Electricity storage units with a grid-serving operation mode are often a prerequisite for state subsidies. What does this mean in detail? And why do most subsidy programmes require grid-serving electricity storage systems?

What does grid-serving mean?

The term 'grid-serving' is generally used when an individual or multiple systems such as generators, storage units and consumers contribute to a reduction in (electricity) grid costs. The term also incorporates the avoidance of grid bottlenecks and grid overloads and minimising the need for grid expansion. As a synergy, it saves costs on grid expansion and reduces disruptions in the electricity grid. Grid-serving benefits everyone. 

A grid-serving operation mode ensures, by controlling the connected systems, that the load on the electricity grid is distributed as evenly as possible. A similar amount of electricity is fed into the grid at any time of day. PV storage systems can make a significant contribution - as long as they support the grid-serving operation mode.

Electricity consumption and electricity production usually take place at different times.
Solar power storage systems compensate for this. Grid-serving operation also relieve the public grid.

How grid-serving electricity storage systems work

Photovoltaic systems represent a problem for the electricity grid. They always, depending on their location, generate their peak electricity at the same time: when the sun is shining and around midday. Unless this electricity were stored or controlled it would be fed cumulatively into the public grid leading to overloads. The solution: power storage systems. They store the electricity so that it is either not fed into the grid at all or at a later time.

However, even here we face a problem: the electricity storage units' capacity. Private household electricity storage units for photovoltaic systems have a limited storage capacity. Once they reach this maximum capacity, the electricity is automatically fed into the public grid. Hence, if the storage unit is "fully" charged at midday, a lot of electricity is again fed into the grid during peak hours and leading to grid overloads. To avoid this scenario, the storage unit should be charged during the time of maximum solar power generation. It means: the electricity storage system must have free capacity at midday.

The solution: the forecast-based charging method
for electricity storage units

How do you solve the above-noted peak hour problem? Through forecast-based charging of the electricity storage unit. A dedicated software calculates a yield forecast and links it to the expected consumption in the same time window. Based on this forecast, the storage system decides at which point in time charging the battery will lead to the best possible yield. On a sunny day, for example, the software 'tells' the storage system that it should only store at midday - and to ignore the first hours of sunshine in the morning. At the high-yield midday, the electricity storage system still has enough free capacity to store the self-generated solar electricity. It relieves the grid is at midday - and there is no high noon* scenario for the electricity grid.

*high noon = the most important or extreme period / exactly midday, when the sun is at its highest point in the sky 

Better for the grid, better for a long service life

RCT Power's PV storage units are, as a standard, preset to a forecast-based charging method as standard and thus support the grid-serving operation mode. They meet the state and federal subsidy criteria. There is another benefit: the electricity storage units are preserved, as they do not reach their capacity limits as often.

Our sales partners are happy to provide you with more information about our grid-serving electricity storage systems.