Applying durable energy sources such as wind- or solar energy is of significant importance in the transformation to a more sustainable energy supply. The unpredictable nature of these renewable energy sources however, is a big disadvantage. Given the fact that electricity is a commodity that needs to be consumed and produced simultaneously, an increasing discrepancy between supply and demand emerges. This results in energy infrastructure that is increasingly more difficult to stabilize and requires significant reserves in energy capacity to guarantee an uninterrupted supply of power.

Electrical energy storage can be used to store excess power generated by domestic rooftop PV systems, rather than exporting it to the grid and then buying back energy at a higher price. We have used one-minute PV generation and electrical load data from thirty-eight low-energy homes to simulate the operation of energy storage, and to calculate the impact on the amount and cost of imported electricity. The payback period for energy storage systems depends on factors including the cost of energy storage, the cost of electricity, the price paid for exported energy, the power generated by the PV system, and how and when energy is used by the household. We calculate the payback period for various configurations. Decreasing feed-in tariffs and the decreasing cost of energy storage will lead to an uptake of energy storage system over the next few years. While storage can be used to reduce household electricity cost, it does not lead directly to reductions in CO2 emissions. However, household energy storage will enable greater use of rooftop PV, and ultimately can be used to match household demand to variable supply from local and centralised renewable energy sources.

Goals
The project "Energy storage for households" aspires to store renewable energy at the site of the end user, resulting in an optimal stabilization of the energy infrastructure. By effectuating a high degree of autonomy in dedicated parts of Nieuw-West, we strive to achieve this goal.
When?
Early in 2014, the first batteries will be placed in a few selected households while the full-scale deployment will take place during a few years in project “City-zen”, starting in 2014.