Quick Answer
To calculate your home's energy needs for solar, determine your average monthly electricity consumption in kilowatt-hours (kWh), then factor in your desired level of energy independence, such as covering 70-80% of your usage.
Calculating Your Energy Needs
To start, gather your past 12 months of electricity bills. Add up the total energy consumed in kWh, then divide by 12 to get your average monthly energy usage. For example, if your bills show 12 months of 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, and 1350 kWh, your average would be 1025 kWh/month.
Understanding Your Energy Load Profile
Not all appliances and devices are used at the same time. Your energy load profile will help you identify periods of high usage, such as morning and evening when lights and appliances are on. Consider using a Kill A Watt meter or other energy monitoring device to track your energy usage in real-time and gain a deeper understanding of your energy load profile.
Designing Your Solar System
Using your calculated energy needs and load profile, you can now design your solar grid tie system. Aim to oversize your system by 10-20% to account for variations in energy production and consumption. For example, if you need 1025 kWh/month, consider a 1200-1300 kWh/month system to ensure you meet your energy needs even on cloudy days or during periods of high usage.
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