A. Your solar light vendors may be compromising on quality while saving some money.
B. Maybe the solar power products you have bought are made by some unauthentic manufacturer.
C. There are chances that the components (led chip, battery, controller, etc.), installed in the solar light you have bought, are not brand new.
D. Online sellers tend to sell quality products in order to get positive reviews, but when they get enough reviews, they start saving money while compromising on quality.
E. Online retailers sell many low quality solar products because the market demands it.
F. Remember that the price of the solar light varies based on the brightness a solar light can produce. Brightness is measured in lumens. The higher the lumens, the brighter the light and the higher the price.