system that includes a PELD with a battery/Cabinet?

With the Upgrade Project feature in Helios, installers can easily analyze the value of upgrading an existing PV system with a battery or battery cabinet.
However, systems that already include a PELD require special attention. Due to technical limitations, a PELD cannot remain in place in most upgrade scenarios.

This article explains the supported upgrade scenarios and the correct technical approach for each case.

Summary of upgrade scenarios

Scenario 1: Adding an AC-Coupled Cabinet to a System With an Existing PELD

Upgrading with an AC-coupled cabinet captures energy that would otherwise be lost due to export limitations. A PELD changes how energy flows and, in most cases, prevents the cabinet from charging from the excess solar power.

Case 1A — Inside the Netherlands (NL Regulation)

In the Netherlands, installing an AC-coupled cabinet requires an EMS controller. The EMS monitors live consumption, determines when export is about to occur, and increases cabinet charging to absorb surplus energy. With a PELD, export is limited before the EMS can react, so excess energy never reaches the cabinet. To resolve this, a PELD must be removed, and all on-grid inverters should be connected to the EMS controller, which then manages export limiting.

Case 1B — Outside NL (EMS not required by regulation)

Outside the Netherlands, an EMS controller is often optional. Cabinet charges based on measurements from its own external meter. When a PELD is present, it removes all excess PV production before it reaches the meter, preventing the cabinet from detecting export or charging. Even if local rules do not require an EMS, replacing the PELD with an EMS controller ensures accurate export limiting and proper cabinet charging.

Scenario 2: Replacing On-Grid Inverters With Hybrid Inverters + Battery

This upgrade involves replacing existing on-grid inverters with hybrid inverters that include a battery. Hybrid inverters are not compatible with external PELD devices, so any external PELD must be removed. Hybrid inverters handle export limiting internally and must be connected in parallel to ensure proper coordination. Note: only hybrid inverters of the same series and power can be paralleled. 

Combining different inverter types can make system design complex. It is strongly recommended to contact Autarco for case-specific validation before installation.

Scenario 3: Adding a hybrid inverter as a retrofit to a system with Autarco on-grid inverter(s)

For systems where hybrid inverter is added to an existing Autarco system with on-grid inverter(s) and a PELD, export limiting can be realized in two different ways 

Case 3A — Leaving a PELD 

PELD is designed to communicate and limit the power of the on-grid inverters, but not the hybrid inverters. Whenever a hybrid inverter is installed as retrofit, the already installed PELD can keep limiting the power of the on-grid inverters but not the hybrid. It means that the minimum export that can be achieved will no longer be 0 W, but equal to the max output power of the hybrid inverter. Therefore this solution is suitable for sites where there is no 0-injection requirement. Note: Considering no PV is connected to the hybrid inverter, the export of the hybrid inverter can be controlled by periods of battery discharge. This approach can achieve 0-injection but needs extra consideration and is not recommended whenever there is strict 0-injection requirement. 

Case 3B — Installing an EMS system instead of a PELD

In order to realize full export control and to make sure 0-injection limitation is possible, EMS system is recommended. EMS controller can communicate with the on-grid inverter(s) and hybrid inverter at the same time making sure the whole system works in the most efficient way within the set boundary conditions.

Summary

In most scenarios, the PELD cannot remain in the system. Inside the Netherlands, the EMS controller replaces the PELD’s export-limiting function, while outside the Netherlands, replacing the PELD ensures accurate cabinet charging. Hybrid inverters manage export internally. Correct planning and adherence to these rules are essential for a successful upgrade. Autarco support is available for project-specific guidance.