Watts and Lumens

In the days of incandescent light bulbs, you could determine the bulb's brightness by the number of watts printed on the package.

What's a watt?

When buying an incandescent light bulb, the watts rating gives consumers a good indication of how bright a bulb is. The more watts, the brighter the bulb. However, Watts are not a measure a brightness, they’re a measure of energy consumption – that is, how much electricity a bulb uses. With today's LED bulbs, brightness is measured in lumens. 

That rule doesn't apply to LED bulbs. An LED that uses 60 watts is in no way comparable to an incandescent bulb that uses 60 watts. LEDs are designed to use less energy and naturally have a lower watt rating. This means it's useless to use watts to determine brightness.

To fix the problem, bulb companies have started using lumens to rate bulbs. This gives you a more accurate indication of how much light to expect from an LED.

Why lumens?

The easiest way to figure out what bulb you need is by using an incandescent/LED conversion cart.

Say you normally use a 60-watt incandescent bulb, for example. You would probably want to choose an LED bulb that uses 10 to 15 watts and has a lumen rating of 900 to get the same illumination. This conversion chart will help you find an LED bulb similar to the incandescent you've been using:

 Lumens to watts table:


light bulb watts

Fluorescent/ LED watts


375 lm

25 W

6 W

600 lm

40 W

8-10 W

900 lm

60 W

10-15 W

1125 lm

75 W

12-18 W

1500 lm

100 W

15-23 W

2250 lm

150 W

37 W

3000 lm

200 W

50 W


What does the IP rating mean?

IP is the name of the standard that was drawn up by the International Electrotechnical Commission (IEC) to determine how resistant an electrical device is to fresh water and common raw materials – like dirt, dust and sand.

The first two letters “IP” indicates that it is an IP code
– The first digit represents the level of protection against solid particles such as dust
– The second digit describes the level of protection against liquids such as water

IPX4 Rating

Weatherproof means the light has been tested to resist splashing water on all sides. The test duration is five minutes, with 10 litres of water splashing the light per minute. An IPX4 designated flashlight will be protected against moisture, condensation, and exposure to the elements such as rain.

IP67 rating means the unit can be dropped into a body of water up to a meter deep for half an hour,

IP68 rating guarantees protection in water up to 1.5m deep for the same period of time. Both are resistant to dust.


What is difference between Amp-hours(Ah) and Watt-hours(Wh)?
An Amp Hour (Ah) is a measure of charge (measured in "Coulombs") whereas a Watt Hour (Wh) is a measure of energy. The two are related by voltage. So a 36 V battery stores twice the energy (Wh) of an 18 V battery.
Generally, we use mAh for cells and batteries, whereas watt-hours for energy storage systems.


What is the difference between W (Watts) and Wh (Watts per hour) 

In a nutshell, watt-hours measure amounts of energy for a specific period of time, and watts measure rates of power at a moment in time. A common analogy for watts and watt-hours is speed and distance. ... Similarly, if a 60 W light bulb is on for one hour, then that light bulb will have used 60 Wh of energy.

How to Convert Watt-hours(Wh) to Amp-hours(Ah):

Divide the amount of watt-hours by the number of volts to convert:e.g. 180 Wh ÷ 12 V = 15 Ah. This is the equivalent of 15 amps of current running for one hour, or – as in this case – 5 amps of current for three hours.

Current in Amps = Power in Watts/Voltage

 Power in Watts = Current in Amps x Voltage

How to Convert amps hours(Ah) to watt-hours(Wh):

The formula is:

Wh = mAh × V / 1000

For example to convert 10,000 mAh to Wh for 3.6 battery capacity:

10000 x 3.6/1000 = 36 Wh.


Area covered by Watts (Approx):

10 W: 10 square meters

30 W: 20 square meters

50 W: 40 square meters

100 W: 80 square meters

200 W: 150 square meters

300 W: 200 square meters

400 W: 300 square meters



Where is the best place to display my outdoor solar lights?
Outdoor solar lights need direct sunlight to receive a full charge during the day. At night, the solar outdoor lights can be placed in the darkest area of the yard, away from any light source such as a street lights or outdoor wall lights.

How long will solar lights run?
The more sunlight the outdoor solar light receives during the day, the longer the run time at night. As most operating times may vary, the average outdoor solar light will stay illuminated for up to 15 hours.

What affects the outdoor solar lights' run time?
Usually outdoor solar lights will perform better during the summer months because the days are longer, which gives the light more electricity. Cloudy days and short winter days will reduce the amount of electricity the solar lights will receive, so the lights may not stay on as long.

