What Type of Light Is Best for Solar Panels?

A solar panel is used to convert the energy of sunlight into electrical energy. As sunlight hits the solar panel, it is absorbed by a semi-conducting material. As it is absorbed, electrons, knocked away from their atoms, flow through the material to create electrical energy. If you have a collection of solar panels, you will be able to change sunlight’s energy into enough direct current (DC) electricity to power light bulbs.

The question then is this: what type of light is best for solar panels? In choosing a light bulb, should you choose incandescent, halogen, or fluorescent to get the greatest amount of light from your solar panel?

Typical Light Usage

A typical family has 30 light bulbs in their home. Those bulbs use about $200 worth of commercially produced electricity each year. When you use solar panels, you want to couple them to the most energy-efficient lighting. Consider the three types of light currently available.

1. Incandescent: Incandescent is the poorest type of light for solar panels. Incandescent bulbs convert as much as 95% of the energy they receive to heat rather than light. If solar panels light such bulbs, only about ~5% of the power generated by the solar panels is producing visible light. This is very inefficient compared to newer bulbs - so inefficient, in fact, that in February 2007, Australia banned the use of incandescent bulbs by 2010. Other countries are debating similar measures.

When considering what type of light is best for solar panels, we must rule out standard incandescent light. In order to power just the 30 of these inefficient bulbs found in an average home, you would need as many as 30 square yards of solar panels.

2. Halogen: Halogen lights produce very bright light from a small bulb, and may seem a good choice for solar panel usage. They are a type of incandescent light, but produce about 9% efficiency instead of the ~5% of a standard incandescent bulb. A “best quality” halogen bulb of 60 watts produces the same amount of light as a 100 watt regular incandescent bulb. They can be dangerous, however, and are still not the best choice for solar panels.

3. Fluorescent: The best light for use with a solar panel is the fluorescent bulb. These light bulbs are long-lasting, and very efficient - about 20% of your energy will be converted into light. A compact fluorescent lamp (CFL) fits a standard light socket, and uses far less electricity than other types. One CFL may produce as much light as 4 standard bulbs.

CFLs can be purchased for DC input directly from a solar panel, and are used just that way in many developing countries.

In some isolated locations, CFLs are used in streetlights powered by solar panels.

Fluorescent lighting is not perfect, but it is the best of the three for use with a solar panel.