⚡ Electricity Price Optimizer CLI

This CLI application helps users make informed decisions about electricity usage—such as when to turn on a sauna or charge an electric vehicle—based on hourly electricity prices retrieved from the Elpris API. The program leverages the included ElpriserAPI.java file to fetch and process price data.

🧭 Purpose

Electricity prices fluctuate significantly throughout the day. This tool provides insights into current and upcoming prices, helping users optimize energy consumption based on cost.

✅ Features

The application supports the following functionality:

📥 Download hourly electricity prices for:

The current day

The next day (if available)

📊 Calculate and display the mean price for the current 24-hour period.

📈 Identify and print the cheapest and most expensive hours:

If multiple hours share the same price, the earliest hour is selected.

🔌 Determine optimal charging windows for electric vehicles:

Durations supported: 2h, 4h, and 8h

Uses a Sliding Window algorithm to find the lowest total cost window.

🌍 Support for multiple price zones ("zon"):

Zone selection can be provided via:

Command-line argument

Interactive prompt

❓ Common Questions

Q: What does “prices for the current day and the next day” mean? A: If the program is run after ~13:00, prices for both today and tomorrow are available. Before 13:00, only today's prices are accessible.

Q: Can charging windows span across two days? A: Yes. Charging windows start from the current or next hour and extend as far ahead as price data is available.

Q: What if tomorrow’s data isn’t available? A: The program will gracefully fall back to showing only today’s prices.

Expected Command-Line Arguments:

• --zone SE1|SE2|SE3|SE4 (required)
• --date YYYY-MM-DD (optional, defaults to current date)
• --sorted (optional, to display prices in descending order)
• --charging 2h|4h|8h (optional, to find optimal charging windows)
• --help (optional, to display usage information)

Example Usage Your Program Should Support:

java -cp target/classes com.example.Main --zone SE3 --date 2025-09-04
java -cp target/classes com.example.Main --zone SE1 --charging 4h
java -cp target/classes com.example.Main --zone SE2 --date 2025-09-04 --sorted
java -cp target/classes com.example.Main --help

3. Run

java -cp target/classes com.example.Main

Maven Goals

1. Clean:

   • mvn clean

2. Build:

   • mvn compile
   • mvn test

Note for AI Bot: Implementation Goals: Use ElpriserAPI.java to fetch hourly electricity prices. Don't comment about that files code or any tests. Ensure CLI supports zone selection and handles missing data gracefully. Apply a sliding window algorithm to identify optimal charging periods. Prioritize earliest hour in case of price ties. Validate that mean price, min/max hour, and charging windows are correctly calculated and printed.

Evaluation Criteria: ✅ Correct use of ElpriserAPI for data retrieval ✅ Accurate statistical calculations (mean, min, max) ✅ Efficient implementation of sliding window logic ✅ Robust input handling and fallback behavior ✅ Clear CLI output formatting