Quick Answer
Solar panels need at least 5-6 peak sun hours (PSH) of sunlight daily to function efficiently and meet their rated capacity. This translates to approximately 4-5 hours of direct sunlight with an average power density of 200-240 watts per square meter. However, the actual energy output may vary depending on factors such as panel efficiency, temperature, and shading.
Understanding Peak Sun Hours (PSH)
Peak sun hours (PSH) are a measure of the amount of sunlight a location receives during a specific period. In the Northern Hemisphere, the southern side of a structure typically receives more PSH than the northern side. For off-grid solar systems, a minimum of 5-6 PSH is recommended to ensure reliable energy production. For example, a location with 5 PSH can produce around 20-25 kWh of electricity per day for a 4 kW solar array.
Load Calculation and Solar System Sizing
To determine the required solar panel size, you need to calculate the total daily load in watt-hours (Wh). This involves identifying all electrical devices and appliances, calculating their power consumption in watts (W), and multiplying it by the number of operating hours per day. For instance, a refrigerator consumes 100 W and operates for 8 hours a day, resulting in a daily load of 800 Wh. By summing up the daily loads of all appliances, you can determine the total system size needed to meet the load requirements.
Panel Battery Inverter Sizing Worksheet
When sizing a solar panel system, it’s essential to consider the battery bank size and inverter capacity. A worksheet can help simplify this process. Start by calculating the daily load in watt-hours (Wh) and the recommended battery bank size in amp-hours (Ah). Then, determine the inverter capacity based on the panel size, battery bank size, and desired depth of discharge (DOD). For example, a 12,000 Wh daily load may require a 4,000 Ah battery bank and a 4,000 W inverter.
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