Frequently asked questions

The Dutch electricity grid

Electricity is a flow of electrons. Electrons are invisibly small particles with a negative electrical charge. When an electrical device is turned on, the electrons flow through the parts of that device. This gives the device the energy it needs to work.

Electrons always flow from a place where there are many electrons to a place where there are few electrons. They move in a circuit. If the circuit is broken somewhere, the current cannot circulate. And an electrical device can only work if this circuit is closed.

It works the same way with the electricity grid, the electricity must be balanced.

The electricity grid is the grid that distributes electricity across the Netherlands. Electricity is generated in a power station, such as a coal-fired power station, a solar park or a windmill. The electricity is then transported across the country via high-voltage cables and converted into electricity that we can use at home in a distribution station and transformer houses.

Liander conveniently explains how the electricity grid works in a (Dutch) video:

We are producing and using more and more sustainable energy in the Netherlands. The demand for space on the power grid is therefore growing explosively, as a result of which the power grid is becoming (temporarily) full in more places. This means that in some grid areas, the load can be so high at certain times that the maximum capacity of the grid is reached. This results in that power cannot always be supplied or used, but also that no new sustainable energy projects can be connected.

December 2022, the national and regional governments, network operators, ACM and market parties presented the National Grid Congestion Action Program to create more space on the power grid in every possible way. This can be done by upgrading the electricity grid faster, stimulating smarter use of the electricity grid with new regulations, encouraging more flexible energy consumption and making use of large-scale battery systems that can store energy.

Due to the tight capacity on the electricity grid, we have to work together on solutions for a stable and reliable grid. Grid operators in the Netherlands are working hard on strengthening cables and building and expanding distribution stations. With TPStorage we too contribute by using battery systems for energy storage.

Energy storage

There are different types of battery systems. Currently, lithium-ion batteries are mainly used to support the electricity grid. In principle, these battery systems work like a very large battery, such as those in an electric car.

Of course, control techniques, cooling, inverters and safe housings are added to make the battery system operational.

The battery systems used by TPStorage mainly serve to support the electricity grid. They are charged one or more times a day and then deliver back. It is therefore not the case that a battery can store the energy in the summer and return it in the winter.

Sustainable energy is being generated in abundance in the Netherlands, but this has the effect of causing strong fluctuations on both the supply and demand sides because electricity from wind and sun is difficult to control. For this reason, well-functioning energy storage is important, since energy storage can keep the energy network in balance and thus prevent congestion on the electricity grid. Storing electricity to guarantee flexibility on the grid is therefore possible with battery systems.

Most battery systems are between 1 MWh and 200 MWh. If a battery system of average size, for example 20 MWh, is fully charged, that is enough to power more than 2,000 average households for a day.

EOS, BESS and BOS are abbreviations for large-scale energy storage systems. In the Netherlands we usually use the term EOS.

EOS: Energy Storage System

BESS: Battery Energy Storage System

BOS: Battery Storage System

The batteries in the system will last about 15 years, as will the inverters, and they will then need to be replaced. The installation must therefore pay for itself in that time. In principle, the permits are issued for an indefinite period, but every 15 years we check together with the network operator and other stakeholders whether the system is still useful and profitable. There may already be better solutions by then, and certainly there will be better battery systems on the market. That way we regularly have the opportunity to use the most modern systems.

No subsidy is granted for batteries, so these are projects that we carry out entirely at our own expense and risk. For the time being, it is still unclear what the business case for this type of system looks like and whether it will yield a stable return in the long term. So for the time being there is too much risk for external investors. However, there are regular opportunities to participate in projects of our sister company TPSolar via the website

The construction of a battery installation takes about 6-8 weeks on average. First, the foundations are poured and trenches are dug for the underground infrastructure. Then the container systems and transformers are placed with a crane, after which everything is connected. Before the system is put into operation, everything is extensively tested.

Energy storage technology

Liquid-cooled batteries have pumps and fans, but these are used only temporarily and produce little noise.

The manufacturers of the battery systems provide sound reports showing that the noise is barely audible even at close range.

Battery systems are constructed differently and therefore have different dimensions. As a rule, a battery unit is no larger than a 40-foot (12.2 x 2.44 x 2.59 meter) container.

Depending on the size of the total system, different containers are put together. In addition – depending on the manufacturer – smaller units are required for the auxiliary systems.

In addition, safety distances must be maintained (at least a strip of 4 meters must be kept clear) and maintenance corridors must be constructed.

The main risk of a lithium-ion battery based battery system is overheating of the cells, almost always due to a manufacturing or assembly error. Extreme overheating can lead to a chemical reaction in which a fierce fire breaks out and a lot of smoke is released. As a result, adjacent cells also overheat and a chain reaction can occur (thermal runaway) resulting in a fire in a large part of the battery container. In extreme cases, the released gases can also explode (in case of insufficient ventilation). The power of these explosions is relatively limited.

Battery systems built years ago have been known to experience fires and explosions. Today’s systems from leading suppliers are therefore protected on multiple levels, both preventive and reactive. For example, all separate battery modules are extensively tested before installation, the container is divided into several separate fire compartments, each compartment has sensors for temperature differences and smoke, and each compartment has two separate built-in extinguishing methods (extinguishing gas and water). The batteries are also cooled and the containers are made in such a way that any fire or explosion remains inside the container.

Due to the new technologies of battery systems, fires in energy storage systems hardly ever occur. In the event of any calamities, which we do not assume, TPStorage BV is responsible.

TPStorage takes as many measures as possible to prevent a fire. Battery systems are placed at a sufficient distance as much as possible so that the chance of a possible fire spreading is smaller, cabling is flame-retardant and if a fire breaks out in a battery system, it will also remain within that system due to the flame-retardant housing. In addition, fire safety is discussed with the local fire brigade (e.g. emergency exits, accessibility to the park, fire extinguishing water supply).

Large-scale energy storage is still new in the Netherlands, but many years of experience have been gained abroad. Legislation in the Netherlands is still somewhat behind. Of course, every installation must in any case comply with, for example, the Building Decree and the NEN standards. But a draft has now been published of extensive rules for large battery systems: the PGS 37-1 guideline. It is expected that this guideline will be included as a legal requirement by the end of 2023. For example, this directive contains rules in the field of safety; including minimum distances between installation components and to the environment, detection, alarm and extinguishing systems to be used, procedures for installation and maintenance, etc.

All our systems already comply with PGS 37-1.

There are fixed procedures for maintenance. This is of course necessary for safe and proper operation, but also to comply with the warranty conditions of the manufacturer and the permit requirements. TPStorage uses local parties as much as possible for this. All parts of the installation are linked via the internet to a control center where they are monitored 24 hours a day. In the event of (suspicion of) malfunctions, the right party can then be called in immediately to take a look on site.