14 juni 2026
Thousands of Dutch households are installing battery systems to store solar energy, respond to dynamic electricity tariffs, and participate in flexibility services. In response to this many emerging technologies are being researched. But here is an uncomfortable question: how do we actually know these batteries will do what was promised, or calculated? The short answer is, we don’t, at least not under the conditions that matter.
When a battery manufacturer publishes a datasheet, the numbers come from controlled lab tests using constant charge and discharge cycles. That tells you something, but it does not tell you how the battery behaves when your solar panels are producing unevenly, when a dynamic tariff signal tells the system to charge and discharge several times per hour, or when the grid operator asks it to respond within seconds for frequency regulation. This also applies to a lack of readily-available non-safety focused testing facilities for batteries.
This gap has real consequences. A battery rated for a certain capacity at constant load may deliver significantly less under the irregular patterns of an actual home. Efficiency drops, degradation accelerates unpredictably, and response times that look good on paper fall short under dynamic conditions. For homeowners, this means uncertainty. For researchers and grid operators, it means no reliable way to compare products on equal terms.
As part of my graduation project at Entrance, within the national BatteryNL research program, I set out to develop a battery test methodology that bridges this gap. The goal was to create a structured and repeatable way to evaluate any residential battery system under realistic operating conditions, regardless of its manufacturer or chemistry.
The starting point was a thorough analysis of existing international standards. What I found confirmed the problem: the main performance standard does not even include a test category for self-consumption, the most common way Dutch households actually use their batteries. Safety standards are well developed, but the industry does not yet have a reliable way to test whether a battery performs as needed in practice.
The methodology I designed is built around three groups of tests, ordered by data dependency. Baseline tests run first and establish the fundamental reference values: demonstrated capacity, round-trip efficiency, internal resistance, thermal behaviour, and more. Dynamic response tests come next, using those baseline values to define their power commands, measuring how quickly and accurately the battery follows step changes and continuous dispatch profiles. Finally, composite tests combine outputs from both groups into an overall health score and other performance parameters.
This modular structure means that even the baseline group alone produces a meaningful characterisation. Each additional group adds depth without invalidating earlier results, and future researchers can extend the methodology without redesigning what already exists.
Individually, one of the most valuable parts of this project was the proof-of-concept validation on the existing test bench at Entrance, a Pylontech battery paired with a Victron inverter. The real system immediately revealed things that no amount of desk research could have predicted. The battery’s power limits turned out to be asymmetric between charge and discharge. The battery management system had current thresholds that affected when it would actually respond to commands. The increasing heat of summer introduced its own unique challenge, that many would not expect the Dutch weather to provoke.
These discoveries directly shaped the final instrumentation and layout recommendations for Entrance’s new containerised test facility. Without running the actual tests, we would have designed around assumptions instead of evidence.
The energy transition depends not just on installing more batteries, but on knowing what those batteries can actually do. This methodology gives Entrance the ability to independently evaluate any battery that enters the lab and determine its suitability for specific flexibility services: from peak shaving to frequency regulation. As BatteryNL continues to advance battery technology in the Netherlands, having a reliable and realistic way to test these systems is a necessary foundation, and arriving at this deliverable hopefully advances it.
A blog by: Jose Pujol Freire, fourth year student of Electrical Engineering
Participated in the Learning Community Hydrogen
