The popularity of solar lights has led to a dizzying array of options on the market. Here are the factors to consider when choosing an outdoor solar light.

1. Purpose
Find out how you plan to use your solar lights before shopping. Do you need it for specific functions like safety and security, or are you looking for a decorative unit? Each use results in different design choices and features.

2. Desired brightness
Brightness is now measured in lumens. Lumens are more useful than the old wattage measurement. Old-fashioned 40-watt incandescent bulbs are between 300 and 500 lumens. An LED light with the same number of lumens consumes only 3 to 5 watts.

3. Types of solar panels
The three most common types of solar panels used to power solar lamps are amorphous, polycrystalline, and monocrystalline.

Amorphous has a photovoltaic layer over the entire surface of the cell. They are thin, flexible and lightweight.

Monocrystalline solar panels consist of a single silicon solar cell. They are sturdy and bulky, but are the best at generating electricity efficiently.

Polycrystalline solar panels are made of several silicon crystal sheets fused together. Like the single crystal varieties, they are heavy and hard. They are budget friendly.

4. Battery Type
You need your solar lights to work at night when there is no sun. That's where batteries come in. Batteries store electrical energy as chemical energy in reactions that occur when energy is stored and released.

Lead-acid batteries work when sulfuric acid reacts with lead. Other battery types include nickel-cadmium or nickel-cadmium batteries and nickel-metal hydride batteries, where the cadmium is replaced by a metal hydride. Each has performance differences in charging time, energy storage, weight and length of life.

5. Charging time and running time
Be sure to know how long each model takes to charge and how long they will run between charges. You may need a battery that lasts an entire night or more. Running a battery to zero repeatedly can drastically shorten its lifespan.

6. Bulb Type
Most energy efficient outdoor lighting uses LED technology. They are far more energy efficient than incandescent bulbs, and if broken like CFL bulbs, they don't risk releasing toxins into the environment. They are also more durable. 

7. Features and Accessories
The features and accessories you need are an important part of how to choose a solar light. You have manual and automatic options, and some are smart devices for your garden. Other types change color and intensity.