The primary factor determining your off-grid system size is your Daily Energy Consumption, measured in Watt-hours (Wh) or kilowatt-hours (kWh). Below is a combination of multiple calculators that consider these variables and allow you to. . In California and Texas, where we have the most solar panels installed, we get 5. 92 peak sun hours per day, respectively. For 10kW per day, you would need about a 3kW solar system. Here's a practical example: Imagine you have a 100-watt lightbulb turned on for 10 hours. What Can a 3kw Solar System Run? A 3kW solar system is a popular. . For the average shed, it would need around 2. . Most homeowners need between 15-25 solar panels to power their entire home, but this number varies significantly based on your energy usage, location, and roof characteristics.