What are the advantages of outdoor solar lighting?
Outdoor solar lights are very easy to install, usually with just a screwdriver. Since you don’t have to worry about where your power source is, you can set up outdoor solar lights just about anywhere there is ample light during the day and darkness at night. There is no wiring to hook up and no special lighting parts to purchase. Solar outdoor lights are also environmentally-friendly since they require no external power supply and they cost nothing to run.

Does the weather affect my outdoor solar lights?
Since the outdoor solar lights require direct sunlight to charge, cloudy days will inhibit the solar light from receiving a full charge. Most of the casings on outdoor solar lights are designed to be weather-resistant.

Can I use my outdoor solar lights in the winter?
If you live in a moderate winter climate that receives very little rain, such as California or Arizona, you can leave your outdoor solar lights out all-year long. However, if you live in an area that gets rain or snow, you should store your outdoor solar lights during these months. When storing the solar outdoor lights, make sure the on/off switch is in the off position and the solar lights are stored in a dark, dry location.

How do I charge my outdoor solar light’s battery?
The batteries on the outdoor solar lights charge via sunlight, so no special battery charger is required. Read the instructions that come with your outdoor solar light to see how to charge the battery upon initial set up (usually the outdoor solar light will need to be set up outdoors and left in the off position for 3 days before use).

How do I install outdoor solar lights?
It takes just a couple of minutes to install outdoor solar lights. Since solar outdoor lights require no wiring, no power source and no digging, installing them is as easy as removing them from the packaging, setting up the solar panel and placing the solar light where you want it. Generally, the only tool that is needed to install outdoor solar lights is a screwdriver.

Why is there an on/off switch on my outdoor solar lights?
Outdoor solar lights come with an on/off switch so you can control when you want your solar light to turn on. If you want the outdoor solar light to continue to work all day every day, you can simply leave the on/off switch in the on position. If you want to charge the outdoor solar light and use the light at a later time (such as a weekend party), you can turn the on/off switch to off until you are ready to use it. When the switch is in the off position, the light will continue to receive electricity from the sun and store it for later use.

My outdoor solar light was charged all day, but doesn’t come on at night. What is wrong?
First, check to make sure the on/off switch is in the on position. To turn the light on just press the button for two second to ignite the light. Second, make sure another light source isn’t preventing the light from turning it on. Move your outdoor solar light to a darker location and see if the light comes on. If it still doesn’t illuminate, check to make sure the batteries are fully charged. Move the solar panel to another spot during the day to see if it will receive more sunlight. Note: The batteries included with your solar charging panel will need to be replaced when their charging ability is decreased. They should be replaced approximately every two years.

How long do solar lights last?

Generally speaking, the batteries in outdoor solar lights expected to last about 4-5 years before they will need to be replaced. The LEDs themselves can last ten years or more.

You will know that it is time to change parts when the lights are unable to maintain charge to illuminate the area during the night.

To enhance your outdoor solar lights longevity, make sure that are placed in direct sunlight at a distance from street lighting or house lighting, as too close of a proximity can damage the sensors that cause them to kick on in low lighting.

The cleanliness of the solar panels also affects solar light longevity. Especially if you have your lights located near a dirty area, be sure to wipe off the panels every other week so that they get sufficient sunlight.

While most lighting systems are designed to withstand various kinds of weather and climates, they function best when they can receive a full day of direct sunlight and are not at risk of being covered in snow or knocked over by severe winds. If you are concerned about the weather at particular times of year affecting your solar lights, consider storing them for these periods.  

What is a solar charge controller?

charge controller or charge regulator is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery.


Connection of Solar Panel, Battery and Solar Charge Controller

Connection and disconnection order

Connection order:
  • First step: Connect the battery to the solar charge controller.
  • Second step: Connect the solar panel to the controller.
  • The last step: Connect the load to the controller.
Disconnection order:
  • First step: Disconnect the load with solar charge controller.
  • Second step: Disconnect the controller with solar panel.
  • the last step: Disconnect the battery with the solar charge controller.


Cleaning Panels

Use warm water and a soft sponge or cloth to clean your panel and keep the controller dry

Will hail hurt my solar panel?

All glass used in solar panels is toughened & factory tested to international standards. A small amount of hail is not a problem.

Do the solar panel systems make any noise?

No, they do not make noise.

Will dirty glass on my solar panel reduce the power it creates?

Yes, please keep the glass area of your solar panel as clean as possible. All dirty marks or films on the glass surface will reduce the efficiency. Keep it free from bird and bat droppings as they may permanently mark the glass surface. Clean with a moist soft cloth.

What can I run with a solar panel?

The solar panel will charge a battery while it’s in the sun. This type of unit is commonly used to run lights, DC fans and small DC devices.