# How to calculate the size of parameters when buying solar lamps and lanterns

The giant pit in the solar lighting market is the false labeling of parameters. There is no industry standard, and consumers only know that the higher the power, the brighter, the better. To cater to the market, merchants put the product parameters on an outrageous scale. Even many salespeople are not clear about the actual parameters of the lamps and lanterns and only recommend the highest parameters to their customers when selling them. Here, as a practitioner with the simplest way to let you see the actual parameters of the lamps and lanterns at a glance, know these formulas will be able to buy solar lights and lanterns above less fooled.

Solar lamps and lanterns photovoltaic panels and batteries configuration of the calculation formula
First of all, look at how our manufacturers need to do a solar light is to configure.

For example, to do a 30W solar street light 10 hours a day need to match how much photovoltaic panels and how big the battery?

First, calculate the total power consumption of the lamps and lanterns.
Currently used in residential solar street lights use segmented lighting. Calculate 30W solar street light, the first 4 hours 100% output, after 6 hours 50% output, equivalent to an entire load state for 7 hours. Then the total daily power consumption of this light is: 30W*7=210W

Second, calculate the battery capacity requirements. Current I = power P / voltage U
The lithium iron battery on the market is 3.2V a unit, and the ternary lithium is 3.7V a unit. The other voltage is nothing more than a parallel connection. There is no difference in capacity here to our standard 3.7V ternary lithium battery pack calculation.
The actual battery capacity requirements are: 210W/3.7V = 56.7AH

Third, calculate the need for photovoltaic panels. Power P = current I * voltage U
Most of the photovoltaic panels currently used in residential lighting for 6V and 12V because we use the battery is 3.7V. Photovoltaic panels generally use 6V, so here to 6V to calculate. The average sunshine hour in China is 4.5 hours.
Photovoltaic panels need to produce electricity per hour: 56.7AH/4.5H = 12.6A
The power of the photovoltaic panel is: 12.6A*6V=75.6W
By calculation, the actual power of a 30W solar spotlight is 10 hours of segmented lighting per day, which requires 56.7A of 3.7V ternary lithium battery pack and 6V 75.6W of PV panel.