Planning the power requirements and conducting a power audit for an all-electric narrowboat is crucial to ensure you have enough energy to run all onboard systems. Here’s a step-by-step guide to help you:
List All Electrical Devices
Begin by identifying all the electrical devices you plan to use on the boat. This includes essential systems like lighting, heating, and cooking appliances, as well as any additional devices like laptops, TVs, and water pumps.
Example list:
- LED lights
- Fridge/freezer
- Induction cooktop
- Heating system
- Water pumps (freshwater, greywater)
- Inverter/charger system
- Laptops, phones, and other electronics
- TV, microwave, etc.
Determine Power Consumption (Watts)
For each device, find out the power consumption, usually provided in watts (W) or amps (A) at a specific voltage. If the device lists amps instead of watts, use the formula:
Watts = Amps X Voltage
Most narrowboats use a 12V or 24V system, but if using an inverter for AC devices, the devices will run on 230V (UK).
Estimate Usage Time (Hours per Day)
For each device, estimate how many hours per day it will be used. This will allow you to calculate daily power consumption in watt-hours (Wh).
Example:
- LED lights: 10W, used 5 hours per day = 10W * 5 hours = 50Wh/day
- Fridge/freezer: 50W, used 24 hours = 50W * 24 hours = 1200Wh/day
Calculate Total Daily Power Consumption
Add up the daily power consumption of all devices to estimate the total energy required each day in watt-hours.
Example:
- Total daily consumption = sum of individual devices’ Wh/day
Account for Inverter Efficiency
If using an inverter to convert DC to AC, account for the efficiency loss (typically 85%-95%). Multiply your total daily power consumption by the inverter efficiency factor.
Example:
- Total consumption = 2000Wh/day
- Inverter efficiency = 90%
- Effective consumption = 2000 / 0.90 = 2222Wh/day
Plan the Battery Bank Size
Choose a battery system (typically lithium-ion or AGM batteries). Batteries are rated in amp-hours (Ah). Convert your daily watt-hour (Wh) requirements into amp-hours (Ah) based on your system voltage using the formula:
Amp-hours (Ah) = Whatt-hours (Wh) \ System Voltage (V)
Example (12V system):
- 2222Wh / 12V = 185.17Ah/day
Choose a battery bank size large enough to handle your daily consumption, ideally with 2-3 days of autonomy for periods with no solar or shore power.
Incorporate Power Generation (Solar, Generator, Shore Power)
Solar Panels: Estimate daily solar energy production based on the panel rating (in watts) and average sun hours.
Generator or Shore Power: Calculate how often you'll need to recharge the batteries using external sources, considering their output capacity.
Perform a Power Audit
After planning the system, track actual energy use once the boat is operational. This can be done with power monitors or tracking systems that measure consumption and charge levels.
Example of Power Audit Process:
1. Monitor daily energy consumption over a week.
2. Compare against your estimates.
3. Adjust usage patterns or upgrade systems (e.g., more solar panels or larger battery bank) if consumption is higher than anticipated.
This process ensures that your electric narrowboat will have sufficient power, taking into account both generation and storage capacity.