Quick Answer
Assessing site suitability for off-grid solar installation involves evaluating factors such as solar irradiance, shading, roof orientation, and battery backup requirements.
Site Analysis
Conduct a site analysis to determine the solar irradiance and potential shading issues. Measure the solar irradiance at the site using a solar irradiance meter or by consulting online solar radiation data. For example, a site in Hawaii receives an average of 4.75 kWh/m²/day of solar irradiance, while a site in Arizona receives an average of 6.5 kWh/m²/day.
Roof and Site Assessment
Assess the site’s roof and surrounding area for potential shading issues. Consider factors such as nearby trees, buildings, and power lines that may block sunlight. Use a solar panel calculator or consult with a solar professional to determine the optimal roof orientation and tilt for the site. A south-facing roof with a tilt of 30° to 40° is generally ideal for off-grid solar installations.
Load Calculation and Sizing
Calculate the site’s energy load requirements using a load calculation worksheet or by consulting with a solar professional. Use data such as appliance wattages, lighting requirements, and water heater demands to determine the total energy load. For example, a typical off-grid home may require 2-4 kW of energy per day. Use this data to size the solar panel array, battery bank, and inverter system. A general rule of thumb is to size the solar panel array to produce 25-50% more energy than the site’s energy load requirements to account for variability and inefficiencies.
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