At the initial design stage, solar street lights will calculate the required capacity of photovoltaic panels and batteries based on the customer's lighting time needs. Generally, a lighting period of 6 hours, 8 hours, and 12 hours is sufficient to meet the lighting needs.

However, when the battery leaves the factory, due to various factors considered during transportation, its power is not full. When configuring solar street lights, we also need to consider maintaining the battery's power during initial use. We need to calculate the discharge capacity of the day before yesterday and the number of rainy and cloudy days in the future (because sometimes continuous rainy and cloudy days may occur).

Ensure that the battery of solar street lights does not suffer losses during long-term cyclic discharge. Generally, when calculating the battery capacity at the beginning, the number of rainy and cloudy days is considered to be 3 days. Adding the time from the day before yesterday, the total number of rainy and cloudy days is 4 days. Therefore, the battery capacity will increase, which will affect the cost increase. The calculated battery capacity can ensure the service life of the battery. It won't cause battery losses. I believe many users have been using solar street lights for less than two years, and the lights won't light up! This is because some businesses, at the beginning, calculate the number of negative days less in order to reduce cost, resulting in long-term insufficient charging of batteries and causing losses.