Suitability of Loads for an Energy Management System
An important form of intelligent energy management is automatic load control. Without any compromises in convenience or supply reliability, the operation of suitable loads is rescheduled to times with high PV generation. To be able to benefit from these advantages, it is important to know which loads are suitable for operation in an energy management system:
Loads should be capable of consuming a significant portion of the locally generated PV energy. The higher the energy demand of load per day, the more worthwhile is the control of such a load.
Loads should be in operation either daily or on fixed days during the week.
Loads should be flexible with regard to time and should not be obliged to produce a specific result immediately after being switched on.
Examples of suitable loads
The following loads are particularly suitable for an energy management system - not least because they are flexible with regard to time:
A heat pump for provision of warm water requires 3 kWh to 5 kWh of energy per day and runs daily.
A washing machine requires 1 kWh to 1.25 kWh of energy depending on the program selected and it runs several times each week.
A dryer requires 1.5 kWh to 2.5 kWh of energy depending on the program selected and it runs several times each week.
A dishwasher requires 1.5 kWh of energy for each wash and typically runs daily.
A heating element for a hot-water tank requires 2 kWh to 3 kWh of energy per day and is in operation daily.
A charging station for electric vehicles requires 4 kWh to 22 kWh of energy per day to charge an electric vehicle depending on the individual driving profile and is in operation daily.
Examples of unsuitable loads
The following loads are unsuitable for an energy management system:
A desk lamp with an energy requirement of e.g. 20 Wh can only consume a very small portion of the PV energy.
Toasters and kettles are only switched on when they are required. Toast and hot water are required promptly.
An electric cooker is switched on when the user wishes to cook. The food is to be prepared promptly and not simply whenever sufficient PV energy is available for operation of the electric cooker.