1. What is Cost per Watt?

Cost per watt is a metric that helps understand electricity expenses at a more granular level by breaking down the cost to power one watt of electrical load for one hour. It's particularly useful for comparing energy costs across different tariffs or regions.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• Cost/kWh — Your electricity rate in pounds per kilowatt-hour
• 1000 — Conversion factor (1000 watts = 1 kilowatt)

Explanation: Since 1 kWh equals 1000 watt-hours, dividing the cost per kWh by 1000 gives you the cost per watt-hour.

3. Importance of Cost per Watt Calculation

Details: Understanding cost per watt helps in:

• Comparing electricity tariffs more precisely
• Calculating operating costs for small electrical devices
• Budgeting for energy consumption at a granular level
• Making informed decisions about energy efficiency investments

4. Using the Calculator

Tips:

• Enter your current electricity rate in £ per kWh (found on your energy bill)
• For monthly cost calculations, multiply the result by the number of hours used and wattage of your device
• UK average electricity price is around £0.28-£0.34 per kWh (2023)

5. Frequently Asked Questions (FAQ)

Q1: Why calculate cost per watt instead of just using cost per kWh?
A: Cost per watt allows for more precise calculations for small devices and makes it easier to compare different wattage appliances.

Q2: How do I calculate monthly cost for a specific device?
A: Multiply cost per watt by device wattage, hours used per day, and days in month (e.g., 10W bulb × 5h/day × 30 days × £0.00034/W = £0.51/month).

Q3: Does this include standing charges?
A: No, this calculates only the unit rate. For complete cost analysis, include standing charges separately.

Q4: How accurate is this calculation?
A: It's mathematically precise for the unit rate, but actual bills may vary with VAT, discounts, or tiered pricing.

Q5: Can I use this for solar panel ROI calculations?
A: Yes, it can help estimate savings per watt of solar generation, though other factors like feed-in tariffs should also be considered.