How to estimate daily kWh needs for an off-grid cabin?

Calculating Energy Requirements

To estimate the daily kWh needs for an off-grid cabin, start by identifying all the appliances and devices that will be used. Make a list of the wattage of each device, including lights, refrigerators, freezers, water pumps, and space heaters. Add up the total wattage of all the devices to get the total daily energy requirement in watts. Then, divide by 1,000 to get the daily kWh needs. For example, if you have a refrigerator that consumes 100 watts, a freezer that consumes 150 watts, and four lights that consume 9 watts each, the total daily energy requirement would be 100 + 150 + 36 (4 x 9) = 286 watts. Dividing by 1,000, the daily kWh needs would be 0.286 kWh.

Considering Peak Hours and Energy Storage

Another factor to consider when estimating daily kWh needs is the peak hours of energy usage. Typically, energy usage peaks during the evening hours when devices are in use. To account for this, you may want to increase the estimated daily kWh needs by 10-20%. Additionally, if you plan to store excess energy generated by your solar panels in a battery bank, you will need to consider the storage capacity and the depth of discharge (DOD) to ensure that you have enough energy stored for nighttime use.

Sizing Solar Panel Systems

When sizing a solar panel system for your off-grid cabin, consider the total daily kWh needs, the peak hours of energy usage, and the storage capacity. A general rule of thumb is to size the solar panel system to produce 1.3-1.5 times the total daily kWh needs to account for cloud cover, system inefficiencies, and energy storage. For example, if the daily kWh needs are 0.286 kWh, you would need to size the solar panel system to produce 0.373-0.43 kWh (1.3-1.5 x 0.286 kWh) per day.