Batteries
Users can add two types of batteries to ETMoses: a home battery and a larger scale neighbourhood battery. Home batteries are also available in the Energy Transition Model and the number of home batteries installed in the local energy scenario will be imported in the LES. Neighbourhood batteries are not yet available in the ETM and can therefore only be added in ETMoses. When scaling a LES back to a national energy scenario, the neighbourhood batteries will be ignored.
Batteries can be used to store electricity and supply this electricity at a later moment in time. Batteries are controlled through various Strategies. The remainder of this section is dedicated to the technical parameters of batteries in ETMoses.
Experts from Alliander stated that a battery system with a storage volume of around 10 kWh are currently the norm. We have based the battery in the ETM and ETMoses on a commercial-off the-shelf system is provided supplied by Wholesale Solar, which has a storage volume of 9.6 kWh at a cost of around EUR 6000.-. This system includes all necessary accessories and is basically plug-and-play.
All other specifications can be found in the P2P node source analysis on ETDataset-public.
The neighbourhood battery is a P2P storage technology which is located somewhere higher up in the network (typically not at the level of residences). A neighbourhood battery typically has a larger storage volume than a home battery. At the moment we assume that the neighbourhood battery has a capacity of 10 kW and a storage volume of 100 kWh. The other specifications are still being researched, but the user can adjust them to his own insight.
The main functions of a neighbourhood battery are:
- Balancing supply and demand by storing electricity in times of excess production and discharging in times of demand
- Preventing congestion of the transformer(s) and cable(s) of which it is a descendant node
The properties of the P2P technology serve as the starting point. The most important ones:
- Capacity (charging/discharging) [kW]
- Volume [kWh]
- Investment costs [EUR]
- Technical lifetime [years]
A new one:
- The fraction of the battery which should be reserved for congestion management [kWh]. If this is set to 20%, the battery cannot be discharged further than 10% and cannot be charged further than 90% for the purpose of 'balancing'.
The battery will actively charge or discharge to return to a state between the limits set by the user. So, if a congestion management event has discharged the battery to 5% full with the above setting of 20%, it will actively charge to 10% if no further congestion occurs and if doing so does not result in congestion. If no excess electricity production is available, the battery will use electricity from the grid.
The maximum value for the slider setting is 100% when the battery will charge up to 50% and then never balance anymore but only react to congestion. If there is no more congestion to compensate, the battery will return to being 50% charged.
Let's assume time steps of 1 hour for simplicity.
Consider the following setup:
During this time step the following happens: The battery discharges 4 kWh, the wind turbine produces 1 kWh, the grid will provide the remaining 6 kWh. The battery will not discharge completely because 1 kWh has to remain for congestion management (the slider is set to 20%, so in total 2 kWh of tis volume is reserved for congestion management).
Similar to Example 1 but without wind production and with only 1 kWh in the battery:
During this time step the following happens: The battery will discharge its 1 kWh of charge to prevent congestion of the trafo. The grid can supply the remaining 10 kWh to satisfy demand and the trafo can just manage. If the network permits it, the battery will be charged to 1 kWh in the next time step.
Similar to Example 1 and 2 but without demand:
The battery will charge its maximum (capacity limited) of 5 kWh to balance demand and supply. The grid must absorb the remaining 6 kWh.
