Solar Power…with Glasses?
Can a Magnifier Lens Amplify the Sun's Power?
Solar electric, or photovoltaic, power is on its way to becoming a viable technology for power generation. The problem with photovoltaic power is that the efficiency of solar cells is not very high, currently only up to 25%. The efficiency percentage is measured in a number of various ways, generally a ratio of the maximum potential power to the surface area of the cell multiplied by the irradiance of the light source. I intend to test whether using a Fresnel-type magnifying lens will concentrate more light, even at low incidence angles, to increase the electricity generated.
With the rising costs of energy, many people are looking for alternative ways of saving money by going “green”. One “green” solution includes solar panels but it is reported that they work best when exposed to full sun. My question: is it possible to maximize the efficiency of solar panels by placing a magnifier over them to concentrate more light when not fully exposed to the sun?
If I put a magnifier lens over the solar panel, then the light should be concentrated and will cause the voltage from the panel to increase.
· Solar cells work better when the energy is concentrated onto the solar panel's surface using special lenses, mirrors, and mirrored dishes to concentrate sunlight onto a solar panel. This means that smaller solar panels could be used to get more power. One of the disadvantages of using lenses or mirrors, however, means that the sun has to be tracked more closely than it would if the solar panel was used by itself.
· Photovoltaic Panels are used to transform sunlight energy into electrical energy. Photovoltaic means "light-electricity".
· Angle of incidence is a measure of deviation of something from "straight on". When the sun is at a low angle of incidence to the solar panel, the thought is that the lens would help concentrate light on the solar panel.
· Just as a magnifying lens concentrates the light onto a leaf causing the leaf to eventually burn, our experiment is to determine if the same concentrated light will actually increase the amount of voltage from the solar panel.
1. Solar cells or panels, 5W or less
2. A couple different types of magnifying lenses or light concentrators
3. Voltage meter for measuring generated power
4. Protractor for measuring angle of light source
1. Using a plain solar cell and voltage meter, determine the lowest angle of incidence where measurable voltage occurs
2. Using other materials (Fresnel lenses, magnifying lenses, clear bubble wrap, etc.) over the surface of the cell, measure their lowest angles of incidence.
I will measure solar cell angles of incidence without, and with, magnifying and light gathering materials. I will observe the effect certain magnifying or light gathering materials have on the ability to generate solar power. By using an artificial light source, the irradiance of the “sun” becomes a controlled variable, in that it will not change. The angle of the panel to the light, which I can control, is my independent variable. The generated voltage from the panel is my dependent variable, measured with a digital voltmeter.
The table shows angles in ten-degree increments, and the voltages with and without the magnifier lens placed over the solar panel. Instead of seeing higher voltages with the lens in place, the voltages are lower or nearly the same. The only exception to this is at 0º, where it is possible that light passed under the lens instead of through it. The graph shows the voltage measurements with and without the lens, and the size of the voltage difference at each angle.
Voltage Measured with Solar Panel at Specific Angles
Using/Not Using a Magnifying Lens
DC Voltage with Lens
DC Voltage without Lens
My experiment seems to show that the Fresnel lens actually scattered the light, or prevented some of it from reaching the panel. The extreme high and low angles appeared to result in nearly identical voltages generated. It's probable that the lowest angles produced nearly the same power with and without the lens because some light was reaching the panel through the gap between the lens and the panel (which was about 1”). The 90º angle was disappointing, because at such an angle, it demonstrated clearly the lack of effect the lens had on the measured power output. It was in the middle of the angle range that I hoped to see better voltages, but they were worse. Therefore, the best power generation is made with a bare panel, set so that faces the sun as it passes overhead during the day.