How to Optimize Electric Water Heater Systems with Time-Based Price Scheduling
Electric water heater systems with accumulators can be programmed to operate during the hours when electricity is cheapest, resulting in significant cost savings. A new project demonstrates how to implement such a system that intelligently manages when water heaters activate based on electricity tariff data.
The system described works by analyzing electricity prices over a 24-hour period and selecting the three cheapest hours to operate the water heater’s resistance elements. This approach ensures hot water is available when needed while minimizing energy costs.
How the System Works
The electric water heater system features a short strike system with an electric motor that can operate for 3 to 24 hours at a time. The system is designed to maintain hot water by activating during optimal periods when electricity costs are lowest.
A key component is the thermostat that connects the resistance element when the water temperature needs to be increased. The system aims to schedule these heating periods during off-peak hours to maximize cost efficiency.
Monitoring System Indicators
The accumulator units include indicator lights that provide system status information:
- Green light: Indicates when the resistance element is active and heating water
- Red light: Signals potential issues like invalid expressions or lack of water
- Yellow light: Additional status indicator
For this particular implementation, only the green indicator is utilized, which activates when electricity is being supplied to heat the water.
Weekend Operation Mode
The system includes special programming for weekends when buildings may be unoccupied. On Saturdays and Sundays, it operates for just one hour to maintain minimum temperature levels until regular operation resumes on Monday. During weekdays, the system follows its normal pattern of activating during the three least expensive hours.
Real-Time Price Monitoring
The project incorporates data from electricity tariff tables that provide hourly pricing information. By analyzing this data, the system can identify price patterns and automatically select optimal operation times.
Testing confirmed that the system correctly identifies the cheapest hours from the pricing data. For example, when analyzing a 24-hour period, it successfully identified the 3-4 hour block as having the lowest price and the 9-10 hour block as having a higher price, matching the reference tariff table.
Implementation Process
The implementation involves creating an application that downloads and processes electricity price data. This data is structured in a consistent format that shows prices for different time blocks throughout the day.
The application identifies the three cheapest time periods and schedules the water heater to operate during these windows. This approach ensures that water is heated efficiently while minimizing electricity costs.
During operation, the water heater typically heats for 20-minute intervals with 40-minute rest periods, which is sufficient to maintain the desired water temperature while maximizing energy efficiency.
This automated system represents an intelligent approach to energy management, allowing building operators to optimize water heating operations based on real-time electricity pricing data.