What Size Energy Storage System Do I Need to Go Completely Off-Grid?

In recent years, there has been a notable growth of interest in off-grid living. This lifestyle transition is driven by a desire for self-sufficiency, environmental sustainability, and resiliency against fluctuating energy costs and grid instabilities. Advancements in renewable energy technologies, particularly solar plus storage solutions, have made off-grid living more accessible.

To ensure a reliable energy supply for complete off-grid living, homeowners need to accurately determine the size of the required energy storage system. Undersized systems may not adequately handle simultaneous appliance usage or peak power demands, while oversized systems can result in unnecessary expenses. Therefore, careful planning and accurate calculations are imperative to balance cost and reliability in your journey toward full energy autonomy.

The Estimation of Off-Grid Household Energy Demand

To design an effective off-grid energy system, it is critical to accurately estimate your household's energy demands. This involves understanding both the continuous power requirements during peak times and the total daily energy consumption.

Continuous Power Requirements During Peak Times

Note: Power ratings are approximate and can vary based on the model

Peak Power Demand Estimations:

Morning Peak:

• Coffee Maker: 800 W
• Toaster: 800 W
• Microwave Oven: 1,000 W
• Hair Dryer: 1,500 W
• Indoor Lighting: 300 W 
• Wifi Router: 10 W
• Refrigerator: 150 W 

Total Estimated Morning Peak Demand: 4,560 W

Evening Peak:

• Electric Oven: 2,000 W
• Refrigerator: 150 W
• Television: 100 W
• Computer: 150 W
• HVAC System: 3,500 W
• Wifi Router: 10 W
• Dishwasher: 1,200 W

Total Estimated Evening Peak Demand: 7,110 W

In this scenario, the evening peak demand is higher, suggesting your system should handle around 7 kW during peak times.

Total Daily Energy Consumption: 

As of 2024, the average American home consumes 30-33 kWh of electricity per day. For a solar plus battery system, a common recommendation for the battery storage capacity is to cover approximately 70% of a household's daily energy consumption in off-grid situations. This means the battery capacity should be around 21 to 23 kWh to ensure a sufficient power supply 24/7. However, given the fact that there are overcast or stormy days, it’s advisable to have an energy storage system capable of covering 100% of daily energy consumption, meaning a 30-33 kWh is the ideal battery capacity. 

This full coverage approach provides greater reliability, allowing the home to function normally without immediate solar input.

Factors Influencing Your Energy Demand for an Off-Grid Lifestyle

The following factors can cause your energy demand to differ from that of a typical household. Homeowners can size their energy storage systems more accurately by accounting for these factors.

Geographical Considerations: Weather and Climate

Where you live plays a big role in determining how much energy you’ll need. For example, households in colder climates may rely much more heavily on electric heating, while those in warmer regions face significantly greater demand for air conditioning. 

Property Size and Energy Habits

Larger homes naturally have higher energy demands—more lighting, more rooms to heat or cool, and potentially more appliances. A household with advanced energy use patterns, such as electric vehicles, home offices, or smart home automation, will also see greater power consumption.

Behavior matters too. Families who cook frequently with electric appliances or run multiple high-consumption devices at once will need more robust energy storage than more energy-conscious households.

How Many Home Batteries Do I Need to Be 100% Off-Grid?

Taking FranklinWH aPower 2 as an example, which stands apart with 10 kW continuous power and 15 kWh of storage capacity per unit, you may only need two aPower 2 units to be off-gird 24/7 if you have the energy consumption pattern of a typical household. 

Advantages of the FranklinWH System in Empowering 100% Off-Grid Living

Large Solar Input

The FranklinWH System is designed to accommodate high solar input, which enables reliable off-grid living. The aGate, FranklinWH’s intelligent system controller, features two independent solar input interfaces, each capable of handling up to 63 amps. It allows homeowners to connect larger or multiple solar arrays, maximizing daytime energy capture—especially important during winter or in places with shorter sunlight hours. 

Multi-Source Orchestration

Off-grid living demands high energy reliability and security, and FranklinWH rises to the challenge with powerful multi-source orchestration. In addition to solar and battery, the FranklinWH System supports generator integration and Vehicle-to-Load (V2L) functionality, enabling it to intelligently pull energy from multiple sources.

Reliable Black Start

When the batteries are drained due to low PV production, unintentional overuse or unforeseen high demands, which shuts down your whole system, black start will be triggered to restart your system with a 99% success rate to restore electricity to your home. 

Built to Meet the Most Demanding Needs

The FranklinWH aPower 2 battery can support even the most power-hungry appliances in a modern home. Each unit delivers 10 kW continuous power and 15 kWh of storage capacity, and can handle the startup of the most demanding electrical home loads with an LRA of up to 185 A, such as a 5-ton A/C. Being future-proof, you can expand the capacity by adding more aPower batteries as your power needs grow.

Adaptive Load Control

When living off-grid, every watt counts, and the FranklinWH System makes sure it’s used wisely. With Smart Circuits, the system can intelligently switch between advanced and critical load backup via preset schedules or manual choice to ensure sufficient home power.

Conclusion

Achieving 100% off-grid living is no longer a distant goal. By meticulously assessing your household’s energy demand, you can accurately size an energy storage system that enables a reliable off-grid lifestyle. FranklinWH offers a robust solution that empowers 100% off-grid independence. If you're seeking sustainability and total energy freedom, look nowhere else.