Q1. The graph below shows a typical-day pattern of an electrical load demand and the respective wholesale market electricity price.

Figure Q1: Typical daily profile of an electrical load demand and the respective wholesale market electricity price.

a) Looking at the load in Figure Q1, identify the type of consumer (commercial, domestic, industrial). Explain the shape of the curve using typical consumer behaviour.

b) The system is on-grid and a flexible pricing strategy is offered by the electricity provider instead of a flat rate. The price for electricity goes up by 3p/kWh between 11 am and 2 pm and between 7 pm and 10 pm every day. What change in consumption pattern do you expect? Which DM side measure (after Gelling) would you associate with this change of the consumption pattern? Note: there is no energy storage considered at this stage.

c) The consumer wants to cover an amount 100 % equivalent to the load shown in Figure Q1 using PV and take the system off-grid. The rated power (kWp) of your PV array will be 12 kWp. Estimate the size of the energy storage technology necessary to run the system off-grid. Identify a suitable energy storage technology for the determined size and load demand in Figure Q1. State any assumptions that you make. d) Discuss the key operational parameters of your chosen energy storage technology from c) with regard to optimum energy performance and maximum economic gains.

7 Electricity Demand Price 5 Electricity Demand (kW) Electricity Price (centkWh) 3 N 2 0 18 20 22 24 46 8 10 12 14 16 Hour of the Day 7 Electricity Demand Price 5 Electricity Demand (kW) Electricity Price (centkWh) 3 N 2 0 18 20 22 24 46 8 10 12 14 16 Hour of the Day