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How many watts of power hit a solar panel from the sun, and how long does it take for the solar panel to charge a battery? (Use any solar panel and battery rating.)

Answer :

Final answer:

A solar panel's power output depends on factors like efficiency and sunlight intensity; under ideal conditions, a panel's expected power can be calculated, but derating due to real-world conditions must be considered. To calculate how long it takes to charge a battery, divide the battery's capacity by the solar panel's average power output, adjusted for efficiency losses.

Explanation:

When it comes to determining the power that hits a solar panel from the sun, various factors should be taken into account, such as the panel's efficiency, its size, and the intensity of sunlight it receives. For instance, a typical solar panel is rated in terms of peak watts, which measures what the panel would produce under ideal conditions of 1,000 W/m² sunlight. Assuming a solar panel is 18% efficient and measures 0.8 m by 1.5 m, it would deliver:

  • Area = 0.8 m * 1.5 m = 1.2 m²
  • Power received = 1,000 W/m² * 1.2 m² = 1,200 W
  • Efficiency = 18%
  • Expected power output = 1,200 W * 0.18 = 216 W under full sun

However, due to real-world conditions such as temperature and suboptimal angles of incidence, the power output is often derated by about 85-90%, leading to an average power output closer to 45 W for a 250 W panel during 4.8 full-sun-equivalent hours.

To calculate how long it would take to charge a battery, you first need the battery's capacity in watt-hours (Wh) and then divide it by the average power output of the solar panel. The actual charging time will also be influenced by the efficiency of the charge controller and the battery's state of charge. Without specific battery capacity and the aforementioned efficiencies, it's not possible to provide an exact charging time.