How to calculate the power concumption of solar light?

May 05 2017By Wayne Tseng342

There are many types of solar light on market like solar street light, all in one solar led batten light, or solar flood light.It is same way to calculate the power. While most of clients do not know how to judge whether the battery is matching with the lighting power consumption or not, then only can rely on the answer from salesman of suppliers. What's more, there is many salesman who answer clients' answer too facilely just in order to sell their products to client asap which causes a lot of compliant finally.  

For example. for same power 30W solar led street light, why does some solar street light have battery 20AH, but why other all in one solar street light have 16AH? what makes the difference? which one suits your requests more?  Let's learn it today.

First quetions is:  

How can i know the power consumption of your solar led batten light?  or solar led flood light per night? 

 Let's take Helios all in two 30W solar led street light as example. So you will know how to decide it.

As the default setting, HELIOS 30W is working with 100% power for first 6 hours and 50% power for next 6 hours without sensor. Then theoretically the power consumption per night is :

30W*6H +30W*50%*6H = 270WH,

and we need to include the power consumption of system, it is about 5% around. so we can get the total consumption roughly is 270WH*(1+5%)=283.5WH.

That means only the power of battery capacity is more than 283.5WH, the light will work as the default setting, or the light will stop working earlier. How to choose and calculate the right battery capacity? Based on above calculation, the power consumption is 283.5WH, normally the system for 30W is 12V for the battery. So the battery capacity should be: 


As we know the D.O.D (Depth of Discharge) of lead acid battery is 60-70% , so if this all in two solar led street light is using lead acid battery, the capacity should be: 12V  40AH (24/0.6=40). If lithium battery with D.O.D 100%, the battery capacity should be 12V 24AH. Normally Auroras always put more capacity as backup in order to extend lifetime of battery.  So when the power is 30W, Auroras is using 36AH battery. In above example, if the lighting mode is 50% power for 12 hours with sensor function, the power consumption will be much less.  As long as we know how to calculate it, we will know whether the specification is reasonable or not. So we need to choose the right battery capacity based on light consumption. No need to rely on supplier's description. 

Please share this article if it is helpful to you.


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