## How to calculate the battery capacity of solar panels

1. Determine the battery capacity according to the electricity consumption needs,
Time (hours) = battery voltage (V) * battery capacity (AH) * 80% * 70% / power (W). In the formula for calculating battery power time, 80% means that the battery can only use 80% of the power. After photovoltaic, the battery life is shortened by 80%, and the efficiency of the inverter is about 70%.
2. Solar panel design, the output voltage of solar energy for 12V battery charging is 18V. According to the calculation of 9 hours of sunshine per day, search the local annual sunshine days on the Internet to determine the charging current.
Charging current = battery capacity*80%*130%*150%/9,
3. When charging, the battery converts electrical energy into chemical energy with a conversion efficiency of about 50%.
4. When discharging, the battery can only discharge 80% of its power. Over-discharge will shorten the battery's life, and the battery's over-discharge will shorten its life by 80%.
5. The average efficiency of the charger is about 70%.